Volume 3, Issue 3, July 2012


Editorial

Editorial

Ashutosh Tiwari

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 174-174

We are pleased to publish the 3 volume, 3rd issue, 2012 of Advanced Materials Letters, a quarterly international journal that is intended to provide top-quality peer-reviewed articles in the fascinating field of materials science particularly in the area of structure, synthesis and processing, characterization, advanced-state properties, and applications of materials. The journal publishes review articles, research articles, notes and short communications. The peer-review and proof-ready editing is expected to be completed with-in 3 months and the online version will be published immediately. Advanced Materials Letters is fully committed to publish articles with no page charges and all the published articles are indexed and are available for download for free.

Perspectives Of Fluorescent And Cubic Silicon Carbide

Mikael Syv

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 175-176
DOI: 10.5185/amlett.2012.7002

The world of materials science is a fascinating dimension. Findings in materials which were first made many years ago may lead to new frontiers for energy technologies. In these days of increasingly urgent needs for environmental progress, it is a pleasure for a materials scientist to explore materials concepts with potential advances in energy and environmental, or even biomedical, engineering. Already in 1907 it was observed that there could be light emission from an indirect bandgap material namely, carborundum which is an early name of silicon carbide. This observation is referred to as the first report of a light emitting diode. Now more than 100 years after, the silicon carbide is revisited to make a rare earth metal free white LED for general lighting purpose from new insightful perspectives regarding materials synthesis and growth technology implementation.

Wet-chemical Synthesis Of Spherical Arsenic Nanoparticles By A Simple Reduction Method And Its Characterization

Anjali Pal; Sandip Saha; Sanjoy Kumar Maji; Mainak Kundu; Arpan Kundu

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 177-180
DOI: 10.5185/amlett.2011.9305

his paper has demonstrated, for the first time, the synthesis of yellowish-brown colored stable As(0) sol by borohydride-reduction of aqueous sodium arsenite maintained at pH 7-9 under ambient condition. Scanning electron microscopic (SEM) images reveal the formation of spherical As(0) nanoparticles having size in the range 67?2 nm. The transmission electron microscopic (TEM) studies show the particle size lie within the range 60?3 nm. The X-ray photoelectron spectroscopy (XPS) indicates the zero oxidation state of arsenic. The dynamic light scattering (DLS) studies show that the average particle size is around 45 nm. The absorbance of yellowish-brown As(0) sol at 300 nm shows excellent correlation with arsenic concentration in the range 15.6 – 45.4 ? 10-5 M. The method is simple and reproducible. Also by measuring the turbidity, the quantification of arsenic is possible in the range mentioned. The effects of various ions and temperature on the formation of arsenic nanosol have been reported. The as-prepared As(0) nanoparticles may have potential applications in medicine and sensors.

Microstructure And Dielectric Relaxation Of BT And ST Doped Ba(Fe0.5Nb0.5)O3 ceramics For Sensor Applications

N. K. Singh; Pritam Kumar; Chandra Prakash

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 181-187
DOI: 10.5185/amlett.2012.3325

Recently a new wave of interest has risen on complex perovskite structure due to their wide use in fabrication of multilayer ceramic capacitors, electrostrictive actuators, and electromechanical transducers. The polycrystalline ceramics of Ba(Fe0.5Nb0.5)O3 (BFN) and its solid solutions 0.89Ba(Fe0.5Nb0.5)O3-0.11BaTiO3 (BFN-BT11) and 0.89Ba(Fe0.5Nb0.5)O3-0.11SrTiO3 (BFN-ST11) were fabricated by a solid-state reaction Method. Processing parameters such as calcination temperature, sintering temperature and sintering durations were optimized to get best dielectric properties. It was found that the above ceramics sintered at 1250°C for 6 hours exhibited maximum density and uniform microstructure. X-ray diffraction studies of the compound showed the formation of single-phase monoclinic crystal structure at room temperature. Surface morphology of the compounds was studied by Scanning electron microscope (SEM). The effects of BaTiO3 and SrTiO3 substitution on the structure and on the electrical and ferroelectric properties of Ba(Fe0.5Nb0.5)O3 samples have been studied by performing x-ray diffraction and dielectric measurements. The electrical properties of the samples were investigated in a frequency range of 100 Hz - 1 MHz and temperature range of 30-350 °C using complex impedance spectroscopic technique. The frequency-dependent electrical data are also analyzed in the framework of conductivity and impedance formalisms.

