Keywords : SEM

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.

Nucleation and growth of carbon nanoforms on the surface of metallic plate-substrates and the mechanism of their doping with the clusters of ferromagnetic atoms  

E. Kutelia; L. Rukhadze; T. Dzigrashvili; O. Tsurtsumia; D. Gventsadze

Advanced Materials Letters, 2018, Volume 9, Issue 12, Pages 867-871
DOI: 10.5185/amlett.2018.2144

The present work deals with the special experiments on SEM-EDX study of morphology, chemical composition and topological transformations of the initial ground surface of the bulk iron plate-substrate after its interaction with the ethanol vapor pyrolysis products at high temperatures in the closed-loop and open cycle reactors. Our experiments have shown that the mechanism of formation of Fe clusters-doped CNFs on plate-substrate surfaces may be represented as a process, the first stage of which is a protonation of the substrate subsurface layers caused by diffusion of hydrogen atoms facilitating the formation of 3D nano-groups of Fe atoms assembled in the characteristic clusters with magic numbers of atoms, depending on the thermodynamics of the metal. The spontaneous coalescence of these clusters into giant Fe-clusters at comparatively low temperatures and formation of iron nano-droplets at comparatively high temperatures results in the formation of a nanopatterned surface with the uniformly distributed catalytic centers of CNFs nucleation. The second stage of the process is a nanoparticle-guided growth through the VLS or VS (at low temperatures) growth mechanisms in which the one cluster provides nucleation of only one CNF particle so that the sizes of the nucleation centers determine the basic size of the CNF nanoparticles.

Structure and properties degradation of the nuclear graphite under neutron irradiation

Boris A. Gurovich; Denis A. Kuleshov; Dmitriy A. Maltsev; Oleg K. Chugunov; Alexey S. Frolov; Yaroslav I. Shtrombakh

Advanced Materials Letters, 2018, Volume 9, Issue 11, Pages 781-788
DOI: 10.5185/amlett.2018.2132

The operation of nuclear graphite in graphite-moderated reactors is accompanied by its properties degradation under the influence of neutron irradiation, which limits their service life. In this connection, it is of interest to identify the mechanisms that determine the properties degradation of graphite materials at various operational stages of operating RBMK power reactors.

Study of the properties of La-doped ZnS thin Films synthesized by Sol-gel method

Amel Tounsi; Djahida Talantikite-Touati; Hamid Merzouk; Hadjira Haddad; Roumaïssa Khalfi

Advanced Materials Letters, 2018, Volume 9, Issue 3, Pages 216-219
DOI: 10.5185/amlett.2018.1963

The thin layers of undoped ZnS and ZnS doped La with different concentrations (2, 4, 6, 8 and 10%) were deposited on glass substrates using sol-gel and dip-coating methods. The structural characterization of these samples was carried out by the  X-rays diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). UV-visible and Fourier Transform Infrared spectroscopy (FTIR) have been used to study the effect of dopant on the optical properties of ZnS doped La thin films. Atomic force microscopy images of the films have revealed homogeneous and granular structure and the SEM micrographies show deposit films with uniform and porous structure. The optical transmission spectra in the UV - visible range have shown that all the doped films present a good optical transmission in the visible domain.

Zeolite 4A Filled Poly (3, 4-ethylenedioxythiophene): (polystyrenesulfonate) (PEDOT: PSS) And Polyvinyl Alcohol (PVA) Blend Nanocomposites As High-k Dielectric Materials For Embedded Capacitor Applications

M. K. Mohanapriya; Kalim Deshmukh; M. Basheer Ahamed; K. Chidambaram; S. K. Khadheer Pasha

Advanced Materials Letters, 2016, Volume 7, Issue 12, Pages 996-1002
DOI: 10.5185/amlett.2016.6555

Zeolite 4A nanoparticles were incorporated into Poly (3, 4 - ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) and Polyvinyl alcohol (PVA) blend matrix to prepare PEDOT: PSS/PVA/Zeolite 4A nanocomposites using solution casting technique. The structure and morphology of nanocomposites were examined using Fourier transform infrared spectroscopy, X-ray diffraction, UV-Vis spectroscopy and Scanning electron microscopy. The mechanical and dielectric properties of nanocomposites were also evaluated. The FTIR and XRD results indicate the strong interaction between the Zeolite 4A nanoparticles and the polymer matrix. The SEM micrographs show the homogeneous dispersion of Zeolite 4A into the polymer matrix. The nanocomposite exhibits a high dielectric constant and low dielectric loss, which could be due to proper dispersion and good interaction between Zeolite 4 A and polymer matrix. Thus, based on the results obtained it can be concluded that PEDOT: PSS/PVA/Zeolite 4A nanocomposites can be used as a flexible dielectric material for embedded capacitor applications.

