006443   Sahu N;Panigrahi S (Physics Dep, National institute of Technology, Rourkela-769 008, Email: nsahu76@gmail.com) : Rietveld analysis, dielectric and impedance behaviour of Mn<. Bull Mater Sci 2013, 36(4), 699-708.

The polycrystalline samples of Pb(Zr_0.65-x A_x Ti_0.35)O₃ (A = Mn/Fe), (x =0.00, 0.05) (PZM/FT) were synthesized by conventional solid-state reaction technique. X-ray diffraction (XRD) pattern was recorded at room temperature and the samples were found in single phase form. All the observed peaks could be indexed to R3c space group with rhombohedral symmetry. XRD pattern has been analysed by employing Rietveld method with the help of FullProf Program. The lattice parameters and unit cell volumes decrease from Mn^{3+ to Fe3+ ion concentrations. The bond lengths and angles have been calculated by using Powder Cell Programme. Microstructural analysis of the surface of the ceramic compound by scanning electron microscopy (SEM) exhibits that there is a significant change in grain size on introduction of Mn3+ and Fe3+ ions at the Zr-site of the compound. It is observed that both the substitutions (Mn3+ and Fe3+) at Zr site induce an increase in dielectric constant and a shift in Curie temperature (T_c). From a.c. conductivity analysis, we have estimated the activation energy for both ferroelectric and paraelectric regions. Both the modified samples are obeying Jonscher power law. From Nyquist plots, the activation energy of grain resistance, relaxation time and bulk conductivity are compared. The grain resistance of the material decreases with rise in temperature which indicates a semiconducting behaviour of the material.}

9 illus, 6 tables, 51 ref

006442   Rozati S M;Bargebidi Z (Physics Dep, University of Guilan, Rasht-413 335, Iran, Email: smrozati@guilan.ac.ir) : Characterization of molybdenum-doped indium oxide thin films by spray pyrolysis technique. Bull Mater Sci 2013, 36(4), 553-8.

In this research, indium oxide nanostructure undoped and doped with Mo were prepared on glass substrates using spray pyrolysis technique. Various parameters such as dopant concentration and deposition temperatures were studied. Structural properties of these films were investigated by X-ray diffraction and scanning electron microscopy. Electrical and optical properties have been studied by Hall effect and UV-Visible spectrophotometer, respectively. The thickness of the films was determined by PUMA software. The variation of refractive index, extension coefficient and bandgap of these films also were investigated.

5 illus, 2 tables, 19 ref

006441   Priyanka K P;Sheena P A;Aloysius Sabu N; Varghese T (Physics Dep, Nanoscience Research Centre (NSRC), Nirmala College, Muvattupuzha, Kerala) : Modification on the band gap of nanoceria using 8 MeV electron beam. Sci Soc 2013, 11(1), 5-9.

Cerium oxide nanoparticles or nanoceria, synthesized by using cerium nitrate hexa hydrate [Ce(NO₃)₃.6H2O] and ammonium carbonate as precursors were characterized by transmission electron microscopy and UV-Visible spectroscopy. Using high energy electron beam the surface modification of CeO₂ was carried out. The optical properties of the synthesized nanocrystalline CeO₂ samples and the electron beam irradiated samples were investigated in context of the band gap. The band gap obtained from the absorption spectra of irradiated sample shows a slight decrease as compared to the pure samples, which might occur due to the increase in size of the nanoparticles. The present investigation found that the beam irradiation is a new efficient method to enhance the optical absorption performance and photo-activity of CeO₂ nanoparticles. These properties make cerium oxide useful for applications in microelectronics and optics.

3 illus, 8 ref

006440   Pramoda K;Suresh S;Govindaraj A (New Chemistry Unit, Chemistry and Physics of Materials Unit, Internati, , Jakkur P.O., Bangalore, 560 064, Email: govind@jncasr.ac.in) : Graphene composites containing chemically bonded metal oxides. Bull Mater Sci 2013, 36(4), 585-90.

Composites of graphene involving chemically bonded nano films of metal oxides have been prepared by reacting graphene containing surface oxygen functionalities with metal halide vapours followed by exposure to water vapour. The composites have been characterized by electron microscopy, atomic force microscopy and other techniques. Magnetite particles chemically bonded to graphene dispersible in various solvents have been prepared and they exhibit fairly high magnetization.

