Keywords : TEM

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.

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.

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.

Effect of charge transfer band on luminescence properties of Yb doped Y2O3 nanoparticles

Pratik Deshmukh; S. Satapathy; Anju Ahlawat; Khemchand Sahoo; P. K. Gupta

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 458-464
DOI: 10.5185/amlett.2017.6560

The photoluminescence properties of Yb doped Y2O3 nanoparticles were investigated in visible region to resolve the origin of dissimilar fluorescence peaks at different excited wavelengths and to explore possible use of Yb: Y2O3 for white light emission, excited by available near UV LED. The peak observed at 370 nm in photoluminescence excitation spectrum is due to expected transition of electrons from 2 F7/2 to charge transfer band (CTB) associated with non-centrosymmetric C2 centers however, the excitation peak at 335 nm is due to transition of electrons from 2 F7/2 to the CTB associated with distorted centrosymmetric C3i centers. The Yb doping in nano Y2O3 not only modify the CTB but also helps in transition of electron from these CTBs to ground 2 F5/2 and 2 F7/2 levels of Yb. Strong broad emission peak is observed at 503 nm which is assigned to transition from distorted CTB (C3i) to 2 F5/2 energy levels. The findings are important because broad emission (from ~400 to ~650 nm) at 335 nm excitation (available AlGaN LED wavelength) due to C2 and C3i centers in Yb: Y2O3 may be used for white light emission applications.

Synthesis Of High Purity ϒ-lithium Aluminate By Freeze Drying

A. C. Nascimento; M. E. Queiroz;N. D. S. Mohallem

Advanced Materials Letters, 2016, Volume 7, Issue 4, Pages 267-270
DOI: 10.5185/amlett.2016.6126

γ-LiAlO2 plate-like nanostructures have been synthesized by lyophilization of a gel precursor prepared by coprecipitation process. Aqueous solutions of Al(NO3)3.9H2O and LiNO3 were used as precursors, and NaOH was used as precipitant agent. After freeze-drying, the samples were calcined at several temperatures for characterization. The lyophilization process allowed the preparation of γ-LiAlO2 phase at 750 °C, which remained stable until temperatures about 1150 ºC, without the formation of other undesired phases as LiAl5O8. 

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.

Formation And Stabilization Of ZnO Nanoparticles Inside MCM-48 Porous Support Via Post-synthetic Organometallic Route

Mahuya Bandyopadhyay; Hermann Gies; Wolfgang Gr

Advanced Materials Letters, 2015, Volume 6, Issue 11, Pages 978-983
DOI: 10.5185/amlett.2015.5963

The interpenetrating 3-dimensional channel system of silica MCM-48 has been selected for the deposition of ZnO nanoparticles. The post-synthetic organometallic route was employed to load the mesoporous silica with ZnO-precursor molecule. Calcination of the composite transformed the organometallic sorbate to the corresponding metal oxide. X-ray powder diffraction, N2-Adsorption and TEM measurement have supported the efficient loading and growth of ZnO particles in the channels of mesoporous silica matrix. EXAFS analysis (ZnK-edges) also complemented the metal uptake. Presence of nano-dispersed and nanosized ZnO particles confined by the mesoporous pore system was established by TEM and EXAFS analysis.

Synthesis Of Nickel Nanoparticles: Microscopic Investigation, An Efficient Catalyst And Effective Antibacterial Activity

Ratiram Gomaji Chaudhary; Jay A. Tanna; Nilesh V. Gandhare; Alok R. Rai; Harjeet D. Juneja

Advanced Materials Letters, 2015, Volume 6, Issue 11, Pages 990-998
DOI: 10.5185/amlett.2015.5901