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.

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.

Synthesis And Doping Feasibility Of Composite-hydroxide-mediated Approach For The Cu1-xZnxO Nanomaterials

Tauseef Shahid; Muhammad Arfan; Waqas Ahmad; Tayyaba BiBi; Taj Muhammad Khan

Advanced Materials Letters, 2016, Volume 7, Issue 7, Pages 561-566
DOI: 10.5185/amlett.2016.6384

In this article, we report feasibility of composite hydroxide-mediated (CHM) approach for the synthesis and doping of Cu1-xZnxO (x=0%, 3%, 6% and 9%) nanomaterial. The proposed method offers a low cost, low temperature and environmentally friendly approach to preparing doped nanomaterials in a feasible and cost- effective route. Further, we investigate the effect of incorporated Zn +2 on the properties of produced Cu (II) O nanostructures. The X-ray diffraction analysis confirms formation of the single-phase monoclinic Cu (II) O and incorporation of Zn at the Cu-lattice sites. The crystalline structure is improved and the average grain size has increased from 85.32 nm to 124.86 nm. FTIR spectroscopy shows characteristic vibrational peaks of the Cu (II)-O bonding which confirms formation of the Cu (II) O. SEM micrographs reveal interesting flower like dense features with morphological peculiarities and seems to strongly depend on the content of the incorporated Zn +2 . The UV- visible spectra are measured to study the direct bandgap of the prepared nanomaterial. The direct bandgap found to be in the range of 3.73 - 3.89 eV. The method seems experimentally friendly and provides a feasible and a high productive fast synthesis route for the doped oxide nanomaterials in a single step with tunable properties for the research purposes. However, the method still requires further investigation to finely control doping for the desired properties of a nanomaterial and to give a potential avenue for further practical scale-up of the production process and applications of novel devices based on doped nanostructures.

Synthesis, Characterization And Electrochemical Studies On Novel Li2MZrO4 (M = Fe, Mn) Cathode Material For Lithium-ion Battery

Bikash Mandal; I. Basumallick; Susanta Ghosh

Advanced Materials Letters, 2016, Volume 7, Issue 2, Pages 150-155
DOI: 10.5185/amlett.2016.6089

We report a novel cathode of the molecular formula, Li2MZrO4 (M = Fe, Mn), based on an inexpensive, earth-abundant, and eco-friendly materials, which have theoretical capacities within 119 – 238 mAh.g -1 depending on the number of lithium ions extracted from material, suitable for high power rechargeable lithium-ion battery. X-ray diffraction (XRD) revealed tetragonal crystal structure of the synthesized material. SEM images illustrate the formation of porous material with large surface area.  The cyclic voltammograms of Li2MZrO4 (M=Fe, Mn) showed only one pair of redox peak corresponding to the anodic and cathodic reactions within a potential window of 2.2 – 4.5 volts vs. Li/Li + . The first discharge capacities were 89 mAhg -1 for Li2FeZrO4, whereas in case of Li2MnZrO4 it was 94 mAhg -1 at 0.1 C rates, which are equivalent to removal of one lithium ion from the compounds.