10 illus, 17 ref

006439   Osman A M;Abdel-Monem A M;El Abd A (Faculty of Science and Arts, Physic Dep, University of Al Jouf, Post Office 207, Al-Jouf, KSA, Email: ahmed2004ge@yahoo.co.uk) : Measurement of void fraction in pipes by neutron backscattering imaging technique. Indian J pure appl Phys 2014, 52(7), 437-43.

Void fraction of air-water two phase flow has been investigated using neutron backscatter imaging technique. A series of static measurements have been carried out for pipes having different radii and wall thicknesses. The obtained thermal neutron images successfully discriminate between the pipes having different void fraction. Linear relationship describes the values of backscattered thermal neutrons obtained from the reconstructed images and void fraction with some deviations in case of pipe four when buried at 10 cm depth. The obtain results indicate the reliability and effectiveness of the technique for studying void fraction of air-water two phase flow.

10 illus, 1 table, 16 ref

006438   Nuwal A;Kakani S;Kakani S L (Physics Dep, Sangam Univ, Bhilwara-311 001, Email: slkakani28@gmail.com) : Two band model for the iron based superconductors. Indian J pure appl Phys 2014, 52(6), 411-22.

Two band model for Fe-As based oxygen containing superconductors is developed using the Green's function technique and equation of motion method. Self-consistent equations for superconducting order parameters (Δ_p,Δ_d, specific heat (C_es) and density of states are derived. The theory is applied to explain the experimental results in oxygen containing Fe-As superconductors Sm_0.95La_0.05O_0.85F_0.85Fe_0.15FeAs and SmO_1-xF_xFeAs. The comparison to experimental data is given where these are available. The agreement between theory and experiments is quite encouraging.

8 illus, 9 tables, 66 ref

006437   Nanduri P K;Guven U (NO, , ) : Performance analysis of efficient channel coding schemes for deep space and interplanetary missions. Res Rev : J Space Sci Technol 2014, 3(2), 15-21.

This paper discusses about the space communication challenges especially deep space communications with a detailed analysis on channel coding techniques and modulation schemes. It explains about the free space loss (FSL) that occurs due to the presence of long distances (in terms of Astronomical Units) in AWGN channel with relation to the power transmitted and power received. Also, it discusses different kinds of digital modulation techniques employed in tandem with the algebraic channel coding schemes. The discussion in this paper is confined to algebraic coding schemes and probabilistic coding schemes, as such, are not give a detailed look. Convolutional - hard and soft, Hamming. Golay, Reed-Solomon are compared and their noise combat ability is discussed in detail using the help of computer based simulations in MATLAB and SIMULINK. it is shown that low BERs can be achieved at very small E_b/N₀ ratios using OQPSK, MSK, and GMSK techniques. Robust coding schemes for space communications are given an overview. All the codes and modulation schemes are compared and analyzed for an A WGN channel. Also an introduction to quantum communication is discussed with reference to coding schems.

006436   Nandu Jith P J (NO, , ) : System design for high speed trajectory changing of a solar sail. Res Rev : J Space Sci Technol 2014, 3(2), 22-7.

Solar sails were created as a new form of satellite propulsion which uses the radiation pressure of the light from the stars or a laser to push ultrathin mirrors to high speeds. The new design incorporates ablative laser propulsion for trajectory changing of the probe at a desired point in space to he maneuvered towards the desired object. The design provides a combination of sail propulsion and laser propulsion systems to create the desired effect on to the path of a satellite or a probe. The solar sail will be used as a constant source of thrust during the probe's journey to the intended target and the laser propulsion system will be only activated during its final stretch of its journey for major trajectory changing and positioning of the probe on to the target.

006435   Naik R;Ganesan R (Physics Dep, Utkal University, Bhubaneswar-751 004, Email: ramakanta.naik@gmail.com) : Compositional dependence properties change in S₄₀Se_60-xSb_x alloys. Indian J pure appl Phys 2014, 52(7), 444-9.

Bulk samples of S₄₀Se_60-xSb_x (with x=10, 20, 30 and 40 at. %) were prepared from high purity chemicals by melt quenching technique. The samples compositions were confirmed by using energy dispersive analysis of X-rays. X-ray diffraction studies revealed that all the samples have poly-crystalline phase. The variation in optical properties with compositional has been investigated by X-ray photoelectron spectroscopy and Raman spectroscopy. The optical band gap of the thin films is found to be decreased with composition. Increasing Sb content was found to affect the structural and optical properties of bulk samples. The intensity of core level spectra changes with the addition of Sb clearly interprets the optical properties change due to compositional variation. The Raman shift and new peak formation in these samples clearly show the structural modifications due to Sb addition.