Nickel nanoparticles (Ni NPs) with a crystalline size of around 30 nm have been synthesized successfully via the chemical reduction method. Ni NPs were obtained through a nickel salt with hydrazine hydrate at 80 °C temperature by using ethylenediamine as protective agent. The synthesized nanoparticles were characterized by using FTIR spectroscopy, powder X-ray diffraction pattern, ultraviolet-visible spectroscopy, energy dispersive X-ray spectroscopy (EDS), thermogravimetry (TG/DTG), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The size and morphology behavior of NPs were studied by PXRD, SEM and TEM techniques. Furthermore, its applications studies were carried out as catalyst for Knoevenagel condensation reaction of aromatic aldehydes and malononitrile under solvent free conditions. The efficacy of NPs catalyst was exhibited an excellent recyclability and reusability up to four times without any additional treatment. The silent feature of nickel nanoparticles were found as efficient, cleaner reactions profiles and simple workup. Moreover, its comparative antibacterial activities were performed by using common solvents and sonication under standard method. The antibacterial activities were tested against human bacterial pathogen such as Staphylococcus aureus, Escherichia coli, Klebsiella sp, Enterococcus faecalis and Pseudomonas aeruginosa using well diffusion method. Nonetheless, the antibacterial activities of Ni nanoparticles (20 to 60 ug) were compared with four well known antibiotics i.e. Amikacin (30 mcg), Ciprofloxacin (5 mcg), Gentamicin (5 mcg) and Norfloxacin (10 mcg). The highest antimicrobial activity of Nickel nanoparticles were found against Pseudomonas aeruginosa, Staphylococcus aureus (21 mm) and Klebsiella sp. (20 mm). However, the results reveal an efficient antimicrobial activity against pathogenic bacteria under sonication than common solvent technique.

Synthesis Of Al And Ag Nanoparticles Through Ultra-sonic Dissociation Of Thermal Evaporation Deposited Thin Films For Promising Clinical Applications As Polymer Nanocomposite

Narendra Kumar Agrawal; Ravi Agarwal; Divya Bhatia; Divya Saxena; Garima Kedawat; K.C. Swami; Y.K. Vijay

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 301-308
DOI: 10.5185/amlett.2015.5625

Nanoparticles (NPs) having well-defined shape, size and clean surface serve as ideal model system to investigate surface/interfacial reactions. Ag and Al NPs are receiving great interest due to their wide applications in bio-medical field, aerospace and space technology as combustible additives in propellants and hydrogen generation. Hence, in this study, we have synthesized Ag and Al NPs using an innovative approach of ultra-sonic dissociation of thin films. Phase and particle size distributions of the Ag and Al NPs have been determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thin film dissociation/dissolution mechanism, hence conversion into NPs has been characterized by SEM- scanning electron microscope. EDXA & ICPMS have been performed for chemical analysis of NPs. Optical properties have been characterized by UV-Vis and PL spectroscopy. These NPs have also been investigated for their anti-bacterial activity against Escherichia coli bacteria. To the best of our knowledge, this is the first time when NPs has been synthesized by ultra-sonic dissociation of thin films. As an application, these NPs were used further for synthesis of nanocomposite polymer membranes, which show excellent activity against bio film formation.  

Ag Nano-composite Glasses Synthesized By Swift Heavy Ion Irradiation

Ranjana S. Varma; D.C. Kothari; S. Santra; R.G. Thomas; R. Tewari; S. Neogy; C.S. Suchand Sandeep; Reji Philip; D. Kanjilal

Advanced Materials Letters, 2015, Volume 6, Issue 4, Pages 348-353
DOI: 10.5185/amlett.2015.5715

