Keywords : XRD

Effect on Structural, Electrical and Temperature Sensing behavior of Neodymium Doped Bismuth Ferrite

A. K. Sahu; Priyambada Mallick; S. K. Satpathy; Banarji Behera

Advanced Materials Letters, 2021, Volume 12, Issue 7, Pages 1-7
DOI: 10.5185/amlett.2021.071648

Synthesis of polycrystalline samples of Bi1-xNdxFeO3 [x = 0.5, 0.6, 0.7 and 0.8] were demonstrated following solid-state reaction method at high temperature. The structural properties of the sample were confirmed through the X-ray diffraction technique. The dielectric study of the compounds was performed at different frequencies in the range of 100 Hz – 10 6 Hz for various temperatures. The non-Debye type of relaxation process confirmed from impedance analysis. The materials showed a negative temperature coefficient of resistance (NTCR) behavior at various temperatures and frequencies. AC conductivity of the materials with frequency at different temperatures satisfied the universal power law of Johnscher. Thermistor constant (β), sensitivity factor (α), and stability factor for all the samples were calculated and confirmed the characteristics of NTC thermistor.

Structural, Optical and dielectric properties of Sr doped LaVO4

Khalid Sultan; Rubiya Samad; Feroz A. Najar; Shohaib Abass; Saima Jahan; Mudasir Rashid Rather; M. Ikram

Advanced Materials Letters, 2021, Volume 12, Issue 6, Pages 1-6
DOI: 10.5185/amlett.2021.061640

Polycrystalline bulk samples of chemical composition La1-xSrxVO4 (x = 0.0, 0.1, 0.3, 0.5) were prepared by solid state reaction method. The Morphology and structure wascharacterised by Scanning Electronic microscopy and powder X-ray diffraction respectively. All the prepared material were single-phase and co-doped ions were successfully incorporated in LaVO4 lattice. The EDAX spectrum shows that the percentage composition of given elements in the proposed formula was in good agreement with the corresponding values determined experimentally. The Raman spectra of LaVO4 reflect the VO4 type structure that consists of four different V–O bands. The prominent Raman band at about 860 cm -1 can be assigned to the symmetric V–O stretching mode while the weak Raman band at 792 cm -1 is assigned to antisymmetric V–O stretching mode. With increase in Sr doping, optical band gap was found to decrease resulting in increase in conductivity. The dielectric constant as well as dielectric loss shows a relaxor type of behaviour for higher doping concentration which can be attributed to the chemical pressure induced in LaVO4 with the doping of Sr ions. The studies performed on ac conductivity identifies that the conduction mechanism follows the charge hopping between localised states and follow the small polaron conduction.

Synthesis and Characterization of Gold Nanoparticles from Lobelia Nicotianifolia Leaf Extract and its Biological Activities

M.B. Lava; Uday M. Muddapur; B. Nagaraj

Advanced Materials Letters, 2020, Volume 11, Issue 3, Pages 1-4
DOI: 10.5185/amlett.2020.031491

Biosynthesis of gold nanoparticles is one among the best and cheap economical viable process, which is environmental friendly. The purpose of this study is to synthesis the gold nanoparticles using Lobelia nicotianifolia leaf extract and to investigate its biological activities. The synthesized gold nanoparticles were characterized by UV-vis spectroscopy, TEM, SAED, FTIR and XRD, the nanoparticles produced at maximum absorbance 532 nm. The Characterization study proved that the size and shape of AuNPs were spherical in shape, with an average size of 80 nm. Synthesized AuNPs were evaluated for various in-vitro biological studies.

Preparation and Characterization of Nickel Ferrite Nanoparticles via Sol-gel Method

Savithri. M. Nampoothiri; Viji. C; E. M. Mohammed; Robin Francis

Advanced Materials Letters, 2020, Volume 11, Issue 2, Pages 28-31
DOI: 10.5185/amlett.2020.021473

Nickel ferrite (NiFe₂O₄) nanoparticles were synthesized using sol-gel method and the powdered samples were sintered at 100°C and 200°C. X-ray Diffraction (XRD) patterns were used to determine the structure of nickel ferrite nanoparticles. Obtained the lattice parameter from the XRD data and calculated the particle size using Debye- Sherrer formula. The details of the surface morphology of NiFe2O4 nanoparticles were studied by Scanning Electron Microscopic (SEM) analysis. The work aims at the investigation of the dielectric properties such as dielectric loss and permittivity of Nickel ferrite nanoparticles at various frequencies and temperatures. In addition, the ac conductivity of the nickel ferrite nanoparticles was studied.

Influence of Iron Doping on Structural and Optical Properties of Nickel Oxide Nanoparticles

Nashiruddin Ahammed; M. Mehedi Hassan

Advanced Materials Letters, 2019, Volume 10, Issue 10, Pages 746-751
DOI: 10.5185/amlett.2019.0004

In this article, auto combustion prepared Ni1-xFexO (0≤x≤0.10) nanoparticles (NPs) have been investigated for their structural, morphological and optical properties. X-ray diffraction (XRD) studies reveal that all Fe doped NiO samples crystallize in single phase without any impurity. The crystallite size monotonically decreases from 20 nm to 10 nm with increasing Fe substitution. Transmission Electron Microscope images represent that the synthesized NiO NPs with size around 28 nm. A red shift in UV-Vis spectra indicates that band gap can be tuned by Fe doping from 3.76 eV to 2.51 eV because of the upward shifting of t2g level.  The broad transmittance peak in Fourier transform infra-red spectra at 500 cm -1 is assigned to Ni–O stretching vibration mode. Differential scanning calorimetry curve revealed that the transition at 250 o C was exothermic because of structural relaxation. Copyright © VBRI Press.

Gamma irradiation synthesis and in vitro drug release studies of ZnO/PVA hydrogel nanocomposites

Swaroop Kumaraswamy; Gangadhar Babaladimath; Vishalakshi Badalamoole; Somashekarappa H Mallaiah

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 546-552
DOI: 10.5185/amlett.2017.6819

In the present work, the synthesis of ZnO/PVA hydrogel nanocomposites was carried out using the gamma irradiation technique. The ZnO nanoparticles were synthesized using co-precipitation method and dispersed in the PVA solution. To prepare the ZnO/PVA hydrogel nanocomposites, the mixture was exposed to gamma irradiation dose of 25 kGy. The formation of ZnO nanoparticles in PVA matrix was confirmed using the powder X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and the UV-Visible Spectrophotometer (UV). The surface morphology of the hydrogels was studied using the Field Emission Scanning Electron Microscopy (FESEM). The swelling ratio and equilibrium degree of swelling (% EDS) were evaluated and there was drastic reduction in swelling and % EDS with the addition of ZnO nanoparticles to the PVA mixture. The l-ascorbic acid was loaded to the hydrogels and the release data was monitored by the absorption wavelength at 252 nm using UV. The drug release data was fitted to zero order, first order, Higuchi’s model, and Korsmeyer-Peppas’s model for the detailed analysis. The results suggest that ascorbic acid release from the hydrogel matrix follows the non-Fickian mechanism. 

Synthesis of Cu doped ZnO nanorods for photosensitive UV detection application

S. N. Sarangi; V. Siva; B. K. Padhi; P. K. Sahoo

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 524-530
DOI: 10.5185/amlett.2017.7022

We report the fabrication and characterization of photosensitive heterostructure device using pure and Cu doped ZnO nanorods on n-Si substrate using a low cost hydrothermal technique. Special techniques like Rutherford backscattering spectroscopy and Proton Induced X-ray emission (PIXE) were used to confirm the doping of Cu in ZnO nanorods. The PIXE measurements confirm the absence of any foreign element in parts per million level, except pure Cu doping in ZnO. The compressive stress in (002) peak develops after Cu doping is indicating the successful substitution of Cu +2 ions into Zn +2 lattice sites. The I-V measurement of 5% Cu doped ZnO device shows five orders of magnitude increase in current flow compared to 1% Cu doping.  Under ultraviolet (UV) light exposure further enhancement of the photocurrent in the devices has been observed, which demonstrates the capability of Cu doped ZnO nanorods as a potential UV photodetector. 