7 illus, 1 table, 41 ref

006434   Monteiro A P;Vijaya Kumar K B;Bhaghyesh (Physics Dep, Mangalore Univ, Mangalagangotri, Mangalore-574 199, Email: kbvijayakumar@yahoo.com) : Radiative decays of ground state light vector mesons with non-relativistic and relativistic phase spaces and other decay properties. Indian J pure appl Phys 2014, 52(6), 369-73.

Comprehensive study of some of the decay properties of ground state light vector mesons within the framework of non relativistic potential model has been made in the present paper. Some of the decay properties and radiative decay widths of light vector mesons are calculated using spectroscopic parameters. The E1 and M1 transition widths have been studied both in case of non-relativistic and relativistic phase spaces. A good agreement between the calculated and experimental data is obtained in case of relativistic phase space calculations.

3 tables, 31 ref

006433   Mishra M;Singh A P;Sambyal P;Teotia S;Dhawan S K (Conducting Polymer Group, , CSIR-National Physical Laboratory Dr K S Krishnan Road, New Delhi-110 012, Email: skdhawan@mail.nplindia.org) : Facile synthesis of phenolic resin sheets consisting expanded graphite/γ-Fe₂O₃/SiO₂ composite and its enhanced electromagnetic interference shielding properties. Indian J pure appl Phys 2014, 52(7), 478-85.

The paper reports the preparation of thin sheets of expanded graphite decorated with γ-Fe₂O₃ and SiO₂by compression molding. Different formulations have been prepared to study the effect of dielectric and magnetic constituent on the electrical, magnetic and dielectric properties of multiphase composite. One of the formulations shows unprecedented microwave shielding response with absorption dominated shielding effectiveness value of 55.40 dB which strongly depends on dielectric losses and magnetic losses. The results show that the dielectric loss of the composites can be attributed to natural resonance, electron polarization relaxation, interfacial polarization and the unique layered nanostructures etc.; whereas eddy current effect mainly causes the magnetic loss. Since observed attenuation is greater than the recommended limit (30 to 40 dB) of commercial application, therefore, these are potentially applied for absorbing mobile signal interference in daily life.

6 illus, 41 ref

006432   Knezevic;Dragovic;Ibrahimovic V;Srekovic M; Kovaevic A G (Faculty of Electrical Engineering, University of Belgrade, Serbia, Email: Aleksander.Kovacevic@ipb.ac.rs) : Numerical complexity of real-time tracking of objects in defined space by infrared optoelectronic devices. Indian J pure appl Phys 2014, 52(7), 457-64.

Remote tracking and recognition of various objects in defined space are complex multidisciplinary problems. Depending on selected scene being investigated (object size and dynamics, time needed for data processing and estimation), and on chosen optoelectronic system design, several solutions are available. For the fieldwork, the passive remote detection seems to be the most convenient. Economically reasonable approach with selected non-sophisticated modest equipment is proposed, evaluated and discussed. A numerical experiment is performed with own-developed algorithm in which unreal cases are automatically eliminated during the output vector data evaluation. Gaussian distribution method is implemented here. The average calculated times, resulted from simulation, were shorter than simulated values increased by 3 σ.

6 illus, 19 ref

006431   Islam S;Lakshmi G B V S;Zulfequar M;Husain M; Siddiqui A M (Physics Dep, Jamia Millia Islamia, New Delhi-110 025, Email: amsiddiqui@jmi.ac.in) : RF plasma polymerization and electrical, optical and structural properties of thin films of poly(o-toluidine). Indian J pure appl Phys 2014, 52(7), 486-90.

Thin films of poly(o-toluidine) (POT) have been prepared by RFplasma polymerization at radio frequency (RF) power input 15 W, making suitable modifications in a RF-sputtering set-up. The deposition rate is found to be 3.33 nm/min. The films are characterized by dcconductivity, UV-Visible, FTIR and XRD techniques. The dc conductivity of the POT thin films has been analyzed in the temperature range 312-435 K and is found to increase with temperature. The Arrhenious plot of dcconductivity shows straight line behaviour. The optical band gap has been estimated to be 1.66 eV from UV-visible absorption spectrum. From FTIR, the formation of POT has been confirmed. It is found that the synthesized polymer is cross-linked. Thickness of the polymer films has been measured to be 200 nm by ellipsometry. XRD shows the amorphous nature of the prepared films.