In the present work, we have used swift heavy ions (SHI) irradiation and post irradiation annealing to synthesize Ag nanoparticles in fused silica. Fused silica samples deposited with 15 nm of Ag film were irradiated using SHI beam of 120 MeV Ag 9+ ions at different fluences and post irradiation annealing was done at 500 °C in air for 30 min. The samples were characterized using UV-vis absorption spectroscopy, Rutherford Backscattering Spectrometry (RBS), GAXRD, Transmission Electron Microscopy (TEM), and open aperture z-scan measurements. The signature of Ag nanoparticles was observed in optical absorption spectra and the average size of the Ag nanoparticles was estimated using Mie’s theory. The size of the nanoparticles (~3 nm) was also confirmed from the GAXRD and TEM measurements. RBS results for Ag/SiO2 irradiated with the fluence of 5 x10 13 ions/cm 2 shows the decrease in slope at the interface of the Ag profile, indicating a partial mixing at a fluence of 5 x10 13  ions/cm 2 . Open aperture z-scan measurement of Ag/SiO2 SHI irradiated sample after annealing shows a saturation behavior, indicating that the sample is optically non-linear. The sample shows saturation behavior but does not show optical limiting behavior, which indicates that the size and number density of nanoparticles are low. The ability to control the particle size using ion beam technique as a function of fluence and observed nonlinearity results provide concrete evidence that Ag nano composite glasses can be used in nonlinear and optical limiting application.

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.

On The Molecular Basis Of Silica Gel Morphology

Agnieszka Kierys; Jacek Goworek; Michal Rawski; Istvan Halasz

Advanced Materials Letters, 2015, Volume 6, Issue 1, Pages 40-46
DOI: 10.5185/amlett.2015.amwc1194

Distinction between molecular constitutions of differently made silica gels succeeded only recently.  This paper seeks relationship between the different molecular structures of acid and base set gels and their morphology and pore structure.  Gels were fabricated from both tetraethyl orthosilicate, TEOS, in organic solvent environment and from an economically more desirable, commercial, aqueous Na-silicate solution.  When their gelling was performed in the pores of an organic resin, Amberlite, further molecular differences were observed, along with associated morphology and porosity differences.  We present here unprecedented atomically resolved TEM pictures that visually prove that the molecular structures of gels deduced from their 29 Si NMR and Raman spectra are real, which could also be demonstrated by computer models.

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.

High Stability Field Emission From Zinc Oxide Coated Multiwalled Carbon Nanotube Films

Rajkumar Patra; Santanu Ghosh; Himani Sharma; Vasant D. Vankar

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 849-855
DOI: 10.5185/amlett.2013.4465

A comparative study of electron field emission (FE) property of pristine mutiwalled carbon nanotubes (p-CNTs), zinc (Zn) coated CNTs (Zn-CNT), zinc oxide (ZnO) coated CNTs (ZnO-CNT) is reported. CNTs were synthesized on p-type Si (100) by microwave plasma enhanced chemical vapor deposition (MPECVD) method and the sample was divided into three parts. On two of these parts, a thin layer (~ 4nm) of Zn film was deposited. One of these (Zn-CNT) was kept for analysis and the other one was annealed in oxygen (O2) atmosphere at 520° C for 60 minutes to get ZnO coated CNT film (ZnO-CNT). Scanning electron microscope (SEM) analysis confirmed CNT formation as well as Zn and ZnO coating on the top of p-CNT films. Further, energy-dispersive X-ray spectroscopy (EDX) results confirmed the presence of zinc and oxygen in these two samples. A detailed field emission study performed in these films give following results: (i) lowest turn-on field (electric field required to produce 10 μA/cm 2 current density) and threshold fields (electric field required to produce 100 μA/cm 2 current density) for pristine sample (3.3 V/μm and 5.1 V/μm respectively), followed by ZnO-CNT sample (3.7 V/μm and 6.3 V/μm respectively); (ii) highest temporal stability in current density versus field (J-E characteristics) in ZnO-CNT film as compared to other two, (iii) highest field enhancement factor in ZnO-CNT films as compared to other two. The FE results are correlated with microstructures of the samples as revealed by micro-Raman spectroscopy and transmission electron microscopy (TEM) studies.

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.

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.