Study Of A-site Divalent Doping On Multiferroic Properties Of BFO Nanoparticles Processed Via Combustion Method

Baljinder Kaur; Lakhbir Singh; V. Annapu Reddy; Dae-Yong Jeong; Navneet Dabra; Jasbir S. Hundal

Advanced Materials Letters, 2016, Volume 7, Issue 12, Pages 1015-1020
DOI: 10.5185/amlett.2016.6457

Pure and Sr?doped bismuth ferrite Bi1-xSrx FeO3 (x = 0, 0.1, 0.2, 0.3) nanoparticles have been synthesized using combustion method. X- Ray diffraction study of these compounds confirms the rhombohedral structure with R3c space group. BiFeO3 peaks were observed at 2θ = 22.46o, 31.80o, 32.11o, 39.519o, 45.79o, 51.35o, 56.98o and 57.16o having miller indices as (012), (104), (110), (202), (024), (116), (214) respectively. The traces of secondary phase also appear along with desired phase of Sr?doped bismuth ferrite Bi1-xSrxFeO3 samples. The scanning electron microscopy of fractured pellets of the samples reveals the decrease in grain size with increase of Sr doping in Bi1-xSrxFeO3. Magnetic studies were carried out at room temperature up to a field of 10 kOe. M-H hysteresis loops showed a significant increase in magnetization with Sr substitution in BiFeO3. Compared to weak magnetisation with magnetizing field (M-H) shown by BiFeO3 nanoparticles (Remnant magnetization, Mr ~ 0.4x10-3 emu/g and coercive field, Hc ~ 0.065 kOe respectively), a significant enhancement in M-H loop was observed in Bi1-xSrx FeO3 compounds. The value of Mr ~ 0.525 emu/g and Hc ~ 3.70 kOe have been found to be maximum for x = 0.30 in Bi1-xSrx FeO3 compounds. Leakage current studies showed decrease in leakage current density of doped samples to that of pure BiFeO3 and x = 0.10 gives minimum value of 4.78 x 10-6 A/cm2 at 350 V/cm. The ferroelectric nature was confirmed by observed P-E loops in all the samples.

Synthesis And Characterization Of Ge Nanocrystals Embedded In High-k Dielectric (HfO2) Matrix

V. Saikiran; N. Manikanthababu; N. Srinivasa Rao; S. V. S. Nageswara Rao; A. P. Pathak

Advanced Materials Letters, 2016, Volume 7, Issue 12, Pages 957-963
DOI: 10.5185/amlett.2016.6403

Trilayered HfO2/Ge/HfO2 thin films were grown on Si substrate by RF magnetron sputtering with HfO2 and Ge targets. The subsequent rapid thermal annealing (RTA) of these films at 700 & 800°C results in formation of Ge nanocrystals (NCs) in HfO2 matrix. X-ray diffraction (XRD) and micro-Raman spectroscopy measurements were performed to confirm the formation of Ge NCs in the annealed samples. XRD results indicate that the as-deposited samples show amorphous behaviour, whereas the annealed samples clearly confirm the crystallinity of the films. The average size of the Ge NCs was found to increase with an increase in annealing temperature. Raman scattering studies confirm that the annealed samples exhibit a shift in peak position corresponding to Ge-Ge optical phonon vibrations, which clearly indicates the formation of Ge NCs. Conversely, as-deposited samples were also irradiated with swift heavy ions of 150 MeV Au and 80 MeV Ni at a fluence of 3×10 13 ions/cm 2 to synthesize Ge NCs. The structural properties of pristine and irradiated samples have been studied by using X-ray diffraction, Raman spectroscopy to substantiate the growth of Ge NCs upon irradiation. The results obtained by RTA are compared with the irradiated ones.

Rice Husks As A Sustainable Source Of High Quality Nanostructured Silica For High Performance Li-ion battery Requital By Sol-gel Method – A Review

K. Kaviyarasu; M. Jayachandran; M. Maaza; E. Manikandan; J. Kennedy

Advanced Materials Letters, 2016, Volume 7, Issue 9, Pages 684-696
DOI: 10.5185/amlett.2016.6192

The electronics industry is heavily reliant on the use of silicon in devices ranging from solar panels to circuitry. This is of growing concern due to the environmental impact of sourcing and refining the material. Thus, a green source of silicon is of vital importance to meet the growing demand for silicon in the industry. Rice husk represents an abundant source of nano silica. Currently the husk is considered a waste product that is separated from the grain during the milling process. Several methods have been trailed to extract the nano silica from rice husk. This paper reviews these current methods and presents suggestions of innovative research directions for processing techniques. This work reveals that the structural nature of superfine silica from rice husk ash is independent of the purification method, but dependent on the incineration temperature used. The paper concludes by advocating the physic-chemical process for producing high purity reactive nanosilica from rice husk. This method has the advantage of having high volume production versatility and being environmentally friendly. However, control of the morphology, shape, size, crystalline structure and chemical composition of rice husk nanostructures remains a challenge in the development of 3D nanopores arrays controllable by synthesis methods. We hope this article can provide the reader with snapshots of the recent development and future challenges.

L-lysine Derived Nickel Nanoparticles For Reductive Degradation Of Organic Dyes

Abdul Rauf Khaskheli; Saba Naz; Razium Ali Soomro; Faruk Ozul; Abdalaziz Aljabour; Nazar Hussain Kalwar; Abdul Waheed Mahesar; Imren Hatay Patir; Mustafa Ersoz

Advanced Materials Letters, 2016, Volume 7, Issue 8, Pages 616-621
DOI: 10.5185/amlett.2016.6215

This report demonstrates a facile and green fabrication method for the nickel nanoparticles using L-lysine as an efficient protecting agent. The application of green amino acid (L-lysine) enabled formation highly spherical and well-dispersed nanoparticles with average diameter in the range of 10 ±2.5 nm. UV-Vis spectroscopy was used as a primary tool to elaborately study and optimize the necessary experimental condition for the developed synthetic protocol. Fourier transform infrared spectroscopy (FTIR) was used to confirm the surface protection of Ni NPs via L-lysine molecules whereas; atomic force microscopy (AFM) and scanning electron microscopy (SEM) provided morphological and topographical view of the as-synthesized Ni NPs. In addition, small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) were used to evaluate compositional characteristics of fabricated L-lysine protected Ni NPs. The as-synthesized Ni NPs demonstrated excellent catalytic potential when utilized as heterogeneous catalyst for reduction of methylene Blue (MB) in the presence of sodium borohydride (NaBH4). The observed catalytic reaction was determined to follow pseudo first order kinetics with rate constant (K) and turn over frequency (TOF) determined to be 0.0224 and TOF value of 0.00411 s -1 respectively.

Structural, Morphological, Optical And Electrical Properties Of PbSe Thin Films Grown By Chemical Bath Deposition

Suresh Sagadevan; Jiban Podder;Isha Das

Advanced Materials Letters, 2016, Volume 7, Issue 5, Pages 410-413
DOI: 10.5185/amlett.2016.5949

Lead selenide (PbSe) thin films were processed by chemical bath deposition (CBD) technique. To analyze the structure and the crystallite size of PbSe thin film X-ray diffraction (XRD) analysis was used. Using Scanning Electron Microscopy (SEM) the surface examination of the film was conducted. With the help of UV-visible absorption spectrum investigation of the optical properties were held. All the optical constants were determined from UV-visible absorption spectrum. The dielectric examination of PbSe thin films were analyzed for various frequencies and various temperatures. The AC electrical conductivity analysis brought to light that the conduction depended on both the frequency and the temperature. Photoconductivity analysis was carried out to the PbSe thin films. 