6 illus, 31 ref

006430   Giribabu L;Kanaparthi R K (Inorganic and Physical Chemistry Div, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 607, Email: giribabu@iict.res.in) : Are porphyrins an alternative to ruthenium(II) sensitizers for dye-sensitized solar cells?. Curr Sci 2013, 104(7), 847-55.

This review article reports recent advances in porphy rin-based sensitizers or dye-sensitized solar cell (DSSC) applications. The sensitizer is known to be one of the key components of the DSSC device, which plays a vital role in achieving high efficiency and durability. So far, ruthenium(II) polypyridyl complexes have been extensively used as sensitizers achieving more than 11% efficiency. The major technical disadvantages with these complexes are expensive due to rarity of the metal, tedious purification process and lack of absorption in the red region of the visible spectrum, where the light harvesting process is maximum. For this reason, porphyrins are found to be robable alternative sensitizers based on their thermal, electronic and photochemical properties. A great variety of porphyrins have been used as sensitizers in DSSC applications for the last three decades and recently, the efficiency of porphyrin-based sensitizers has crossed 12%.

4 illus, 65 ref

006429   Gadani D H;Vyas A D;Rana V A (Physics Dep, C U Shah Science College, Ashram Road, Ahmedabad, Email: dhgadani@yahoo.com) : Dielectric properties of wet and fertilized soils at radio frequencies. Indian J pure appl Phys 2014, 52(6), 399-410.

Dielectric constant ∈ and dielectric loss ∈ of moist soil and fertilized soil have been measured in the frequency range 10 kHz-2 MHz using a precision LCR meter. The values of ∈ and ∈ of the wet (Gandhinagar district sandy loam) soil are found to decrease with increase in frequency from 10 kHz to 2 MHz. The value of tan δ is found to increase with increase in moisture content in the soil. The peak of tandδ is found to shift towards lower frequency side as the moisture content in the soil increases. The conductivity spectra of soil show the increase in conductivity σ = σ + j∈" with increase in moisture content in the soil. The value of σ increases slowly with increase in frequency for wet soil. A dip is observed in the value of σ" spectra at electrode polarization frequency, which is also observed in complex impedance plane plot of the wet soils. To see the effect of fertilizer on the soil two fertilizers are selected, sulphet of potash (SOP) and zinc chelate. It has been observed that ∈' and ∈" of the wet fertilized soils decrease with increase in frequency from 10 kHz to 2 MHz. Further, the values of ∈' and ∈" increase with increase in % concentration of fertilizer in the wet soil. The variation of tan δ and conductivity with frequency and fertilizer in the soils has also been studied.

14 illus, 1 table, 18 ref

006428   Das S;Lalla N P;Okram G S (Applied Physics Dep, Indian School of Mines, Dhanbad-826 004, Email: sourav.das1988@gmail.com) : Synthesis, characterization and dielectric properties of nanocrystalline nickel. Indian J pure appl Phys 2014, 52(6), 386-90.

Nickel nanoparticles were synthesized by thermal decomposition route. It was characterized by XRD, TEM and FTIR spectroscopy. Dielectric properties and ac electrical conductivity were measured by impedance spectroscopy. The particle sizes calculated from XRD and TEM measurement were about 1.22 and 10 nm, respectively. FTIR spectra showed the presence of organic elements. The variation of dielectric constant, dielectric loss and ac electrical conductivity with frequency and temperature, has been studied.

9 illus, 18 ref

006427   Chari V D;Sharma D V S G K;Prasad P S R; Ramana Murthy S (Gas Hydrates group, National Geophysical Research Institute (Council for Scientific & Indu, Hyderabad-500 007, Email: dhanu_jay2000@yahoo.com) : Dependence of thermal conductivity in micro to nano silica. Bull Mater Sci 2013, 36(4), 517-20.

This work presents the measurement of thermal conductivity of nano-silica particles using needle probe method. The validation test of thermal probe was conducted on ice and THF hydrates using our experimental set up and the results are satisfactory when compared with the literature data. The nano silica used in this study is with particle sizes in the range 50-1000 nm. The sand powders sieved in different sizes <60>75 and 75μm <62> d <62>250μm were also studied to probe the particle size dependence on thermal conductivity. Thermal conductivity decreased by about 70% in silica nano powders.