Synthesis, Characterization And Nonlinear Optical Properties Of Laser-induced Au Colloidal Nanoparticles

R. Kuladeep; L. Jyothi;D. Narayana Rao; K. Shadak Alee

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 482-487
DOI: 10.5185/amlett.2012.ib.117

Gold (Au) colloidal nanoparticles (NPs) have been synthesized by direct irradiation of gold precursor (HAuCl4) solution in polyvinyl alcohol (PVA) matrix using nanosecond laser pulses at different irradiation fluencies and exposure times. Appearance of wine and dark wine colors indicated the formation of Au NPs. Transmission electron microscope (TEM) images exhibited spherical shaped particles and X-ray Diffraction (XRD) pattern confirms polycrystalline nature of Au NPs with cubic structure. Au NPs displayed negative nonlinearity and exhibited a shift from saturable absorption (SA) at lower intensities to reverse saturable absorption (RSA) accompanied by nonlinear scattering at higher excitation intensities in nanosecond regime at 532 nm. Two-photon absorption (TPA) is attributed to be responsible for the RSA behavior.

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.

Co And Fe Doped SnO2 nanorods By Ce Co-doping And Their Electrical And Magnetic Properties

Jasneet Kaur; Jaspreet Kaur; R. K. Kotnala; Vinay Gupta; Kuldeep Chand Verma

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 511-514
DOI: 10.5185/amlett.2012.icnano.142

In the present work, the self-assembly of Co 2+ and Fe 3+ doped SnO2 nanoparticles (Co and Fe = 5 mol% each) into nanorods by co-doping of Ce 3+ (4 mol%) ions is studied. The nanorods are prepared by a chemical route using polyvinyl alcohol as surfactant with the composition Sn0.91Co0.05Ce0.04O2 (SCC54) and Sn0.91Fe0.05Ce0.04O2 (SFC54). The X-ray diffraction (XRD), transmission electron microscopy (TEM), magnetic and electrical measurements are used to characterize these nanorods. The XRD pattern show the tetragonal rutile and polycrystalline nature of SnO2 nanorods which is also confirmed by TEM. The TEM images exhibit that the diameter of SCC54 nanorods lie in the range of 15-20 nm, length~100-200 nm whereas for SFC54 specimen, diameter ~5-15 nm and length ~50-100 nm. In our previous work, we fabricated Co and Fe (3 and 5 mol% each) doped SnO2 nanoparticles which exhibited high ferromagnetism. It is observed that on Ce 3+ co-doping, nanoparticles assembled themselves into rod like structures and the values of saturation magnetization and dielectric properties have further enhanced. Thus the nature and the concentration of dopants are found to play crucial role in tuning the morphology, magnetic and electrical properties of nanostructures. The values of saturated magnetization (Ms) are 1.14 and 0.14 emu/g and coercive field are 112 and 42 Oe, in SCC54 and SFC54 specimen, respectively, at room temperature. The variation in dielectric behavior is attributed due to the interface polarization. However, in lower frequency regime, the decreasing trend of dielectric permittivity with increasing frequency is explained by the Maxwell-Wagner theory and Koops’ model, whereas, in higher frequency region, the resonant behavior is observed due to nano size effect.

Growth, Characterization And I-V characteristics Of Tin Oxide Nanowires

Anima Johari; M.C. Bhatnagar;Vikas Rana

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 515-518
DOI: 10.5185/amlett.2012.icnano.251

One-dimensional wire shaped tin oxide (SnO2) nanostructures have been synthesized by thermal evaporation method. The growth of SnO2 nanostructure was carried out on gold catalyst layer coated silicon substrate. X-ray diffraction (XRD) results reveals that synthesized SnO2 nanowires have polycrystalline nature with tetragonal rutile structure. SEM, TEM and EDX observation concludes that the uniform SnO2 nanowires (diameter ~ 40 nm and length ~ 50 μm) grow with vapor-liquid-solid (VLS) mechanism. I-V characteristics of single SnO2 nanowire show semiconducting behaviour. Due to structural and electrical properties of SnO2 nanowire, these nanowires would be a promising candidate for gas sensing applications.