Synthesis And Characterization Of Eu3+ Doped α-Al2O3 Nanocrystalline Powder For Novel Application in Latent Fingerprint Development

Amrita Das; Vishal Shama

Advanced Materials Letters, 2016, Volume 7, Issue 4, Pages 302-306
DOI: 10.5185/amlett.2016.6310

In the present study, we investigate upon the synthesis and characterization of inorganic Eu 3+ doped Al2O3 nanophosphor for its structural and luminescent properties. The luminescent nanopowder was prepared using a combustion method in which the stoichiometric ratio of oxidizers and fuel was fixed to one, with varying concentration of Eu 3+ ions acting as an activator. The prepared powder showed excellent thermal stability. For the identification of the phase and structure of the powder synthesized, X-ray diffractometer was used. From the XRD analysis, it is revealed that the rhombohedral crystallite phase of α-alumina was formed. The type of morphology and particle size was ascertained by Filed Emission-Scanning Electron Microscope (FE-SEM) and it was found that particles were having irregular spherical shape. A qualitative analysis of these nanophosphor particles was made using an Energy dispersive X-ray detector (EDS) and it was found that the samples were composed of Al, O and Eu ions. Photo-luminescence (PL) spectra were obtained using Spectrofluorometer absorption. The intense band position was observed at 618 nm and other less intense bands were also seen at 592 nm, 601 nm, 631 nm, while two weak bands were observed at 660 nm and 718 nm, when excited at 226 nm. The CIE color space chromaticity diagram was calculated from the CIE Calculator program using obtained PL spectra. The prepared nanophosphor powder was tested for latent fingerprint detection in forensic applications. The synthesized nanophosphor was successfully used as a latent fingerprint developing powder on various non-porous surfaces for forensic application. 

Electronic Structure Study And Dielectric Properties Of Amorphous ZrO2 And HfO2

Aditya Sharma; Shalendra Kumar;Hyun-Joon Shin; Mayora Varshney; Sejun Kang; Jaeyoon Baik; Tae-Kyun Ha; Keun-Hwa Chae

Advanced Materials Letters, 2016, Volume 7, Issue 1, Pages 17-22
DOI: 10.5185/amlett.2016.6136

ZrO2 and HfO2 powder samples were prepared by using the chemical precipitation method and subsequent annealing. Crystal structure, local electronic structure and dielectric constant of amorphous and crystalline powders of ZrO2 and HfO2 have been examined using the synchrotron X-ray diffraction, O K-edge X-ray absorption spectroscopy, Zr 3d and Hf 4f core-level X-ray photoelectron spectroscopy and temperature dependent dielectric measurements, respectively. Amorphous ZrO2 and HfO2 powders exhibit a local tetragonal structure, with mixed +3 and +4 valence states of Zr and Hf ions, and demonstrated the high dielectric performance. After the heat treatment, the tetragonal phase transforms into the monoclinic phase with dominant +4 valence state of Zr and Hf ions and the larger sized ZrO2 and HfO2 nanoparticles exhibited low dielectric constant. The manifestation of high dielectric constants in the amorphous ZrO2 and HfO2 samples is because of the hopping of electrons between the Zr +3 -Zr +4 and Hf +3 -Hf +4 networks. 

Gamma Radiation Assisted Biosynthesis Of Silver Nanoparticles And Their Characterization

R. Madhu Kumar; B. Lakshmeesha Rao; S. Asha; B. Narayana; K. Byrappa; Youjiang Wang; Donggang Yao; Y. Sangappa

Advanced Materials Letters, 2015, Volume 6, Issue 12, Pages 1088-1093
DOI: 10.5185/amlett.2015.6002

Silver nanoparticles (AgNPs) were synthesized in situ under gamma radiation environment at room temperature using aqueous silk fibroin (SF) solution obtained from Bombyx mori silk. The formation of the Ag NPs was confirmed by its characteristic surface plasmon resonance (SPR) band at around 424 nm in UV-visible spectra. The strength of the photoluminescence (PL) spectra decreases with increasing dosage reveals the optimum dose required for the synthesis of silver nanoparticles. Dynamic light scattering (DLS) measurement indicated the dose dependent size of the Ag NPs formed in the solution. The transmission electron microscopy (TEM) images showed that the formed nanoparticles are roughly spherical in shape. Further the X-ray diffraction (XRD) analysis confirms the nanocrystalline phase of silver with FCC crystal structure. From this study, it was found that the increasing the radiation dose increases the rate of reduction and decreases the particle size. The size of the Ag NPs can be tuned by controlling the radiation dose.

Single Oriented CeO2 Buffer Layer Deposition On Biaxially Textured Ni-W Substrate By RF Magnetron Sputtering

K.M.K. Srivatsa; Preetam Singh; Sourav Das

Advanced Materials Letters, 2015, Volume 6, Issue 10, Pages 883-887
DOI: 10.5185/amlett.2015.5884

Considerable attention has been gained on the deposition of CeO2 thin films with (200) single orientation as hetero-epitaxial buffer layer on (200) oriented biaxially textured flexible Ni substrates, in the fabrication of superconductor and semiconducting epitaxial thin films for device applications. In this work we have deposited (200) oriented CeO2 thin films on biaxially textured Ni-W substrate in a single-step process by RF magnetron sputtering, using CeO2 target. X-ray diffraction analysis shows that for the CeO2 thin film deposited at RF sputtering power below 200 W and for the substrate temperature of 700 o C, the film assumes single (200) orientation. For the substrate temperature below 700 o C and RF sputtering powers above 200 W the film shows polycrystalline nature with (111) and (200) orientations. The Raman spectrum of single oriented (200) CeO2 thin film shows only one sharp peak at about 464 cm -1 corresponds to the presence of F2g mode of CeO2. The ellipsometry studies reveal the value refractive index and optical band gap of single oriented film as 2.52 and 3.41 eV, respectively.

Structural, Dielectric, Magnetic And Magnetoelectric Characterization Of Co0.5Ni0.5Fe2O4 - Bi0.9La0.1FeO3 Composite

Manjusha and K. L. Yadav; Manjusha;K. L. Yadav

Advanced Materials Letters, 2015, Volume 6, Issue 10, Pages 853-861
DOI: 10.5185/amlett.2015.5856

Mixed spinel -perovskite composites of (x) Co0.5Ni0.5Fe2O4-(1−x) Bi0.9La0.1FeO3(x = 0, 0.25, 0.40, 0.55, 1.0) have been synthesized by conventional solid state reaction method and annealed at 850 ºC. The X-ray diffraction (XRD) pattern shows that the composites consisted of spinel Co0.5Ni0.5Fe2O4 and rhombohedral perovskite Bi0.9La0.1FeO3 ceramics. FESEM micrographs show closely packed microstructure with grain size in the range 503 nm - 960 nm. Variation of dielectric constant and dielectric loss with temperature at two fixed frequencies (500 kHz and 1 MHz) was studied. The composite with composition x = 0.55/sintered at 850 ºC exhibits the largest coercitivity (Hc) of 883 Oe. The saturation magnetization (Ms) and magnetic moment (µB) increase with an increase of Co0.5Ni0.5Fe2O4 concentration in the composites. From ferroelectric hysteresis loop analysis the values of remnant polarization (Pr) and coercive field (Ec) was found to lie in the range of 0.018-0.745 µC/cm 2 and 3.89-6.06 kV/cm. The relative change of magnetocapacitance was found to be 6.6% at a magnetic field of 8 kOe for x = 0.55 composition. Impedance analysis suggests the presence of a temperature dependent electrical relaxation in the material having a typical negative temperature coefficient of the resistance (NTCR) behavior analogous to a semiconductor.