7 illus, 1 table, 11 ref

006426   Arya S;Khan S;Suresh Kumar;Verma R;Lehana P (Physics & Electronics Dep, University of Jammu, Jammu-180 006, Email: pklehanajournals@gmail.com) : Synthesis of copper telluride nanowires using template-based electrodeposition method as chemical sensor. Bull Mater Sci 2013, 36(4), 535-9.

Copper telluride (CuTe) nanowires were synthesized electrochemically from aqueous acidic solution of copper (II) sulphate (CuSO₄.5H₂O) and tellurium oxide (TeO₂) on a copper substrate by template-assisted electrodeposition method. The electrodeposition was conducted at 30 °C and the length of nanowires was controlled by adjusting deposition time. Structural characteristics were examined using X-ray diffraction and scanning electron microscope which confirm the formation of CuTe nanowires. Investigation for chemical sensing was carried out using air and chloroform, acetone, ethanol, glycerol, distilled water as liquids having dielectric constants 1, 4.81, 8.93, 21, 24.55, 42.5 and 80.1, respectively. The results unequivocally prove that copper telluride nanowires can be fabricated as chemical sensors with enhanced sensitivity and reliability.

7 illus, 2 tables, 21 ref

006425   Afruz F B;Tafreshi M J (Faculty of Physics, Semnan Univ, Semnan, Iran, Email: mj.tafreshi@gmail.com) : Synthesis of γ-Al₂O₃ nano particles by different combustionmodes using ammonium carbonate. Indian J pure appl Phys 2014, 52(6), 378-85.

Gamma-alumina nanoparticles have been successfully synthesized by different modes of combustion using ammonium carbonate as well as effective material. Thermodynamic calculations predicted the capability of ammonium carbonate as compared with some other fuels in production of nanoparticles with improved properties by combustion process. The proposed reactions involved in synthesizing process were verified by TG analysis. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N₂ adsorption (BET), Transmission electron microscopy (TEM) and Dynamic light scattering (DLS). For all modes of combustion, γ-alumina nanoparticles were obtained with crystallite size in the range 2.0-2.5 nm. But DLS and BET analyses showed that conventional volume combustion synthesis mode is advantageous over other modes, with respect to the higher specific surface area and narrower agglomerate size distribution of the products. Specific surface area for synthesized samples was found to be in the range 328.0-392.8 m^{2.g-1. Ammonium carbonate was found to be a suitable material for the production of alumina fine particles with high specific surface area.}

2 tables, 24 ref

006424   Acharya S;Sharma R (Physics Dep, Himachal Pradesh Univ, Shimla-171 005, Email: sramanb@mailcity.com) : Plasmon characteristics in stage-1 graphene intercalation compounds. Indian J pure appl Phys 2014, 52(6), 374-7.

Plasmon characteristics in stage-1 graphene intercalation compounds (GIC's) using the massless Dirac fermion (MDF) gas approximation have been reported. The superlattice model of GIC's with negligible c-axis conductivity has been considered. With the discussion of the weak and the strong c-axis coupling at graphene-intercalant hetrojunction plasmon characteristics of GIC's are predicted. A reasonable agreement has been found between our results and the experimental results of Ritsko and Rice.

4 illus, 12 ref

005356   Yang H;shan X;Zhou C;Zhou Q;Li W;Cheng J (School of Materials Science and Engineering, Guilin Univ of Electronic Technology, Guilin, Guangxi 541004, People's Republic of China, Email: yhb_letters@163.com) : Microstructure, dielectric and piezoelectric properties of lead-free Bi_0.5Na_0.5TiO₃-Bi_0.5K_0.5T iO₃-BiMnO₃ ceramics. Bull Mater Sci 2013, 36(2), 265-70.

To improve the piezoelectric properties of Bi_0.5Na_0.5TiO₃-based ceramics, a new perovskite-type lead-free piezoelectric (1 -x -y)OBi_0.5Na_0.5TiO₃-xBi_0.5K_0.5TiO₃- yBiMnO₃ system has been fabricated by a conventional solid-state reaction method and their microstructure, dielectric and piezoelectric properties have been investigated. The results of X-ray diffraction (XRD) analysis reveal that the addition of small amounts of BiMnO₃ did not cause a remarkable change in crystal structure, but resulted in an evident evolution in microstructure. An obvious secondary phase was observed in samples with high Bi_0.5K_0.5TiO₃ content. It is found from dielectric constant curves that low-temperature hump disappeared with increasing y and it appeared again with increasing x. The piezoelectric properties significantly increase with increasing Bi_0.5K_0.5TiO₃ and BiMnO₃ content. The piezoelectric constant and electromechanical coupling factor attain maximum values of d₃₃ = 182 pC/N at x = 0.21(y = 0.01) and k_p = 0.333 at x = 0.18 (y = 0.01), respectively.

