Volume 4, Issue 11, November 2013


Indian Materials Congress®

Ashutosh Tiwari

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 797-797
DOI: 10.5185/amlett.2013.11001

We are pleased to announce Indian Materials Congress® (IMC). It will be an annual event organised by Vinoba Bhave Research Institute, India during 08-11 December each year from 2014. The goal of congress is to provide a global platform for Indian researchers and engineers coming from academia and industry to present their research results and activities in the field of fundamental and interdisciplinary research of materials science.

State-of-the-art Of Chemically Grown Vanadium Pentoxide Nanostructures With Enhanced Electrochemical Properties

Dimitra Vernardou

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 798-810
DOI: 10.5185/amlett.2013.5485

This review begins by the principles that describe the intercalation properties of vanadium pentoxide. Recent developments in the chemical synthesis of vanadium pentoxide nanostructures including nanorod and nanotube arrays, nanowires, anhydrous and hydrous nanorolls and nanobelts, nanoribbons, nanocables and gels are examined. The objective of this review is to demonstrate the use of these nanostructures as cathodes for lithium batteries and electrochromics with high storage capacity and rate performance due to the large surface area and short distance for charge transport compared to the thin film cathodes.

Quantum Dots For Diagnosis Of Cancers

Pragati Malik; Sunita Gulia; Rita Kakkar

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 811-822
DOI: 10.5185/amlett.2013.3437

The most widely researched and investigated disease, both medically and scientifically, in the current era is the formidable disease cancer. The chances of successful treatment and hence the curability increases if it is diagnosed at an early stage. This can be done only by increasing awareness amongst people about its early diagnosis and screening tests. Cancer screening exams refers to the medical tests to identify people who have disease, often before symptoms of the illness occur. These tests help detecting cancer at its earliest stage when the chances for curing the disease are greatest. Advancements in nanotechnology have made the early screening of cancer possible. In this review, we have discussed the developments in nanotechnology that have encouraged the more recent innovative solutions for early diagnosis and treatment of cancer. Quantum dots, nanometer-sized semiconductors, are the new class of novel biosensors, now being exclusively employed as alternative fluorescent probes due to their unique properties, such as intense and stable fluorescence for a longer time, resistance to photobleaching, large molar extinction coefficients, and highly sensitive detection, due to their ability to absorb and emit light very efficiently. Their size approximates that of individual biomolecules, which offers unique possibilities for the ultrasensitive detection of cancer in persons’ serum, tissues, and other body fluids, when tagged with specific antibodies against specific tumor markers. In this review, we have account briefly the applications of semiconductor QDs employed for the early screening and diagnosis of cancer biomarkers between the years 2009-2012. We believe that this review will enable workers in the field to devise new applications of these materials for the early detection of cancer, and ultimate reduction in incidence of the disease.

A Study On Correlation Between Strain Effect And Conduction Mechanism Of La0.9Ca0.1MnO3 Films

S. Uthayakumar; P. Santhosh; G. H. Aydogdu; H. -U. Habermeier

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 823-826
DOI: 10.5185/amlett.2013.3436

Thin films of La0.9Ca0.1MnO3 with thicknesses in the range of 40-200 nm grown on (100) SrTiO3 employing pulsed laser deposition (PLD) technique have been investigated by measuring structure and transport properties. The structural properties of the films were studied by X-ray diffraction (XRD) technique employing 2ï

Experimental And Numerical Investigations On Fracture Behavior Of High Silica Glass/satin Textile Fiber Reinforced Hybrid Polymer Composites

P.S. Shivakumar Gouda; Krishnaraja G. Kodancha; Dayananda Jawali

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 827-835
DOI: 10.5185/amlett.2013.3450

The fracture behavior of a high silica glass-satin textile fiber reinforced hybrid polymer composite (HPC) under the full range of in-plane loading conditions has been investigated experimentally and numerically. Loading conditions from pure mode- I, through various mixed mode I/II ratios up to pure mode II have been generated by the aid of the proposed compound version of the CTS (compact tension shear) specimen. From the experimentally measured critical loads, the mode I, mode II and the various mixed mode I/II critical stress intensity factors at crack initiation have been determined by the aid of finite element analysis. Based on these results the parameters for a fracture criterion for the composite under consideration have been determined. After testing, both edges of the sample and the fracture surfaces were examined with a scanning electron microscope (SEM). The results infer that the ascendancies of Mode-I and Mode –II are highly dependent on loading angle (LA).

Growth Of Tin Catalyzed Silicon Nanowires By Electron Beam Evaporation

R. Rakesh Kumar; K. Narasimha Rao; K. Rajanna; A. R. Phani

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 836-840
DOI: 10.5185/amlett.2013.3449

Silicon nanowires were grown on tin (Sn) coated Si substrates using electron beam evaporation technique at a growth temperature of 350°C. The as grown Si nanowires were characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscopy attached with Energy Dispersive X-Ray Analyser (TEM-EDX) for their morphological, structural, and compositional properties, respectively. The grown Si nanowires were randomly oriented on the substrate with a length of ~ 500 nm for a deposition time of 15 min. Silicon nanowires have shown tin nanoparticle (capped) on top of it confirming the Vapor-Liquid-Solid (VLS) growth mechanism responsible for Si nanowires growth. The nanowire growth rate was measured to be ~30 nm/min. Transmission Electron Microscope (TEM) measurements have revealed single crystalline nature of Si nanowires. The obtained results have indicated good progress towards finding alternative catalyst to gold for the synthesis of Si nanowires.