Synthesis And Optical Characterization Of Ca2PO4Cl:Tb3+ And Mn2+ Phosphor For Solid State Lighting

N. S. Kokode; V. R. Panse; S. J. Dhoble

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 616-619
DOI: 10.5185/amlett.2015.SMS3

In present work we studied the luminescence properties of Tb 3+ and Mn 2+ doped Ca2PO4Cl phosphor synthesized by wet chemical method were studied with extra heat treatment, to understand the mechanism of excitation and the corresponding emission of prepared phosphor. For the green emission, Tb 3+ ion is used as an activator, the excitation and emission spectra indicate that this phosphor can be effectively excited by 380 nm, to exhibit bright green emission centered at 545 nm corresponding to the f→f transition of Tb 3+ ions. The emission spectrum of Mn 2+ ion at 405 nm excitation 4 T1(4G) -  6 A1(6S) gives an emission band at 591 nm (orange-red). The observed photoluminescence (PL) measurements of Tb 3+ and Mn 2+ activated prepared phosphor indicates that these are the outstanding green and orange-red emitting potential phosphor , suitable application for the solid state lighting. The synthesized phosphors were analyzed by X-ray diffraction (XRD) for confirmation of phase and purity. The morphology and structure were characterized by scanning electron microscopy. Thus the phosphors in this system may be chosen as the green component for the tri-color lamp and certainly applied in w-UV LEDs. In the view of the excitation band and excellent luminescent properties, Ca2PO4Cl:Tb 3+ and Mn 2+ phosphor is expected to be a potential candidate for application in n-UV white LEDs and solid-state lighting because of its cost-efficient manufacturing, mercury-free excitation and eco-friendly characteristics.

Study Of Chemically Synthesized SHI Irradiated CdS Nanostructured Films

P.K. Mochahari; Ananta Rajbongshi; Nava Choudhury; F. Singh; K.C. Sarma

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 354-358
DOI: 10.5185/amlett.2015.5719

Cadmium sulphide (CdS) nanostructured films were prepared by chemical bath deposition (CBD) method at room temperature. The prepared films were subjected to swift heavy ion (SHI) irradiation by using 100 MeV Si 8+ ion beams at various fluences from 1x10 11 to 1x10 13 ions/cm 2 . Structural, morphological, optical properties of the pristine and irradiated films were characterized by X-ray diffractrometer (XRD), high resolution transmission electron microscope (HRTEM), UV-Vis spectroscopy and Raman spectroscopy. XRD study confirms the formation of nanocrystalline cubic phase in all the films. The crystallite size is found to increase from 7nm to 9 nm and shift of peak positions are observed due to irradiation. The lattice strain and dislocation density of the samples are of the order of 10 -3 and 10 16 m -2 respectively and the values are found to decrease upon irradiation. HRTEM images show that the shapes of the particles are nearly spherical and the selected area electron diffraction (SAED) pattern of HRTEM have also supported the formation of cubic phase CdS. The optical absorption spectra exhibit shift in the fundamental absorption edge and the optical band gap decreases from 2.585eV to 2.513 upon SHI irradiation. Three intense Raman lines for pristine as well as irradiated CdS have been observed and all the samples show shift in Raman lines relative to bulk CdS due to phonon localization. The SHI irradiation on chemically deposited CdS films is an important tool used for modification of structural, morphological and optical properties of the films for possible applications in device fabrication.

SHI Induced Thermoluminescence Properties Of  sol-gel Derived Y2O3:Er3+ Nanophosphor

N.J. Shivaramu; B.N. Lakshminarasappa; K.R. Nagabhushana; Fouran Singh

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 342-347
DOI: 10.5185/amlett.2015.5713

Nanocrystalline erbium doped yttrium oxide (Y2O3:Er 3+ ) was synthesized by the sol-gel technique using citric acid as complexing agent. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) techniques for phase-purity and microstructure. Er 3+ doped Y2O3 crystallizes in cubic phase with an average crystallite size of 24.3 nm. The pellets of Y2O3:Er 3+ were irradiated with 100 MeV swift Si 8+ ions with fluence in the range of 3×10 11 - 3×10 13 ions cm -2 .  Three well resolved thermoluminescence (TL) glows with peaks at ~422, 525 and 620 K were observed in Er 3+ doped Y2O3 samples. It was observed that the TL intensity was found to increases with increasing Er 3+ concentration up to 0.4 mol% in Y2O3 and thereafter it decreases with further increase of Er 3+ concentration. Also, the intensity of low temperature TL glow peak (~422 K) increases with increasing ion fluence up to 1×10 12 ions cm -2 and decreases with further increase of ion fluences. The TL trap parameters were calculated by glow curve shape method and the deconvoluted glows were exhibit of second order kinetics.

Pomosynthesis And Biological Activity Of Silver Nanoparticles Using Passiflora Tripartita Fruit Extracts

Brajesh Kumar; Kumari Smita; Luis Cumbal; Alexis Debut; Javier Camacho; Elisabeth Hernández-Gallegos; María de Guadalupe Chávez-López; Marcelo Grijalva; Yolanda Angulo; Gustavo Rosero

Advanced Materials Letters, 2015, Volume 6, Issue 2, Pages 127-132
DOI: 10.5185/amlett.2015.5697

Silver nanoparticles (AgNPs) have been synthesized via the green pomosynthetic procedure, using Passiflora tripartita var. mollissima fruit pigments as both the reducing and stabilizing agents. UV–Vis Spectroscopy, Dynamic Light Scattering, Transmission Electron Microscopy with Selected Area Electron Diffraction and Powder X-Ray Diffraction are used to completely characterize the AgNPs. The prepared AgNPs are found to be mostly spherical shapes with an average diameter of 49.7 ± 24.6 nm at room temperature. XRD analysis revealed the face-centered cubic geometry of AgNPs whereas Infrared spectrum and cyclic voltammetry measurements hypothesize the possible biomolecules (flavonoid C & O-glycosides) responsible for stabilization of the AgNPs. Synthesized AgNPs shows significant antioxidant efficacy (67%, 0.15 mM) against 1, 1-diphenyl-2- picrylhydrazyl. The AgNPs (0.01 – 20 μΜ) did not affect cell proliferation of the human cancer cell lines A -549 and HeLa, from lung and cervix, respectively. The use of environmentally benign, cost-effective and renewable materials like P. tripartita extract offers numerous benefits of eco-friendliness and compatibility for potential future pharmaceutical and biomedical applications.

Impedance Spectroscopy And Conductivity Studies Of CdCl2 Doped Polymer Electrolyte

Mayank Pandey; Girish M. Joshi; Kalim Deshmukh; Jamil Ahmad

Advanced Materials Letters, 2015, Volume 6, Issue 2, Pages 165-171
DOI: 10.5185/amlett.2015.5639

Polyvinyl alcohol (PVA) and Polyvinyl Pyrrolidone (PVP) based polymer electrolytes for different loading wt% of CdCl2 were prepared by solution casting. The structural complexation was confirmed and interlayer spacing (d) was evaluated by using X-ray diffraction (XRD) study. The chemical bonding between polymer and salt was identified by using Fourier transform infrared spectroscopy (FTIR) technique. The FTIR peak at 3402.43 cm -1 in addition of PVP in PVA/CdCl2 composite demonstrates the grafting between two polymers. The presence of ionic bright channels and variation in morphology for different loading wt% of CdCl2 was confirmed by scanning electron microscope (SEM) and was also verified by Atomic force microscopy (AFM) micrographs. The analysis of impedance spectroscopy represented by semicircular pattern is driven by conduction mechanism and correlated with electrical conductivity. The enhanced AC conductivity of polymer electrolyte is directly proportional to frequency (50Hz-1MHz). The maximum value of DC conductivity 1.65x10 -5 S/m evaluated from Arrhenius plots and attribute to high mobility of free charges at higher temperature. The evaluated results of structural, morphological and electrical properties of present composites make the present research good for electrochemical devices.