4 illus, 1 table, 35 ref

005355   Singh R P;Gupta R S;Singh A (Physics Dep, Govt Tilak Collage, Katni, Madhya Pradesh, Email: rukmani.physics@gmail.com) : Effect of solar influence on geomagnetosphere. Ultra Scient phys Sci-Sect B 2013, 25(3), 383-8.

An inter-comparison of the correlative analysis, we have taken daily value and yearly mean value of total interplanetary magnetic field B, solar wind speed (V), plasma electric field (V.B), sunspot number (Rz), geomagnetic index (Ap) and number of geomagnetic event (Ap ≥ 50 nT), for the solar cycle 22 to ascending phase of recent solar cycle 24, (Years 1986 - October 2013), 23 8 number of geomagnetic event are identified and a correlative study has been preformed. It has been found that the positively correlated between total interplanetary magnetic field (B), solar wind velocity (V), plasma electric field (V.B) with geomagnetic index (AP ≥ 50). We found that the plasma electric field (V.B) is the most effective parameter for producing larger geomagnetic disturbances.

2 illus, 19 ref

005354   Singh A K (Physics Dep, Bareilly College, Bareilly-243 005, Email: aksnmr@gmail.com) : Dielectric relaxation and dipole moment of some binary mixtures using microwave absorption data. Ultra Scient phys Sci-Sect B 2013, 25(3), 351-8.

The dipole moment and dielectric relaxation time of different concentration binary mixtures of 1-propanol and alkyl benzoates (Methyl Benzoate and Ethyl Benzoate) have been measured at microwave frequency 9.132 GHz at different temperatures. Thermo dynamical parameters like molar free energy of activation (ΔF_ε), molar enthalpy of activation (AHS) and molar entropy of activation (ΔS_ε) have been evaluated by considering the relaxation as the rate process.

4 illus, 5 tables, 20 ref

005353   Rawal S K;Chawla A K;Jayaganthan R;Chandra R (Nano Science Laboratory, Institute Instrumentation Centre, Indian Institute of Technology Roork, Roorkee-247 667) : Effect of power variation on wettability and optical properties of co-sputtered titanium and zirconium oxynitride films. Bull Mater Sci 2013, 36(3), 403-9.

The present paper deals with deposition of titanium and zirconium oxynitride films prepared from co-sputtering titanium and zirconium targets by reactive RF magnetron sputtering. The effect of power variation on various properties of the deposited films is analysed. The film gets transformed from amorphous to well crystalline oxynitride films with gradual increase of target powers as observed from XRD graphs. The films exhibit hydrophilic and hydrophobic behaviours depending upon the presence of various phases. Surface energy decreases as the film properties change from hydrophilic to hydrophobic due to greater contact angle values. The optical properties were measured by UV-Vis-NIR spectrophotometer, transmission spectra and bandgap values show variation with respect to change in elemental composition as determined from EDS analysis.

6 illus, 2 tables, 45 ref

005352   Rajeswari N;Selvaskarapandian S;Prabu M; Karthikeyan S;Sanjeeviraja C (Physics Dep, Kalasalingam Univ, Krishnankoil-626 126, Email: sekarapandian@rediffmail.com) : Lithium ion conducting soid polymer blend electrolyte based on bio-degradable polymers. Bull Mater Sci 2013, 36(2), 333-9.

Lithium ion conducting polymer blend electrolyte films based on poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) with different Mwt% of lithium nitrate (LiNO_3g values of 70 PVA-30 PVP blend and 70 PVA-30 PVP with different Mwt% of LiNO₃ electrolytes shown by DSC thermograms indicate an interaction between the polymer and the salt. The dependence of T_g and conductivity upon salt concentration has been discussed. The ion conductivity of the prepared polymer electrolyte has been found by a.c. impedance spectroscopic analysis. The PVA-PVP blend system with a composition of 70 wt% PVA: 30 wt% PVP exhibits the highest conductivity of 1 58 x 10^{-6 Scm-1 at room temperature. Polymer samples of 70 wt% PVA-30 wt% PVP blend with different molecular weight percentage of lithium nitrate with DMSO as solvent have been prepared and studied. High conductivity of 6 828 x 10-4 Scm-1 has been observed for the composition of 70 PVA:30 PVP:25 Mwt% of LiNO₃ with low activation energy 0.2673 eV. The conductivity is found to increase with increase in temperature. The temperature dependent conductivity of the polymer electrolyte follows the Arrhenius relationship which shows hopping of ions in the polymer matrix. The relaxation parameters (ω) and (τ) of the complexes have been calculated by using loss tangent spectra. The mechanical properties of polymer blend electrolyte such as tensile strength, elongation and degree of swelling have been measured and the results are presented.}