Enhanced White Light Emission And Energy Transfer Studies Of Dy3+/Ce3+ Co-doped YAl3(BO3)4 Phosphors For White Light Emitting Diodes

G.V. Lokeswara Reddy; L. Rama Moorthy; T. Chengaiah; B.C. Jamalaiah

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 841-848
DOI: 10.5185/amlett.2013.3453

We reported the structure, photoluminescence and energy transfer studies of Dy 3+ /Ce 3+ co-doped YAl3(BO3)4 (YAB) phosphors prepared by solid-state reaction method at 1200 o C/3h. Upon 273 nm UV excitation, the YAB:Ce 3+ phosphor exhibits a sharp emission band with peak maximum at 380 nm related to the parity and spin allowed Ce 3+ : 5 d → 4 f transition. When excited with 352 nm, the broad emission band of Ce 3+ contains two components at 390 and 417 nm due to the electric dipole transitions from 5d excited state to the two splitting ground 2 F5/2,7/2 states, respectively. The incorporation of Ce 3+ enhances the luminescence intensity of Dy 3+ due to efficient energy transfer from Ce 3+ to Dy 3+ . The emission spectra of Dy 3+ /Ce 3+ co-doped phosphors under 273 nm excitation display the Dy 3+ : 4 F9/2 → 6 H15/2,13/2,11/2 and the Ce 3+ : 5 d → 4 f transitions. The emission colour can be tuned from blue-to-white as a function of Ce 3+ concentration and/or excitation wavelength. Colour perception has been analyzed by evaluating the Commission International de I’Eclairagein (CIE) chromaticity coordinates. The YAB:Dy 3+ /Ce 3+ phosphors can be significant for current generation UV excited white light emitting diodes.

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.

AC Conductivity And Battery Application Of Polyethylene Oxide/PANI/sodium Chlorate Composites

Kunteppa H; Ameena Parveen; H. G. Harish Kumar; Aashis S. Roy

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 856-861
DOI: 10.5185/amlett.2013.3444

Polymer electrolytes based on polyethylene oxide complexes with conducting polyaniline (PANI) and a salt of sodium chlorate has been prepared in different weight percentage ratios. The complexation is confirmed by FTIR spectroscopy and morphology study by employing SEM. AC conductivity measurements are carried out by using LCR Q meter at room temperature. Electrochemical cell parameters for battery applications at room temperature are also determined. The composites PP < sub>5, N3 and N4 show good conductivity which is due to ionic polarization and electrode polarization. Among all these composites N3 shows highest conductivity which is also well understood through the SEM studies. PP < sub>5 shows more conductivity than all the other composites except N3 as because PANI when mixed with PEO gives more feasibility of matrix’s for fast mobility of ions through it easily. The samples are fabricated for battery applications in configuration of Na: (PEO: PANI: NaClO4): (I2 + C + sample) and their experimental data are measured using the Wagner polarization technique.

Local Electronic Structure Of Heavy-ion Irradiated Nano-crystalline Stoichiometric La0.8Sr0.2Mn0.8Fe0.2O3 Particles Using Highresolution Mössbauer Spectroscopy

Usha Chandra; K. Asokan; V. Ganesan

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 862-868
DOI: 10.5185/amlett.2013.4455

Nanocrystalline stoichiometric La0.8Sr0.2Mn0.8Fe0.2O3 manganites synthesized by sol gel technique were irradiated by 200 MeV Ag +16 ion beam at various fluences and investigated by X-ray diffraction (XRD), magnetization and high resolution Mössbauer spectroscopic techniques. The analysis of Mössbauer patterns were done using Kopcewicz et al. (2004) proposition considering Double exchange mechanism. Both XRD and Mössbauer spectroscopic analysis indicated isostructural vacancy formation at Mn site at the fluence 5x10 12 ions/cm 2 . The system showed amorphous phase at the higher fluence of 1x10 13  ions/cm 2 . The local electronic environments seen through high resolution Mössbauer spectroscopic technique on the irradiated systems were understood in terms of ferromagnetic coupling between different Mn environment surrounding Fe ions. This proposition is supported by enhanced magnetization observed in the irradiated samples (Kopcewicz et al., 2004). The similarity to the hydrostatic applied pressure (at low value) is seen through the transformation from Fe 4+ to Fe 3+ at low fluence.

Spectroscopy And Structural Study On CdSe Thin Films Deposited By Chemical Bath Deposition

M. P. Deshpande; Nitya Garg; Sandip V. Bhatt; Pallavi Sakariya; S. H. Chaki

Advanced Materials Letters, 2013, Volume 4, Issue 11, Pages 869-874
DOI: 10.5185/amlett.2013.4467

Cadmium selenide (CdSe) thin films were prepared by chemical bath deposition technique on glass substrates using cadmium acetate dihydrate as a source of Cd 2+ ions, and sodium selenosulphate as a source of Se 2- ions respectively. Triethanolamine and ammonia were used as complexing and pH controlling agent. Films were deposited at different bath temperatures ranging from room temperature to 80 o C while the pH value was kept constant around 10.50 ±0.10. We determined elemental composition of deposited film by X-ray photoelectron spectroscopy. Optical properties of films deposited at different bath temperatures are studied by absorption spectra and parameters like thickness, band gap and absorption coefficient were calculated from the optical transmission spectra. The optical spectra showed a small blue shift and the band gap was found to be greater than the bulk phase. Raman measurements performed at room temperature using Helium-neon laser and Argon laser confirmed the presence of longitudinal optical phonon modes. The selected area electron diffraction pattern for CdSe thin films indicated that they are having mixed nature i.e. both single crystalline and polycrystalline nature with planes of diffraction rings corresponding to cubic structure of CdSe respectively.