Triangular Si3N4 Nano-scale Pits On The Stepped Si (553) Surface By Ion Induced Reaction   

Amit Kumar Singh Chauhan; Shibin Krishna T.C.; Neha Aggarwal; Monu Mishra; Asad Niazi; Lekha Nair; Govind Gupta

Advanced Materials Letters, 2015, Volume 6, Issue 11, Pages 941-946
DOI: 10.5185/amlett.2015.5894

Triangular nano-scale pits (TNPs) of Si3N4 are fabricated by reactive nitrogen ion sputtering using low energy nitrogen ions on the Si (553) surface at 500 °C. The electronic structure of the developing Si3N4 interface was monitored in-situ by Auger Electron Spectroscopy (AES) while the ion beam induced surface reaction was analysed via X-Ray and Ultraviolet photoemission spectroscopy (XPS & UPS), Photoluminescence and Raman spectroscopy. The morphological development of nanoscale pit structures was observed by Scanning Electron Microscopy (SEM). The formation of Si3N4 was identified by AES, with the appearance of the characteristic reacted Si(LVV) peak at 83 eV, while photoemission spectroscopy confirmed the stoichiometry of Si3N4. The valence band maximum was observed to be located at 2.4 eV below the Fermi level.  SEM images showed uniformly distributed Si3N4 TNPs with size varying between 250 to 600 nm (length) and 200 to 400 nm (width). Our work underlines the influence of ion energy and substrate temperature and establishes the conditions for the growth of Si3N3 TNPs by ion induced reactive sputtering.

Mechanisms Of Composite-hydroxide-mediated Approach For The Synthesis Of Functional ZnO Nanostructures And Morphological Dependent Optical Emissions

Taj Muhammad Khan; M. Zakria; Rana I. Shakoor; M. Raffi; Mushtaq Ahmad

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 592-599
DOI: 10.5185/amlett.2015.5876

We report synthesis of the functional ZnO nanostructures (nanowires, nanorods) by a cost-effective and efficient method; called composite-hydroxide-mediated (CHM) approach. Effect of the processing temperature on the particle size, morphology, and subsequently morphological dependent optical emissions is investigated. Needle-shaped nanowires are obtained at 200 and 220 o C, of about (500-1500) nm in length, while at 250 o C; nanorods are formed with length in the range of (200-460) nm and width (10-30) nm. Optical study reveals that ZnO nanorods show only ultra-violet (UV) emission while bent nanowires demonstrate both UV and green emissions simultaneously. The week green emission at 2.4 eV indicates no efficient trapping of the photo-generated hole in the nanostructures. Phase purity, crystalline structure, size and chemical nature of the product are probed by XRD, EDX, Raman spectroscopy and FT-IR. The particle size estimated from the spatial correlation phonon confinement model for the E2 (high) phonon mode. The applied approach is believed to be efficient, and a direct route for the synthesis of a wide range of simple and complex oxide nanostructures for novel electro-optical nanodevices.

Influence Of TiC Particulate Reinforcement On The Corrosion Behaviour Of Al 6061 Metal Matrix Composites

H. C. Ananda Murthy; Somit Kumar Singh

Advanced Materials Letters, 2015, Volume 6, Issue 7, Pages 633-640
DOI: 10.5185/amlett.2015.5654

Aluminum matrix composites (AMCs), reinforced with ceramic particulates, have significant applications in the field of aerospace, marine, automobiles, sports and recreation. Al-TiC particulate composite has better potential for high-temperature applications. The corrosion behaviour of Al 6061-TiC particulate composites prepared by stir casting route, has been explored in chloride medium using electroanalytical techniques such as Tafel, Cyclic polarization and Impedance measurements (EIS). SEM and EDX analysis of the microstructures obtained in both matrix alloy and reinforced composites were performed in order to know the effect of titanium carbide on the corrosion resistance of composites. The polarization studies reveal an increase in the corrosion resistance in composites compared to the matrix alloy. The observed increase in corrosion resistance of TiC particulate reinforced composites is attributed to excellent bond integrity of TiC particulates with aluminium and possible electrochemical decoupling between TiC particles and Al 6061 matrix alloy. The EIS study reveals that the polarisation resistance (Rp) increase with increase in TiC content in composites and the corrosion process is mainly charge transfer controlled. Titanium carbide is proved to be a potential reinforcement for improved corrosion resistance in Al MMCs.

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.

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.