11 illus, 3 tables, 18 ref

005351   Paikray P;Dash S K (Physics Dep, KPAN College, Bankoi, Khurda (Odisha)) : Heat and mass transfer in the unsteady couette flow of oldroyd liquid between two horizontal parallel porous plates with heat sources, chemical reaction and soret effect when the lower plate moves with time varying velocity. Ultra Scient phys Sci-Sect B 2013, 25(3), 369-82.

The effects of heat transfer in the unsteady Couette flowof Oldroyd liquid between two horizontal parallel porous plates with heat sources have been studied when the lower plate suddenly starts moving with time varying velocity A t^{'n. The non-dimensional constitutive equation of the flow have been solved for velocity and temperature using Galerkin technique. Then, skin-friction and the rates of heat transfer have been derived. The flow behaviour has been studied through graphs and tables. It is observed that the velocity of flow decreases as elastic parameter increases, but the reverse effect is marked with permeability parameter.}

10 illus, 2 tables, 16 ref

005350   Mouhammad S A;Amer A F (Physics Dep, Taif Univ, Saudi Arabia, Email: saifnet70@hotmail.com) : Physical model of the interphase boundary of the passivating layer on the metal in the electrolyte solutions. Oriental J Chem 2014, 30(2), 661-5.

The model of processes on the interphase boundary metal- passivating layer is proposed. The balance of ions upon the formation of the cells of oxide is examined. The velocity expressions of these processes are obtained.

2 ref

005349   Mondal S;Bhattacharyya S R;Mitra P (Physics Dep, Burdwan Univ, Golapbag, Burdwan-713 104, Email: mitrapartha1@rediffmail.com) : Preparation of manganse-doped ZnO thin films and their characterization. Bull Mater Sci 2013, 36(2), 223-9.

In this study, pure and manganese-doped zinc oxide (Mn:ZnO) thin films were deposited on quartz substrate following successive ion layer adsorption and reaction (SILAR) technique. The film growth rate was found to increase linearly with number of dipping cycle. Characterization techniques of XRD, SEM with EDX and UV-visible spectra measurement were done to investigate the effect of Mn doping on the structural and optical properties of Mn:ZnO thin films. Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing manganese incorporation. Particle size evaluated using X-ray line broadening analysis shows decreasing trend with increasing manganese impurification. The average particle size for pure ZnO is 29.71 nm and it reduces to 23.76 nm for 5% Mn-doped ZnO. The strong preferred c-axis orientation is lost due to manganese (Mn) doping. The degree of polycrystallinity increases and the average microstrain in the films decreases with increasing Mn incorporation. Incorporation of Mn was confirmed from elemental analysis using EDX. As the Mn doping concentration increases the optical bandgap of the films decreases for the range of Mn doping reported here. The value of fundamental absorption edge is 3.22 eV for pure ZnO and it decreases to 3.06 eV for 5% Mn:Zno.

10 illus, 29 ref

005348   Lateef Taofeeka;Ayodele Folasade G (Physics Dep, Ekiti State Univ, Ado-Ekiti, Ekiti State (Nigeria), Email: lattaof@yahoo.com) : Nigeria local clay as an alternative for imported bentonite as drilling mud in oil sector. Ultra Scient phys Sci-Sect B 2013, 25(3), 389-95.