Synthesis And Luminescent Performance Of LaPO4: Dy Nanophosphor

D. M. Pimpalshende; S. J. Dhoble

Advanced Materials Letters, 2014, Volume 5, Issue 12, Pages 688-691
DOI: 10.5185/amlett.2014.amwc472

Nowadays the research on synthesis of inorganic luminescent material with proper dimensions and morphologies has attracted great attention. Inorganic luminescent materials like LaPO4 have found many practical applications in the field of electroluminescent devices, integrated optics, biological labels, modern lighting and display fields. We have prepared Dysprosium (Dy) doped LaPO4 nanoparticles at relatively low temperature in polyethylene glycol (PEG) medium by wet chemical method. Dy 3+ is doped in LaPO4 at various atomic concentrations (1, 2, 5 and 10 at %). All the samples have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and thermoluminescence (TL) techniques. XRD study reveals the monoclinic structure of prepared nanoparticles. Unit cell volume is found to be decrease linearly with increasing Dy 3+ concentration indicating homogeneous substitution of La 3+ ions in LaPO4 by Dy 3+ . From the FTIR study it is found that the band at 1044 cm -1 assigned to the phosphate group PO4 3- in the region of υ3 anti-symmetric stretching of P-O band. The PL spectrum shows emission band at about 435 nm is observed due to the transision of Dy 3+ ions corresponding to wavelength in the blue color region. The glow curve of LaPO4: Dy phosphor obeys second order kinetics.

Photoluminescence Properties Of Eu3+, Ce3+ Doped LaPO4 Phosphors

Niyaz Parvin Shaik; N. V. Poornachandra Rao; K. V. R. Murthy

Advanced Materials Letters, 2014, Volume 5, Issue 12, Pages 722-727
DOI: 10.5185/amlett.2014.5572

Pure LaPO4 and LaPO4: Eu (0.5 mol %) Ce (0.5 mol %) phosphors were synthesized by the solid-state reaction method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra and the particle size analysis were used to characterize these samples. The XRD results reveal that the synthesized LaPO4:Eu (0.5 mol%) Ce (0.5 mol%) phosphors are well crystalline and assigned to the monoclinic structure with a main (120) diffraction peak. The calculated crystallite size of pure LaPO4 and LaPO4:Eu, Ce phosphors were 67.6nm and 64nm respectively. Upon excitation at 254nm wavelength, the emission spectrum of pure  LaPO4 phosphor emits a maximum intensity peak at 470 (blue) nm. In the emission spectrum of LaPO4:Eu 3+ Ce 3+ phosphor, the low contributions of the red (613nm) 5D0-7F2 emissions and the high intensity of the orange-red (589nm)5D0-7F1 emission results in high color purities.The most intense emissions appearing in the 580-620nm region is responsible for the strong orange-red luminescence observed in the Eu,Ce doped LaPO4 phosphor whose CIE colour coordinates are x = 0.57 and y = 0.43.Thus the prepared phosphors can be used as an orange-red emitting material in the field of illuminations and display devices.

Structural And Magnetic Properties Of Undoped And Mn Doped CdS Nanoparticles Prepared By Chemical Co-precipitation Method

Nikita H. Patel; M.P. Deshpande; Sandip V. Bhatt; Kamakshi R. Patel; S. H. Chaki

Advanced Materials Letters, 2014, Volume 5, Issue 11, Pages 671-677
DOI: 10.5185/amlett.2014.1574

Undoped and Mn doped CdS nanoparticles with varying Mn concentration of 10,15 and 20 mol % have been prepared by chemical co-precipitation method with polyvinylpyrrolidone (PVP) as capping agent at room temperature. EDAX has shown that no foreign impurities are present in the synthesized nanoparticles and X-ray diffraction (XRD) revealed that undoped and Mn doped CdS nanoparticles possess cubic phase with crystallite size ranging from 4-6 nm. Transmission electron microscopy (TEM) images indicated that nanoparticle sizes are between 2-6 nm and exhibits polycrystalline nature as seen from selected area electron diffraction (SAED) pattern. Raman spectra of undoped and Mn-doped CdS nanoparticles have shown 1LO and 2LO phonon modes and their intensity ratio decreases as Mn concentration increases. Magnetic susceptibility clearly pointed out that undoped CdS behaves as diamagnetic whereas Mn doped CdS as paramagnetic and varies nonlinearly with Mn concentration in CdS. Rapid increase in magnetization below 50 K temperature is observed in M-T curves which can be assigned to Mn ions isolated in CdS crystal field or extrinsic defects. The M-H curve at 5 K and 300 K for 20% Mn doped CdS nanoparticles at different magnetic fields showed no hystersis. In near future Mn doped CdS nanoparticles can be used for application in dilute magnetic semiconductor and fabrication of solar cells. The result and discussion drawn from this work are elaborated in detail in the paper.

Tb3+ Doped Sr2(BO3)Cl  Green Emitting Phosphor For Solid State Lighting

Vishal R. Panse; N.S. Kokode; S.J. Dhoble

Advanced Materials Letters, 2014, Volume 5, Issue 10, Pages 604-610
DOI: 10.5185/amlett.2014.amwc432

In this paper we present luminescence results on Tb 3+ doped Sr2(BO3)Cl green phosphor. The vibrational properties of Sr2(BO3)Cl phosphor was studied by Fourier transform infrared spectroscopy. Photoluminescence studies have been carried out to understand the mechanism of excitation and the corresponding emission in the as prepared phosphor. As the Tb 3+ ion is commonly used as an activator for the green emission, the excitation and emission spectra indicate that this phosphor can be effectively excited by 380 nm, to exhibit bright green emission centered at 546 nm corresponding to the f→f transition of Tb3 +ions.

Interfacial Mixing In Te/Bi Thin Film System

T. Diana; D. C. Agarwal; P. K. Kulriya; S. K. Tripathi; H. Nandakumar Sarma

Advanced Materials Letters, 2014, Volume 5, Issue 4, Pages 223-228
DOI: 10.5185/amlett.2013.7510

100 MeV Ag ions have been used to study the swift heavy ion (SHI) induced modification in Te/Bi bilayer system. The samples were analysed using Rutherford backscattering spectroscopy (RBS), Atomic force microscopy (AFM) and X-ray diffractometer (XRD). The elemental depth study with RBS results show a strong mixing between the top Te layer and the underlying Bi layer on irradiation. Surface roughness as calculated by AFM is found to increase from 8 to 30 nm on irradiation for the fluence 3x10 13 ions/cm 2 .  XRD results confirm the formation of Bi-Te alloy phases on mixing and are expected to be formed due to the interfacial reaction taking place within the molten ion tracks. Ion beam mixing has the potential to induce the formation Bi-Te alloy thin films which are the promising candidate for thermoelectric applications near room temperature.

Dielectric And Electrical Properties Of ZnSb2O4 Ceramics 

Anita Mekap; Piyush R. Das; R. N. P. Choudhary

Advanced Materials Letters, 2014, Volume 5, Issue 3, Pages 152-156
DOI: 10.5185/amlett.2013.fdm.65

The polycrystalline sample of ZnSb2O4 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction (XRD) studies of powder sample of ZnSb2O4 showed the formation of single-phase compound at room temperature. The surface morphology of the pellet sample of ZnSb2O4 was recorded at room temperature using a scanning electron microscope (SEM). Detailed studies of dielectric properties (εr, tan δ) and impedance parameters of the material provide an insight into the electrical properties and understanding of types of relaxation process occurred in the material. Temperature variation of dc conductivity shows that this compound exhibits negative temperature coefficient of resistance (NTCR) and frequency dependence of ac conductivity suggests that the material obeys Jonscher’s universal power law.