Green Synthesis Of Gold Nanoparticles From The Leaf Extract Of Nepenthes Khasiana And Antimicrobial Assay

B.S. Bhau; Sneha Ghosh; Sangeeta Puri; B. Borah; D.K. Sarmah; Raju Khan

Advanced Materials Letters, 2015, Volume 6, Issue 1, Pages 55-58
DOI: 10.5185/amlett.2015.5609

Synthesis of nanoparticles from various biological systems has been reported, but among all, biosynthesis of nanoparticles from plants is considered as the most suitable method. The use of plant material not only makes the process eco-friendly but also the abundance makes it more economical. The aim of this study was to investigate the ability of this plant to synthesis gold nanoparticles and study the properties of the nanoparticles thus produced. Antimicrobial activity and medicinal values of Nepenthes khasiana fascinated us to utilize it for biosynthesis of gold nanoparticles. The synthesized gold nanoparticles were characterized by UV-vis spectrophotometry, Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infra-red Spectroscopy and Transmission Electron Microscopy. Different time intervals for the reaction with aqueous chloroauric acid solution increase in the absorbance with time and became constant giving a maximum absorbance at 599.78 nm at three hours of incubation. The results from XRD, TEM and SEM supports the biosynthesis of triangular and spherical shaped Gold nanoparticles between 50nm to 80 nm. In this study, the antimicrobial property of the AuNPS was exploited against human pathogenic micro-organisms. The results of TEM, SEM, FT-IR, UV-VIS and XRD confirm that the leaves extract of N. Khasiana can be used to produce Gold nanoparticles with significant amount of antimicrobial activity.​

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.

Mdification Of Poly(3,4-ethylenedioxy Thiophene)/poly(4-styrene Sulphonate) (PEDOT: PSS)/nanographit Nanocomposite  through Ion Beam Technique

Sunita Rattan; Prachi Singhal; Devesh Kumar Avasthi; Ambuj Tripathi

Advanced Materials Letters, 2014, Volume 5, Issue 12, Pages 712-716
DOI: 10.5185/amlett.2014.nib504

Ion implantation is a surface treatment process in which the surface of a sample is bombarded with a beam of energetic dopant ions to implant ions into the matrix of the substrate. In the present work, nanocomposites of poly(3,4-ethylenedioxy thiophene) /poly(4-styrene sulphonate) (PEDOT: PSS) and nanographite are prepared and subjected to swift heavy ion implantation using the same ion as that of the filler in the nanocomposites. PEDOT: PSS/ nanographite nanocomposites have been synthesized by solution blending method. The prepared PEDOT: PSS/ nanographite nanocomposite films were irradiated with carbon ions (C ion beam, 50 MeV) in fluence range of 3 × 10 10 to 3 × 10 12 ions/cm 2 . The nanocomposite films were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) before and after C ion implantation and were evaluated for their electrical and sensor properties. SEM and XRD studies clearly depict the homogeneous dispersion of nanograhite in polymer matrix along with densification of the polymer nanocomposite. The implanted nanocomposites exhibit better electrical and sensor properties for the detection of nitroaromatics.

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.

Characterization Of Nano-structured Magnesiumchromium ferrites Synthesized By Citrate-gel auto Combustion Method

M. Raghasudha; D. Ravinder; P. Veerasomaiah

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 910-916
DOI: 10.5185/amlett.2013.5479

Nano-ferrites of the composition Mg Crx Fe2-xO4 (where x=0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) were synthesized at a very low temperature (180°C) by Citrate-gel auto combustion method. The as synthesized powders were sintered at 500 0 C for four hours in an air and were characterized by X-ray diffraction (XRD) which confirmed the formation of cubic spinel structure of ferrites. The crystallite size was in the range of 7 to 23nm for different compositions with the significant decrease of ~16nm in response to the increase in Cr substitution. Such low nano sized ferrites are desirable for variety of applications like, in magnetic data storage and in targeted drug delivery, etc. Morphological studies by Scanning Electron Microscopy (SEM) revealed formation of largely agglomerated, well defined nano particles of the sample. Elemental composition characterizations of the prepared samples were performed by Energy Dispersive Spectroscopy (EDS) which shows the presence of Mg, Cr, Fe and O without precipitating cations. The FTIR spectral studies at room temperature in the range of 400 to 800cm-1 showed two strong absorption bands. The high frequency band (ν1) around 600 cm -1 is attributed to the intrinsic vibrations of tetrahedral complexes and the low frequency band (ν2) around 400 cm -1 is due to octahedral complexes. The spectra showed the characteristic peaks of ferrite sample. The observed results can be explained on the basis of composition and crystal size.