Improvement In Ferromagnetism Of NiFe2O4 nanoparticles With Zn Doping

Sukhdeep Singh; R.K. Kotnala;Kuldeep Chand Verma; Manpreet Singh; N.K. Ralhan

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 504-506
DOI: 10.5185/amlett.2012.icnano.226

Structural, microstructural, infrared analysis and magnetic properties of Ni1-x ZnxFe2O4 (NZ) [x = 0.30 (NZ30), 0.35 (NZ35) and 0.40 (NZ40)] nanoferrites have been thoroughly studied. These NZ nanoferrites were synthesized by chemical combustion route and annealed at 500 o C for 5h. Fourier transform infrared (FTIR) spectra of these samples were used to identify formation of Ni-Zn spinel ferrites. These FTIR results show two characteristic absorption bands corresponding to M-O intrinsic stretching vibrations at the tetrahedral site and octahedral-metal stretching around 570-550 cm -1 and 450-435 cm -1 , respectively. The X-ray diffraction shows the polycrystalline with spinel phase of these ferrites. The value of lattice constant a(Å) = 8.370, 8.371 and 8.380 respectively, for NZ30, NZ35 and NZ40 which are consistent with that reported for pure NiFe2O4. The average particles size is measured using Debye-Scherer’s relation which lies in the range of 25-65 nm. Transmission electron microscopy measured average grain size is 26, 41 and 66 nm, respectively for NZ30, NZ35 and NZ40 samples. The magnetic measurement shows saturation magnetization (Ms) of 67.63, 74.97, 80.63 emu/g, remanent magnetization (Mr) 20.01, 25.30, 25.30 emu/g and coercive field (Hc) 154.12, 154.13, 154.11 O e , respectively for NZ30, NZ35 and NZ40. Highest saturation magnetization with Zn doping has been observed in the case of NZ40.

Synthesis And Characterization Of Linear polylactic Acid-based Urethanes Using Tin modified Solid Cloisite-30B Catalyst

Balaji S. Selukar; Sharad P. Parwe; Kavita K. Mohite; Baijayantimala Garnaik

Advanced Materials Letters, 2012, Volume 3, Issue 2, Pages 161-171
DOI: 10.5185/amlett.2011.11325

In recent year, biocompatible, biodegradable materials (linear polylactic acid-based urethanes) in the solid and/or liquid form have attracted tremendous attention in biomedical application particularly in stent coating. Low molecular weight poly (lactic acid) s (PLA), having narrow molecular weight distribution was by dehydropolycondensation method using tetraphenyltin as a catalyst. Hydroxyl terminated linear polylactic acid was prepared reacting PLA with aliphatic diol compounds. The hydroxyl end groups were determined by 31P NMR. PLA oligomers containing both hydroxyl and carboxylic groups were also synthesized by the ring opening polymerization using stannous octoate as an initiator and water as a coinitiator and their structures were confirmed by spectral techniques. The tin modified solid cloisite-30B catalyst was prepared and characterized. The reaction of PLA oligomers and isocyanates (4,4’ methylene bis (phenyldiisocyanate), toluenediisocyanate, 4,4’ methylenebis (cyclohexyldiisocyanate), hexamethylene diisocyanate) was carried out using tin modified solid cloisite-30B catalyst. The effect of the reaction conditions, i.e. the reaction temperature, molar ratio, isocyanates and catalyst on the molecular weight were explored. The structure of the ploymer samples was determined with FT IR, 1H NMR, 13C NMR, matrix-assisted laser-desorption ionization time-of-flight mass spectroscopy (MALDI– TOF MS) and TEM. The present work will highlight the synthesis and characterization of various linear polylactic acid-based urethanes using tin modified solid cloisite catalyst.

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.

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.