Temperature Dependency And Current Transport Mechanisms Of Pd/V/n-type InP Schottky Rectifiers

S. Sankar Naik; V. Rajagopal Reddy

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 188-196
DOI: 10.5185/amlett.2012.1316

We have investigated the temperature-dependent current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Pd/V Schottky contacts on n-type InP in the temperature range of 200-400 K. The estimated barrier height for the Pd/V/n-type InP SBDs from the I-V and C-V characteristics have varied from 0.48 eV to 0.65 eV (I-V) and 0.85 eV to 0.69 eV (C-V), and the ideality factor (n) from 4.87 to 1.58 in the temperature range 200 to 400 K. It has been observed that the ideality factor decreases while the barrier height increases with increase of temperature. Such behaviour is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the interface. Further, it is found that the series resistance (RS) values of Pd/V/n-InP Schottky diode estimated from Cheung’s function are strongly temperature dependent. The zero-bias barrier height ?bo versus 1/2kT plot has been drawn to obtain the evidence of a Gaussian distribution of the barrier height. The estimated value of ?bo is 0.89 eV with standard deviation σo=145 meV. The mean barrier height and the Richardson constant are determined by the modified Richardson plot ln(Io/T2)-(q2?2o/2k2T2) versus 1/T and are respectively 0.72 eV and 6.59 Acm-2K-2 respectively. Also, the discrepancy between the BHs obtained from the I-V and C-V characteristics is discussed. The interface state densities extracted for the Pd/V/n-InP Schottky diode are in the range of 5.14×10 12 to 3.21×10 12 eV-1cm -2 in the bandgap below conduction band form EC-0.25 to EC-0.51 eV.

Nanaostructured ZnO, ZnO-TiO2 And ZnO-Nb2O5 As Solid State Humidity Sensor

Richa Srivastava;B. C. Yadav

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 197-203
DOI: 10.5185/amlett.2012.4330

Present paper deals with a comparative performance of n-type ZnO, ZnO-TiO2 and ZnO-Nb2O5 nanomaterials as humidity sensors. ZnO was synthesized through hydroxide route. TiO2 and then Nb2O5 were used as additives for improvement of sensitivity. Scanning electron micrograph of ZnO shows rod-like particles with average diameter 40 nm. Structural properties by X-Ray diffraction were studied. The minimum crystallite sizes of ZnO-TiO2 and ZnO-Nb2O5 calculated from Scherrer’s formula were found to be 19 and 17 nm respectively. The pellet of each sensing material was annealed at temperatures 150, 300, 450 and 550 ?C for 3 h and checked for its sensing efficiency. Each heat treated pellet was exposed to humidity under controlled condition and variations in resistance with the humidity were recorded. Comparative study of sensitivities of each sensing element was performed. Average sensitivity achieved was 8 MΩ/%RH for the n-type ZnO annealed at 550 ?C. After chemical mixing of TiO2, the sensitivity increased to 18 MΩ/%RH and after Nb2O5, it was found to be 19 MΩ/%RH. Activation energy of electrical transport and Kelvin radii of each sensing elements were also studied.

On Lattice Distortion By Isovalent Cations In Silver Sulphate Solid Electrolyte

S. W. Anwane

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 204-212
DOI: 10.5185/amlett.2012.4332

Detailed impedance spectroscopic studies are carried out by incorporating various guest iso-valent cations within the solid solubility limit having different ionic radii in Ag2SO4. The solid solubility limits up to x = 3 mole% cation doped Ag2SO4 are set with XRD, SEM, IR and DSC techniques. A major dependence of conductivity on the ionic size of the doped iso-valent cations is observed. The ionic conductivity is found to increase with the incorporation of a guest cation that creates appropriate distortion factor in iso-valent cation doped Ag2SO4. The conductivity of Ag2SO4 is found to be dependent on the ionic size of the guest cation, particularly in the low-temperature modification of Ag2SO4 4 (β-phase). These results could throw light on the fundamental conduction mechanism in Ag2SO4  and also on the criterion of selecting the impurity cation in the classical doping method. The optimized solid electrolytes can then be utilized for their technological applications in electrochemical devices such as SOx sensors and thermal batteries.