Synthesis And Characterization Of CuO Electrospum Nanofiber Using Poly(vinyl Acetate)/Cu(CH3COO)2 Annealing Method

Seema Sharma; Rashmi Rani; Radheshyam Rai; T. S. Natarajan

Advanced Materials Letters, 2013, Volume 4, Issue 10, Pages 749-753
DOI: 10.5185/amlett.2013.2425

One dimensional nanofibers of organic and inorganic materials have been used in filters, optoelectronic devices, sensors etc. It is difficult to obtain ultra fine fibers of inorganic materials having lengths in the order of millimeter as they tend to break during formation due to thermal and other mechanical stresses. In this study, we have investigated the mechanism to prevent the defect formation and the breaking of CuO nanofibers by using optimized heat flow rates. CuO nanofibers were obtained by heat treating the poly(vinyl acetate) PVA composite fibers formed by electrospinning. The morphology and structural characteristics of prepared samples were investigated by Scanning electron microscopy, Transmission electron microscopy and X-ray diffraction. It was found that the morphology of the composite and annealed nanofibers could be influenced by the concentration of the polymer content. A lower concentration favors the formation of defects along the fiber and the number of defects reduces when the concentration is increased.

Plant Mediated Synthesis Of Gold Nanoparticles Using Fruit Extracts Of Ananas Comosus (L.) (Pineapple) And Evaluation Of Biological Activities

Nagaraj Basavegowda; Agnieszka Sobczak-Kupiec; Dagmara Malina; Yathirajan HS; Keerthi V R; Chandrashekar N; Salman Dinkar; Liny P

Advanced Materials Letters, 2013, Volume 4, Issue 5, Pages 332-337
DOI: 10.5185/amlett.2012.9423

AnchorPlant mediated synthesis of metallic nanoparticles is an increasing commercial demand due to the wide applicability in various areas such as electronics, catalysis, chemistry, energy, cosmetics and medicine. In the present investigation, synthesis of gold nanoparticles is done by using fruit extracts of Ananas comosus (L.). Nanoparticles were characterized by using UV visible absorption spectra. Their morphology, elemental composition and crystalline phase were determined by scanning electron microscopy, energy dispersive X-ray spectroscopy and selected area electron diffraction. FT-IR analysis was used to confirm the presence of gold nanoparticles in the extracts. The synthesized gold nanoparticles were generally found to be effective as antimicrobial agents against some important human pathogens like E.coli and Streptobacillus sp. which are affecting and cause diseases like food poisoning and rat-bite fever to human beings respectively.

Surface Modification Of Polyanniline Nanofiber Using Silver nanoparticles To Enhance Sensing Properties

Yasir Ali; A. S. Dhaliwal;R G Sonkawade; Vijay Kumar

Advanced Materials Letters, 2013, Volume 4, Issue 5, Pages 368-372
DOI: 10.5185/amlett.2012.9422

AnchorThe surface of polyaniline nanofibres is modified by silver nano particles using cyclic voltametry (CV). The surface modifications induced by silver particles are confirmed by scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and Raman spectroscopic techniques. The SEM micrographs show uniform distribution of silver particles on the surface of PANI nano fibers. Presence of silver particles was confirmed by EDX. Structural variations induced after reduction of Ag-metal particles and formation of polaron and bipolarons are studied by Raman spectroscopy.

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.

Characterization and Photoluminescence Of Sr2CeO4: Eu+3, La+3

Ch. Atchyutha Rao; Poornachandra Rao V. Nannapaneni; K. V. R. Murthy

Advanced Materials Letters, 2013, Volume 4, Issue 3, Pages 207-212
DOI: 10.5185/amlett.2012.7395

In this paper we report the synthesis and luminescence of strontium cerium oxide (Sr2CeO4:Eu 3+ (0.5mol%),La 3+ (0.5mol%) prepared by solid state reaction method in air at 12000C.These samples were characterized by X-ray diffraction, scanning electron microscope (SEM) and photoluminescence (PL) techniques, particle size analysis. The photo luminescence (PL) spectra of pure and Eu 3+ , La 3+ codoped Sr2CeO4 were recorded at room temperature. Sr2CeO4 phosphor was effectively excited around 250 nm and observed a broad emission band peak around 467 nm. XRD data revealed that the structure of Sr2CeO4 is orthorhombic, and the mean crystallite size of Sr 2CeO4 and Sr2CeO4: Eu 3+ , La 3+ were 9 nm and 11nm respectively. The colour co-ordinates of Sr2CeO4 were x = 0.16 and y = 0.18 and CIE co-ordinates revealed that the present phosphors may be used in white light applications.