Swift Heavy Ion Irradiation Induced Structural, Optical And Conformational Modifications In Conducting Polymer Nanostructures

A. Kumar;Somik Banerjee

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 433-437
DOI: 10.5185/amlett.2012.ib.109

Structural and conformational modifications in conducting polymer nanostructures viz., Polyaniline (PAni) nanofibers induced by swift heavy ion (SHI) irradiation have been investigated employing TEM, XRD, UV-Vis, FTIR and micro-Raman spectroscopy. Upon interaction with the highly energetic ions, PAni nanofibers are fragmented and get amorphized. The local range of order is found to decrease with a corresponding increase in the concentration of point defects and dislocations leading to the enhancement in strain. Vibrational spectra of the pristine and SHI irradiated PAni nanofibers studied using FTIR and micro-Raman (μR) spectroscopy indicate conformational changes in PAni nanofibers upon SHI irradiation. Loss of π-stacking due to the enhancement in the torsion angle between Cring-N-Cring upon irradiation is indicative of strong electrostatic interaction between the electron rich C-N site in the aromatic rings of PAni chains and the ion beam. The most significant variation in PAni nanofibers upon SHI irradiation is the transformation of para di-substituted benzene (benzenoid) structure of PAni into the quinone di-imine (quinoid) structures; a phenomenon that has been simultaneously observed in both the FTIR and Raman spectra. The presence of two main peaks representing the same structures in PAni nanofibers in both the Raman and IR spectra is because of the presence of delocalized sp2 phases and local disorder in PAni nanofibers, which gives rise to electrical and mechanical fluctuations that destroy the symmetry rules.

Microwave Synthesis And Characterization Of Nanocrystalline Mn-Zn Ferrites

Surender Kumar; Tukaram J. Shinde; Pramod N. Vasambekar

Advanced Materials Letters, 2013, Volume 4, Issue 5, Pages 373-377
DOI: 10.5185/amlett.2012.10429

Powder diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the spinel structure of nanocrystalline Ferrites with composition Mn1-xZnxFe2O4 (x = 0.2, 0.4, 0.6 and 0.8) prepared by oxalate coprecipitation technique and followed by microwave heating of precursors. Effect of composition on the lattice constant, x-ray density, crystallite size was studied. Crystallite size and x-ray density increases with increase in Zinc content. The face centered cubic spinel structure has undergone deviation from ideality. A correlation exists between splitting of infrared absorption bands and lowering of composition dependent crystalline symmetry. This preparation technique could be used for synthesis of materials which use microwave transparent precursors.

Effect of copper on composition, structural and optical properties of copper doped znte thin films

R. Amutha

Advanced Materials Letters, 2013, Volume 4, Issue 3, Pages 225-229
DOI: 10.5185/amlett.2012.7387

Ultrathin (250 Å) initial deposit of copper on glass substrates were used for the subsequent deposition of ZnTe films under a pressure of 10 -5 by thermal evaporation method. The decrease of atomic percentage of copper with increase of the ZnTe film thickness is confirmed by EDAX analysis. The phase change from hexagonal to cubic structure is observed by XRD analysis. The strain (), grain size (D) and dislocation density ( ) were calculated and results are discussed. The transmittance and the optical bandgap energy were found decreases when increases of ZnTe film thickness. The optical transition of these films is found to be direct allowed. 

Neodymia-silica Nanocomposites: Sythesis and Structural Properties

Saruchi Surbhi; Praveen Aghamkar; Sushil Kumar

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 78-81
DOI: 10.5185/amlett.2013.icnano.109

Nanomaterials and nanostructures have received steadily growing interests as a result of their peculiar and fascinating properties and applications. Neodymia-silica nanocomposites were prepared by sol-gel route followed by calcination. The samples were prepared with different concentration of dopant (Nd2O3) and calcined in a programmable furnace at 1000 °C for 5 h. The structural evolution of samples was investigated by employing techniques such as XRD, FTIR and TEM. X-ray diffraction patterns showed that the samples were nanocrystalline and the size of crystallites has been determined using Debye-Scherrer relation. The FTIR spectra confirmed the presence of functional groups of prepared material. The particle size of samples was also estimated through TEM analysis. It has been observed that crystallinity as well as particle size of the samples increases with increase in dopant concentration.

Preparation and Characterization of The Chromium Doped ZnTe Thin Films

Dinesh C. Sharma; Y. K. Vijay;Y. K. Sharma; Subodh Srivastava

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 68-70
DOI: 10.5185/amlett.2013.icnano.118

The chromium doped zinc telluride (ZnTe:Cr) as well as ZnTe thin films and their sandwich structures were prepared onto glass substrate by thermal evaporation method under the vacuum of 10-5 Torr. We have studied the structural, optical and electrical properties of thermally evaporated Cr-doped ZnTe thin films as a function of Cr concentration. XRD measurements show that Cr-doped ZnTe films possess the mix phase of cubical and hexagonal structure of ZnTe thin film. The optical energy band gap (Eg) calculated from the optical absorption spectra which was observed around 2.57 eV for undoped ZnTe, and reduced to 1.47 eV for the Cr-doped thin films. The result of I-V characteristics is also presented in this paper.

Gas Sensing and Dielectric Studies on Cobalt Doped Hydroxyapatite thick films

Megha P. Mahabole; Ravindra U. Mene;Rajendra S. Khairnar

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 46-52
DOI: 10.5185/amlett.2013.icnano.146

This present paper deals with the investigation on effective utilization of cobalt doped hydroxyapatite (Co-HAp) thick films for improvement in gas sensing and dielectric properties. Chemical precipitation route is used for synthesis of nanocrystalline hydroxyapatite (HAp) bioceramic and ion exchange process is carried out for the partial substitution of cobalt ions in HAp matrix. Hydroxyapatite thick films, prepared using screen printing technique, are used as samples for gas sensing and dielectric measurements. The structural identification of HAp thick films is carried out using X-ray diffraction and the presence of functional groups in pure and doped HAp is confirmed by means FTIR spectroscopy. The surface morphology of these films is visualized by means of SEM and AFM analysis. Detailed study on CO2 gas sensing performance of pure and Co-HAp thick films is carried out wherein operating temperature, response/recovery times and gas uptake capacity are determined. It is remarkable to note that Co-HAp film with 0.01M cobalt concentration shows maximum sensitivity to CO2 gas at relatively lower operating temperature of 135 o C in comparison with pure HAp as well as other concentrations of cobalt doped HAp films. The frequency dependent variation of dielectric constant (K) and dielectric loss (tan δ) of HAp thick films are also studied in the range of 10 Hz-1MHz at room temperature. The result shows that increase of cobalt concentration in HAp matrix leads to increase in dielectric constant. The study reveals clear influence of cobalt substitution on dielectric properties and gas sensing properties HAp matrix.

Rapid Green Synthesis Of Silver And Gold Nanoparticles Using Peels Of Punica Granatum 

Naheed Ahmad; Seema Sharma;Radheshyam Rai

Advanced Materials Letters, 2012, Volume 3, Issue 5, Pages 376-380
DOI: 10.5185/amlett.2012.5357

We present a simple and eco-friendly biosynthesis of silver nanoparticles using Pomegranate peel extract as the reducing agent. Peel extract of Pomegranate was challenged with silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solution for the production of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs), respectively. The reaction process was simple for the formation of highly stable silver and gold nanoparticles at room temperature by using the biowaste of the fruit. The morphology and crystalline phase of the NPs were determined from UV-Vis spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) spectra. TEM studies showed that the average particle size of silver nanoparticles were 5 ±1.5 nm whereas the gold nanoparticles were found to be 10 ±1.5 nm. An effort has been also been made to understand the possible involved mechanism for the biosynthesis of the NPs. Presumably biosynthetic products or reduced cofactors play an important role in the reduction of respective salts to nanoparticles.

Structural And Electrical Properties Of Ba3Sr2GdTi3V7O30 

B. B. Mohanty; M. P. K. Sahoo;R. N. P. Choudhary; P. S. Sahoo

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 305-308
DOI: 10.5185/amlett.2011.11317

The polycrystalline Ba3Sr2GdTi3V7O30 material of tungsten bronze structural family was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray diffraction analysis exhibits the formation of single-phase compound with orthorhombic crystal system. Surface micrograph recorded by scanning electron microscopic (SEM) technique has well defined but non-uniformly distributed grains throughout the surface of the pellet sample. Detailed studies of dielectric properties as a function of temperature (306-773 K) and frequencies (10 2 -10 6 Hz) suggest that the compound has frequency independent diffused dielectric anomaly at a temperature ~620 K which may be related to ferroelectric phase transition which is confirmed from polarization study. The frequency and temperature dependence of impedance property of the material were analyzed using a complex impedance spectroscopy. The Nyquist plots confirmed the presence of grain and grain boundary effect in the material.