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.

Low Temperature Synthesis And Magneto Resistance Study Of Nano La1-xSrxMnO3 (x = 0.3, 0.33, And 0.4) Perovskites

Maneesha Gupta; Poonam Yadav; Wasi Khan; Ameer Azam; Alim H. Naqvi; R. K. Kotnala

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 220-225
DOI: 10.5185/amlett.2012.1309

We have synthesized La1-xSrxMnO3 (with x=0.3, 0.33 & 0.4) perovskite nanoparticles using mild sol-gel technique at low temperature and thereby studied the effect of nanosize on magnetoresistance. These samples were characterized using TGA/DSC, XRD, TEM, FTIR and temperature dependent magnetoresistance (MR) measurements. Powder X-ray diffraction (XRD) result confirms the formation of pure crystalline phase with rhombohedral symmetry in R-3C space group. Crystallite size increases with increase in Sr concentration. TEM analysis further supports the nanosized particles in the samples which lie in the range of 20-30 nm. Fourier transform infrared (FTIR) spectroscopy shows a broad peak at 615 cm -1 for all the samples gives an evidence for the formation of metal oxygen bond organized in to MnO6 octahedral. The steep change in magnetoresistance (MR) at low field at low temperature is observed which is attributed to the alignment of the spins, while in the high field MR is due to the grain boundaries effect at low temperature. In the series studied, 33% Sr doped sample shows higher MR both at low temperature (-17.15) and room temperature (-3.07) than their counter parts.

Transport And Surface Properties Of Molten Al-Mn Alloy

D. Adhikari; I. S. Jha; B. P. Singh

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 226-230
DOI: 10.5185/amlett.2012.3324

The concentration fluctuation in long wavelength limit (SCC(0)) has been computed from experimental data of chemical activity of pure Al and Mn components in molten Al-Mn alloys at 1600K. The SCC(0) is used to obtain Warren-Cowely short range order parameter (α1) and ratio of mutual and intrinsic diffusion coefficients (DM/Did) for this alloy. The surface concentration of pure components with respect to corresponding bulk concentration of pure components for Al-Mn alloy at 1600K has been computed on the basis of Butler’s approach. These surface concentrations are then used to calculate the surface tension for this system.

Synthesis and chracterization of a Tungsten Bronze Ferroeletcric Oxide

B. N. Parida; R. Padhee;R. N. P. Choudhary; Piyush R. Das

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 231-238
DOI: 10.5185/amlett.2012.2321

A new ferroelectric oxide (Li2Pb2Gd2W2Ti4Nb4O30) of the tungsten bronze structural family was synthesized using a high temperature solid-state reaction (i.e., mixed-oxide) method at 1100 o C. Room temperature structural analysis (XRD) shows the formation of a new compound in single phase. The ferroelectric phase transition temperature (much above the room temperature) was determined by the dielectric and polarization measurements. Impedance, modulus and electrical conductivity of the material exhibit a strong correlation between its micro-structure and electrical parameters. The existence of non-exponential-type of conductivity relaxation in the compound was confirmed by detailed studies of its transport properties.

Effect Of Film Thickness On The Structural Morphological And Optical Properties Of Nanocrystalline ZnO Films Formed By RF Magnetron Sputtering

R. Subba Reddy; A. Sreedhar; A. Sivasankar Reddy; S. Uthanna

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 239-245
DOI: 10.5185/amlett.2012.3329

Zinc oxide (ZnO) thin films were formed by RF reactive magnetron sputtering onto p-type silicon and glass substrates held at room temperature. The thickness of the films deposited was in the range 160 – 398 nm. The thickness dependence structural, morphological and optical properties of ZnO films were systematically investigated. The maximum crystallite size of 21 nm observed at films thickness of 231 nm by X- ray diffraction. Scanning electron microscopic analysis revealed that the growth of nanowires in all the films. The root mean square roughness of the films increased from 7.3 to 53 nm in the thickness range of investigation. Fourier transform infrared analysis confirmed the Zn-O bonding located at wavenumber of 413 cm -1 . The average optical transmittance of the films was about 89 % in the visible region. The optical band gap of the ZnO films decreased from 3.14 to 3.02 eV with increase of film thickness from 160 to 398 nm respectively.