A Study On The Electrospinning Behaviour And Nanofibre Morphology Of Anionically Charged Lignin

Makoto Schreiber; Singaravelu Vivekanandhan; Amar Kumar Mohanty; Manjusri Misra

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 476-480
DOI: 10.5185/amlett.2012.icnano.336

The electrospinnability of anionically charged sodium carbonate lignin using positive-voltage electrospinning was explored. The lignin was mixed with polyethylene oxide (PEO) in order to enhance the electrospinning performance by improving the viscoelastic properties. Lignin fibres containing varying concentrations of lignin were obtained by employing various applied voltages. The effect of increased lignin content on the electrospinning behaviour and the obtained fibre morphologies were observed. The electrospun fibres were characterised using scanning electron microscopy (SEM) to investigate their microstructure. SEM analysis showed the formation of well defined lignin fibres and the results indicate that the morphologies are highly depend on the PEO:lignin composition.

Fabrication Of Polyaniline Nanofibers By Chronopotentiometery

Yasir Ali; R G Sonkawade;A S Dhaliwal; Vijay Kumar

Advanced Materials Letters, 2012, Volume 3, Issue 5, Pages 388-392
DOI: 10.5185/amlett.2012.6358

We have electrochemically synthesized polyaniline nano fibers with optimized process parameters (viz. concentration of monomer and dopant, applied current density, deposition time, etc.) on ITO coated glass substrate. The nano fibers of polyaniline were subjected to UV Visible, SEM and Raman spectroscopy. UV Vis spectra show two prominent peaks at 317 and 418 nm, which confirm the presence of different forms of polyaniline. Raman spectra confirm the formation of polyaniline. SEM image of synthesized nano fibers showed a flower like structure with an isotropic growth rate.

A Comparative Analysis Of Structural, Optical And Photocatalytic Properties Of ZnO And Ni Doped ZnO Nanospheres Prepared By Sol Gel Method

Shashi Kant;Amit Kumar

Advanced Materials Letters, 2012, Volume 3, Issue 4, Pages 350-354
DOI: 10.5185/amlett.2012.5344

Zn1-xNixO (x=0, 0.5) nanoparticles were successfully prepared by sol gel method. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. Surface morphology of nanosystems was performed by Scanning Electron Microscopy (SEM) and High Resolution Transmission Emission Microscopy (TEM) .Due to doping of ZnO nanoparticles the absorption shifted towards the visible region from UV region .The absorption increases on doping in the visible region.The Photocatalytic activity of both the doped and undoped ZnO was analysed via degradation of Methylene Blue. The Methylene Blue decomposition rate of pure ZnO and Nickel doped ZnO nanoparticles were studied under UV –Visible region. In the visible region both pure and doped ZnO decomposed Methylene Blue.This confirms the potential application of ZnO Nanoparticles for removal of harmful dyes from waste water and drinking water.The doping has a pronounced effect on the photocatalytic activity of nanoparticles. The degradation rate of the dye increased in case of Ni doped ZnO nanospheres.

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.

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.

Study of Pb(Zr0.65Ti0.35)O3(PZT(65/35) doping on structural, dielectric and conductivity properties of BaTiO3(BT) ceramics

Arun Chamola; Hemant Singh; U.C. Naithani

Advanced Materials Letters, 2011, Volume 2, Issue 2, Pages 148-152
DOI: 10.5185/amlett.2010.11183

(1−x)BaTiO3–xPZT(65/35) ceramics were prepared by high temperature solid state reaction technique. Structural properties of the compounds were examined using an X-ray diffraction (XRD) technique to confirm the formation of phase at room temperature. Detailed studies of dielectric properties of (1−x) BaTiO3–xPZT(65/35) for all compositions were in temperature range 30-200 o C reveal that the compound have transition temperature well above at the room temperature. While pure BaTiO3 ceramics exhibited a sharp phase transformation expected for normal ferroelectrics, phase transformation behavior of the (1−x)BaTiO3–xPZT(65/35) solid solutions became more diffuse with increasing PZT(65/35) contents. The diffusivity of the dielectric peaks in the compound exhibited the values between 1 and 2 where the higher value indicates the greater disorder in the systems. This was primarily evidenced by an increased broadness in the dielectric peak, with a maximum peak width occurring at x = 0.5. The temperature dependence of ac conductivity indicated that the electrical conductivity decrease above Tc on increasing the PZT(65/35) contents. This increase in the conductivity is attributed to the increase in polarizability of the materials around Tc, due to oxygen vacancies.