Microwave Induced Synthesis And Characterization Of Semiconducting 2-thiophenecarboxaldehyde Metal Complexes

A. P. Mishra; A. Tiwari; Rajendra K. Jain

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 213-219
DOI: 10.5185/amlett.2011.9307

The coordination complexes of Co(II), Ni(II) and Cu(II) derived from 2-thiophenecarboxylidene-3-chloro-4-fluoroaniline (TCC) and 2-thiophenecarboxylidene-4-fluoroaniline (TCF) have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, ESR, thermal, magnetic susceptibility, electrical conductivity and XRD analysis. The complexes are coloured and stable in air. Analytical data revealed that all the complexes exhibited 1:2 (metal:ligand) ratio with the coordination 4 or 6. FAB-mass and thermal data show degradation pattern of the complexes. The thermal behavior of metal complexes shows that the hydrated complexes loses water molecules of hydration in the first step; followed by decomposition of ligand molecules in the subsequent steps. The crystal system, lattice parameter, unit cell volume and number of molecules in unit cell in the lattice of complexes have been determined by XRD analysis. XRD patterns indicate crystalline nature for the complexes. The solid state electrical conductivity of the metal complexes has also been measured. Solid state electrical conductivity studies reflect semiconducting nature of the complexes.

Sol-gel Processing and characterization Of nanometersized (Ba, Sr) TiO3 ceramics

Kavita Verma; Seema Sharma; Dhananjay K Sharma; Raju Kumar; Radheshyam Rai

Advanced Materials Letters, 2012, Volume 3, Issue 1, Pages 44-49
DOI: 10.5185/amlett.2011.5264

 Ba0.5Sr0.3TiO3 (BST 70/30) nanopowders have been prepared by the modified sol-gel method using barium acetate, strontium acetate and titanium isopropoxide as the precursor. The formation mechanism, phase evolution, and particle size have been investigated using TG/DTA, XRD, and SEM. The fine particles of the nano-powders calcined are homogeneous and well-dispersed and their narrow size distribution is about 15–25 nm. The as-formed gel was dried at 2000 C and then calcined in the temperature range 6500 C to 8500 C for crystallization. Phase evolution during calcination was studied using X-ray diffraction (XRD) technique which exhibited cubic crystal structure with perovskite phase. Sintering of the pellet was performed at 9500 C and the study on the dielectric relaxation and the ac electrical conductivity behavior of modified Barium titanate, Ba0.5Sr0.3TiO3 ferroelectric ceramic exhibit that these are thermally activated process.

Eu3+ and Dy3+ activated Sr2V2O7 phosphor for solid-state lighting

Roshani Singh; S.J. Dhoble

Advanced Materials Letters, 2011, Volume 2, Issue 5, Pages 341-344
DOI: 10.5185/amlett.2011.3071am2011

Eu 3+ and Dy 3+ doped strontium vanadium oxide (Sr2V2O7) phosphor has been successfully synthesized using solid state diffusion method and characterized by XRD as well as photoluminescence (PL) measurements. The PL emission of Eu 3+ ion was observed in Sr2V2O7 phosphor at 593 nm and 618 nm in orange and red region of the spectrum, which corresponds to 5 D0→ 7 F1,  5 D0→ 7 F2 transitions, at the excitation wavelength of 393 nm. The PL emission of Dy 3+ ion was observed in Sr2V2O7 phosphor at 484 nm and 575 nm in blue and yellow region of the spectrum, which corresponds to 4 F9/2→ 6 H15/2 and 4 F9/2 → 6 H13/2 transitions, at the excitation wavelength of 349 nm. The 300 – 400 nm is Hg free excitation, which is characteristic of solid state lighting. Hence, Sr2V2O7 :RE [RE = Eu 3+ and Dy 3+ ] phosphors may be efficient materials for solid state lighting.

Intermetallic Al2Cu orientation and deviation angle measured by the rotating directional test during directional solidification

K. Gao; S.M. Li; H.Z. Fu

Advanced Materials Letters, 2011, Volume 2, Issue 5, Pages 368-372
DOI: 10.5185/amlett.2011.5013am2011

The orientation and deviation angle of intermetallic Al2Cu phase in directionally solidified Al-40wt. %Cu hypereutectic alloy were investigated using a rotating orientation X-ray diffraction (RO-XRD) method. Experimental results show that preferred planes (110) and (310) of the Al2Cu phase occur at 10 μm/s and the growth directions of the two planes are not well aligned with the heat flux direction. The growth direction of the preferred plane (110) has a 7.24 º~11.43 º angle with the heat flux direction. For the direction of the plane (310), its deviation angle attains 2.68 º ~ 20.82 º. Besides, the measured data agree well with the previously reported results, indicating that the RO-XRD method is an effective method for measuring the orientation and deviation angle of the phase in polycrystalline materials.

Photoluminescence studies of trichloro-DPQ organic phosphor

S.B. Raut; S.J. Dhoble; R.G. Atram

Advanced Materials Letters, 2011, Volume 2, Issue 5, Pages 373-376
DOI: 10.5185/amlett.2011.3075am2011

A new blue emitting material containing quinoline is designed, synthesized and characterized. The material has been prepared by well-known reaction such as Friedlander condensation reaction at 140 °C. The blended thin films of Trichloro-DPQ with poly (methyl methacrylate) (PMMA) at different weight % concentrations such as 10, 5, 1 and 0.1 weight % have been prepared. The structural characterization has been done by FTIR spectra. The synthesized polymeric compound demonstrates emission in blue region at 460 nm in powder form. At different weight % concentrations, there is emission at 444 nm with varying intensity. The light emitting and optoelectronic property of polymeric compound may find application in electroluminescence, OLED and sensors.

Novel phosphors of ALaLiWO6:Dy3+ (A = Sr2+ And Ba2+) for white light applications

Parag Nimishe; S.J. Dhoble

Advanced Materials Letters, 2011, Volume 2, Issue 5, Pages 358-361
DOI: 10.5185/amlett.2011.3073am2011

In this paper we report the synthesis and luminescence of Dy 3+ activated tungstates of the type ALaLiWO6 (where A = alkaline earth metals Sr and Ba), prepared by solid state diffusion reaction method. These novel luminescent tungstate materials were characterized by X-ray diffraction, scanning electron microscope (SEM) and photoluminescence (PL) techniques. The Dy 3+ activated ALaLiWO6 (where A = Sr and Ba) phosphors are effectively excited around 350 nm which is mercury free excitation in near UV and give a broad emission band peaking around 470 nm(blue region) along with a sharp characteristic peak at 577 nm (yellow region). Thus, the Dy 3+ activated ALaLiWO6 phosphors may be used in white light applications.

One step synthesis and X-ray induced luminescence in RGB PDP phosphors

J.G. Mahakhode; S.J. Dhoble; S.V. Moharil

Advanced Materials Letters, 2011, Volume 2, Issue 5, Pages 331-335
DOI: 10.5185/amlett.2011.3074am2011

One step combustion synthesis of preparation of plasma display panel (PDP) phosphors for X-ray induced luminescence is reported. The prepared phosphors were characterized by XRD, PL and X-ray excited luminescence (XEL) techniques. Phosphors emitting three primary colors have been be prepared by using the combustion synthesis. These may be used for X-ray imaging phosphors.