Microhardness And Electrical Properties Of PVC/Cu Composites Prepared By Ball Mill

M. G. Kulthe;R. K. Goyal

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 246-249
DOI: 10.5185/amlett.2012.3326

Polymer matrix composites filled with metals are widely studied for the applications in electrostatic dissipation (ESD) and electromagnetic interference (EMI) shielding. In view of this, the electrical conductivity and the microhardness of the polymer matrix composites based on poly(vinyl chloride) (PVC) as matrix and copper (Cu) as reinforcement were determined. The composites were prepared using ball milling followed by hot pressing. Both constituents PVC and Cu were mixed together in a dry condition at room temperature for 12 h, 24 h and 36 h and then blended powder was hot pressed at 175 °C and 50 MPa. The Cu content was varied from 0 to 40 wt% (9.3 vol%) in the matrix. Optical microscope showed good dispersion of Cu particles in the matrix and the degree of Cu dispersion increased with increasing ball milling time. The electrical conductivity of the composites increased approximately six orders of magnitude for 9.3 vol% Cu composite. A percolation threshold was obtained at 3.7 vol% Cu. The microhardness increased by more than 18 % compared to the pure matrix. For a given loading of Cu, the electrical conductivity and the microhardness of the composites increased with increasing ball-milling time. This was attributed to the better and uniform dispersion of the Cu particles in the matrix at higher ball milling time.

Studies On Physical Properties Of Nanostructured ZnO Doped Bi-2223 Superconductors

Indu Verma; Ritesh Kumar;Nidhi Verma

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 250-254
DOI: 10.5185/amlett.2011.9305

Samples of (Bi,Pb)2Sr2Ca2Cu3-xZnxO10+δ (Bi-2223, x=0.0 to 0.30) were synthesized by solid-state reaction route. We carefully synthesized these compounds and characterized them for phase formation, structural/microstructural, electrical and magnetic measurements. The phase identification /gross structural characteristics of synthesized (HTSC) materials explored through powder x-ray diffractometer reveals that all the samples crystallize in orthorhombic structure with lattice parameters a = 0.5405 nm, b = 0.5422 nm and c = 3.7063 nm) up to Zn concentration of x = 0.30. The critical temperature (Tc) measured by standard four probe method has been found to depress from 108 K to 92 K and transport current density (Jc) has been increased from Zn content (x) increases from 0.00 to 0.30. The surface morphology/topography explored by scanning electron and atomic force microscopy (SEM & AFM) shows that microspheres/ nanospheres like structures, voids, grains size & porosity on the surface of the Zn doped Bi-2223 sample increases as the Zn concentration increases. From the magnetic properties measurement (M-H), the ac susceptibility (χac) and the lower (Hc1) & upper (Hc2) critical magnetic field were observed at 10 K from the M-H loop respectively.

Estimation Of Lattice Constants And Type Of Conductivity Of CBD CIAS Thin Films From EDAX Spectra

B. Kavitha;M. Dhanam

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 255-258
DOI: 10.5185/amlett.2011.7287

Near-stoichiometric and stoichiometric CBD CIAS thin films have been prepared onto well-cleaned substrates. EDAX spectra of the prepared thin films enabled to determine the film composition, stoichiometry nature, type of conductivity, lattice constants, volume of the unit cell and density of CIAS thin films. The estimated compositional, structural and electrical parameters are presented and discussed in this paper in detail.

Graft Copolymerization Of Acrylic Acid Onto Gelatinized Patato Starch For Removal Of Metal Ions And Organic Dyes From Aqueous System

Deepak Pathania; Reena Sharma;Susheel Kalia

Advanced Materials Letters, 2012, Volume 3, Issue 3, Pages 259-264
DOI: 10.5185/amlett.2012.3328

The graft copolymerization of acrylic acid onto gelatinized potato starch has been carried out at 70ºC using chromic acid as an initiator. The different reaction parameters such as reaction temperature, initiator and monomer concentrations were optimized to get the maximum percentage grafting. The maximum grafting (93.54%) was observed at 60 ºC, 0.57 molL-1 of acrylic acid and 0.03 mmolL-1 of chromic acid. The grafted samples were evaluated for other physico-chemical properties such as swelling behavior, moisture absorption and chemical resistance. The grafted samples were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) techniques. The graft copolymers have been successfully used for the removal of metal ions and organic dyes from aqueous system.