Optical properties of MAl12O19:Eu (M = Ca, Ba, Sr) nanophosphors

Abhay D. Deshmukh; S. J. Dhoble; N.S. Dhoble

Advanced Materials Letters, 2011, Volume 2, Issue 1, Pages 38-42
DOI: 10.5185/amlett.2010.10171

The MAl12O19:Eu (M = Ca, Ba, Sr) phosphor were synthesized by combustion method and systematically characterized by photoluminescence excitation and emission spectra, concentration quenching, morphology and X-ray mapping with scanning electron microscopy. In SrAl12O19:Eu phosphor two PL emission peaks are observed at about 389 nm and another around 420 nm as well as BaAl12O19:Eu phosphor shows blue emission around 460 nm is observed in the blue region of the spectrum and CaAl12O19:Eu shows only red emission at 592 as well as 615 nm. Both phosphors can be efficiently excited in the wavelength range of 250-425 nm, where the near UV (~320 nm) solid state excitation is matched. By combining MAl12O19:Eu (M = Ca, Ba, Sr) phosphor with near UV chops emitting intense blue green (Ba), yellow-red (Ca) and blue purple (Sr) LEDs white LEDs can be produced.

Structural, dielectric and electrical properties of Lead zirconate titanate and CaCu3Ti4O12 ceramic composite

Arun Chamola; Hemant Singh; U.C. Naithani; Shubhash Sharma; Uday Prabhat; Pratiksha Devi; Anuradha Malik; Alok Srivastava; R.K. Sharma

Advanced Materials Letters, 2011, Volume 2, Issue 1, Pages 26-31
DOI: 10.5185/amlett.2010.12182

In the present work, structural, dielectric and electrical properties of lead zirconate titanate and CaCu3Ti4O12 ceramic composite with composition (1-x)Pb(Zr0.65Ti0.35)O3 - xCaCu3Ti4O12 (where x = 0, 0.20, 0.40 and 0.60) has been reported. The sample was prepared by employing a high-temperature solid-state reaction technique. X-ray diffraction studies confirm the formation of pure phase for x = 0.00 concentration and composite phases for the x = 0.40, 0.60 compositions. Doublet of diffraction peaks suggests structural change for x = 0.20 composition. Scanning electron micrographs show a uniform grain distribution and the grain size and shape modified upon CaCu3Ti4O12 addition. Dielectric measurement demonstrates a decrease in the dielectric constant with increase in CaCu3Ti4O12 percentage. The prepared ceramic composites have high dielectric constant and low dielectric loss. The temperature dependence of the ac conductivity indicated that the conduction process is due to singly ionized (in ferroelectric region) and doubly ionized (in paraelectric region).

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.

Enhancement Of Hydrophobic Character Of Lignocellulosic Fibers Through Graftcopolymerization

Amar Singh Singha;Raj K. Rana

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 156-163
DOI: 10.5185/amlett.2010.6134

Owing to hydrophilic behavior lignocellulosic fibers, e.g. Agave is unacceptable in various fields of applications. In the present communication attempts have been made to enhance hyrdrophobicity of these fibers through surface modification using methyl methacrylate as vinyl monomer. The grafting reaction initiated by ceric ion was carried out in vacuum. The various reaction parameters such as reaction time, temperature, monomer concentration, initiator concentration and vacuum were optimized to obtain the maximum percent graft yield. The grafted samples were evaluated for the hydrophobic character and other physico- chemical properties such as swelling behavior in different polar and nonpolar solvents alongwith chemical resistance behavior. The grafted products were further characterized by different techniques such as FT-IR, SEM, X-RD and thermogravimetric studies.