Combustion synthesis of X3.5Mg0.5Si3O8Cl4 (X3.5 = Sr,Ba):Eu2+ blue emitting phosphors

N.S. Dhoble; V.B. Pawade; S.J. Dhoble

Advanced Materials Letters, 2011, Volume 2, Issue 5, Pages 327-330
DOI: 10.5185/amlett.2011.3070am2011

Eu 2+ luminescence in novel Sr3.5Mg0.5Si3O8Cl4 and Ba3.5Mg0.5Si3O8Cl4 phosphors is reported in this paper. These were synthesized by combustion method at 550 o C furnace temperature. The prepared phosphors shows PL emission spectra at 445 nm, due to 4f 6 5d 1 → 4f 7 transition of Eu 2+ ions by monitoring excitation at 358 nm for Sr and Ba host lattice. Phase purity was checked by using XRD-pattern. The prepared phosphors have potential applications for solid-state lighting purpose.

Photoluminescence and ultraviolet photoresponse in ZnO nanophorsphors prepared by thermal decomposition of zinc acetate

Sheo K. Mishra; Smriti Srivastava; Rajneesh K. Srivastava; A.C. Panday; S.G. Prakash

Advanced Materials Letters, 2011, Volume 2, Issue 4, Pages 298-302
DOI: 10.5185/amlett.indias.210

In the present work, simple, low-cost, and direct route is used for the UV- photodetection and photoluminescent zinc-oxide nanoparticles (NPs) by decomposing zinc acetate in air at 400 0 C for 12 hrs. The X-ray diffraction (XRD) result indicates that the synthesized ZnO NPs is pure and single crystalline structure with wurtzite type. The crystallite size of the ZnO nanoparticles is in the range of 20–50 nm and average crystallite size of synthesized nanoparticles is found to be ~33 nm. The synthesized ZnO NPs exhibits several photoluminescence peaks centered at 396 nm, 418 nm, 441 nm, 481 nm and 522 nm. The time-resolved rise and decay of photocurrent spectrum shows initial significant increase in photocurrent and, subsequently falls gradually under UV-illumination. The photocurrent abruptly falls when illumination is turned off. The variation of photo and dark-current with applied field is found to follow power-law i.e I α V. At low voltage the behavior is sub-linear which becomes super-linear at high voltages. The ZnO NPs is found to have double traps of 0.59 eV and 0.67 eV.

Effect of KBF4 and K2TiF6 on precipitation kinetics of TiB2 in aluminium matrix composite

N.B. Dhokey; S. Ghule; K. Rane; R.S. Ranade

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 210-216
DOI: 10.5185/amlett.2010.12192

Aluminium reinforced with TiB2 is an emerging class of metal matrix composites for many engineering applications such as automobiles, aerospace and naval vessels. The initial part of the present work study involves melting of individual fluxes of KBF4 and KTiF6 in premelted aluminium in an induction furnace. In the later part of the work covers the combined effect of these fluxes to produce aluminium metal matrix composites containing 2.5% TiB2. The effect of the varying amount of KBF4 on kinetics of TiB2 formation and elimination other unstable phases was studied. The material was examined for hardness, microstructures and wear rates using Pin-on-Disc test machine, XRD and SEM-EDX analysis. The effect of TiB2 on properties was analysed. It was concluded that an optimum level of KBF4 is needed to get critical population of TiB2 particles in the matrix.

Growth and characterization of ZnO nanorods by microwave-assisted route: green chemistry approach

Faheem Ahmed; Shalendra Kumar; Nishat Arshi; Ram Prakash

Advanced Materials Letters, 2011, Volume 2, Issue 3, Pages 183-187
DOI: 10.5185/amlett.2011.1213

ZnO nanorods with diameter 90-100 nm range (tip diameter~15 nm) and length of about 2 μm have been prepared using microwave irradiation technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicate that the nanorods have single phase nature with wurtzite structure and preferentially grow along [0001] direction. Raman spectrum shows the mode E2 high at 439 cm −1 that is related to the vibration of oxygen atoms in wurtzite ZnO. Room-temperature ultraviolet-visible (UV-vis) absorption spectrum shows the absorption band at around 399 nm (red-shifted as compared to bulk). This novel nanostructure would be a promising candidate for a variety of future applications.

Structural, Optical And Gas Evolution Studies Of 60 MeV Si5+ Ion Irradiated PoT-PVC Blends

Advanced Materials Letters, 2011, Volume 2, Issue 2, Pages 125-130
DOI: 10.5185/amlett.2010.1214

Swift Heavy Ion (SHI) irradiation induces chemical and structural changes in polymers by evolving various gases and gaseous fragments. The evolution of gases as a result of chain scissoring and bond breaking leads to cross-linking and cluster formation. Study of the evolved gases helps in understanding the various chemical and structural changes occurring within the polymer under the effect of SHI irradiation. In the present work, Poly (o-toluidine) (PoT), a derivative of polyaniline, is prepared by chemical oxidation polymerization and is blended with polyvinylchloride (PVC) to achieve self supported films. These PoT-PVC blend films were irradiated by 60 MeV Si 5+ ions at different fluences and evolved gases were monitored on-line by Residual Gas Analyzer (RGA). Pre and post irradiation FTIR, UV-Visible absorption and XRD studies have been carried out on these films to observe the changes in chemical/structural and optical properties. An effort has been made to correlate the evolved gases and structural properties after irradiation.Copyright © 2011 VBRI press.

Studies On Characterization Of Corn Cob Based Nanoparticles

Advanced Materials Letters, 2010, Volume 1, Issue 3, Pages 246-253
DOI: 10.5185/amlett.2010.9164

Corn cobs (central part of maize) are either treated as waste or burnt as fuel causing environmental concern. In order to achieve its value addition in new research areas, corn cob can be processed chemically to find ways to generate new end products with added values at very low price. Cellulose-based nanoparticles (CPNs) have an ability to remain intact in stomach environment and small intestine together with the presence of specific enzymes produced by cellulytic bacteria (ruminococus) for colon biodegradability and makes this biopolymer a suitable raw material for the biomedical field, particularly as a colon-specific drug carrier. Cellulose-based nanoparticles (CPNs) were prepared from corn cob raw material by treating it with sodium hydroxide in the range 0-24% of sodium hydroxide concentration, oven dry basis at 165oC for 1.5 h at liquor to solid ratio of 4.5:1. The sample obtained at the optimised condition (18% NaOH concentration, oven dry basis of raw materials) was washed with deionised water, disintegrated and filtered through 80 mesh screens. Powder thus obtained was delignified by acidified sodium chlorite and dried in a vacuum oven to constant weight. Dried powder was further separated by 270 mesh screens. An average particle size approximately equal to 22 nm was obtained by using Transmission Electron Microscopy (TEM). Its crystallinity, functional group and agglomerated particle size was determined by X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) and Scanning Electron Microscopy (SEM) techniques respectively.

Study Of Structural And Electrical Properties Of Pure And Zn-Cu Doped SnO2

Radheshyam Rai

Advanced Materials Letters, 2010, Volume 1, Issue 1, Pages 55-58
DOI: 10.5185/amlett.2010.3101

Numerous metal oxide semiconductor materials were reported to be usable as semiconductor gas sensor, such as ZnO, SnO2, and TiO2 and so on. The samples of Zn and Cu doped SnO2 (SnZnO3 and SnCuO3) have been synthesized by solid-state reaction method. Some aspect of crystal structure of the compound at room temperature was studied using X-ray diffraction technique. The XRD study of the compound shows that there is a change in the basic crystal structure of SnO2 on substitutions of ZnO and CuO. The patterns of the SnO2 sample are indexed as tetragonal perovskite type with a = 7.3928 Å, c = 5.2879 Å but on substitution of ZnO and CuO the structure becomes orthorhombic with lattice constant a = 23.5237Å, b = 8.2183 Å and c =5.8017 Å or a = 21.8594 Å, b = 5.3200 Å, and c = 5.1803 Å, respectively. The temperature variation of resistance shows that compounds have negative temperature coefficient of resistance. The gas sensitivity for LPG (liquefied petroleum gas) showed a drastic change in conductivity.