Drilling mud is an important element of the drilling processes. Any drilling mud must possess common properties that facilitate safe and satisfactory completion of the well. However, the importation of bentonite is very expensive and the consumption is very high, there is need to further the research on the use of local clay as drilling mud. Clay samples were collected from three locations in Ekit-State, Nigeria. Atterberg limit (plastic, liquid and shrinkage limit) and pH of the samples were determined using laboratory approach and compared with the API standard. The liquid limit of the clay samples range between 28.0% and 50%, while the plastic limit range between 19.2% and 22.8% and the plasticity index ranges between 8.8% and 27.5%. The pH value of the clay samples range between 5.5 and 6.0. It decreases after addition of both Na₂CO₃ and KOH, ranges between 4.0 and 4.5. The pH value before and after enhancement did not meet the API specification for acceptable drilling mud of 9.0. However, the clay samples from Papa and Isan-Ekiti which consist of montmorillonite minerals can be used as bentonite if its pH is enhanced.

4 tables, 9 ref

005347   Khairnar A J;Mahajan A M (Electronics Dep, North Maharashtra Univ, Jalgaon-425 001, Email: ammahajan@nmu.ac.in) : Sol-gel deposited ceria thin films as gate dielectric for CMOS technology. Bull Mater Sci 2013, 36(2), 259-63.

In this work, cerium oxide thin films were prepared using cerium chloride heptahydrate, ethanol and citric acid as an additive by sol-gel spin-coating technique and further characterized to study the various properties. Chemical composition of deposited films has been analysed by FTIR which shows existence of CeCO₂. The samples have been optically characterized using ellipsometry to find refractive index of 2.18 and physical thickness which is measured to be 5.56 nm. MOS capacitors were fabricated by depositing aluminum (Al) metal using the thermal evaporation technique on the top of CeO₂ thin films. Capacitance-voltage measurement was carried out to calculate the dielectric constant, flat-band voltage shift of 18.92, 0.3-0-5 V, respectively and conductance-voltage study was carried out to determine the D_it of 1.40 x 10^{13 eV-1 cm-2 at 1 MHz.}

6 illus, 25 ref

005346   Hanumantharao R;Kalainathan S (NO, Vignan's Institute of Information Technology, Physics Division, Visakhapatnam-530 049, Email: kalainathan@yahoo.com) : Microhardness studies on nonlinear optical L-alanine single crystals. Bull Mater Sci 2013, 36(3), 471-4.

Vickers and Knoop microhardness tests were carried out on grown L-alanine single crystals by slow evaporation technique over a load range of 10-50 g on selected broad (2 0 3) plane. Vickers (H_v) and Knoop (H_k) microhardness for the above loads were found to be in the range of 60-71 kg/mm^{2 and 35-47 kg/mm2, respectively. Vickers microhardness number (H_v) and Knoop microhardness number (H_k) were found to increase with increasing load. Meyer's index number (n) calculated from H_v shows that the material belongs to the soft material category. Using Wooster's empirical relation, the elastic stiffness constant (c₁₁) was calculated from Vickers hardness values. Young's modulus was calculated using Knoop hardness values. Hardness anisotropy has been observed in accordance with the orientation of the crystal.}

6 illus, 1 table, 17 ref

005345   Etefagh R;Shahtahmasebi N;Karimipour M (NO, Payame Nour Univ, Mashhad, Iran, Email: m.karimipour@vru.ac.ir) : Effect of Zn doping on optical properties and photoconductivity of SnS₂ nanocrystalline thin films. Bull Mater Sci 2013, 36(3), 411-16.

Zn-doped SnS₂ thin films have been deposited simply by spray pyrolysis technique. The doping level was changed from [Zn/Sn] = 0 to 7.5 at%. The films were characterized by means of X-ray diffraction, scanning tunneling microscopy (STM), energy dispersive X-ray analysis (EDX), photoluminescence and UV-Vis spectroscopy. XRD patterns of the films with different zinc contents show that all samples have polycrystalline structure with Berndtite dominant phase and preferred orientation of (001) growth plane. Zn insertion causes a significant decrease in grain size. Optical bandgap of the films have been calculated for different dopant concentrations and they lie in the region of 2.3-2.7 eV. Surprisingly, regardless of doping level, the luminescent properties of films are related to the fundamental bandgap energy and deep levels inside the bandgap. Photoconductivity of the films have been measured under visible light. Sensitivity to the light increases by zinc incorporation, which was a large amount for SnS₂:Zn of 7.5%.

7 illus, 23 ref

005344   Boukredimi D;Allouche H (Laboratoire de Physique des Couches Minces et Materiaux pour l'Electro, Departementde Physique, Faculte des Sciences, Universite d'Oran, Es-senia 31100, Oran, Algerie) : Accurate quasi static capacitance for abrupt homojunction under forward and reverse polarization. Bull Mater Sci 2013, 36(2), 251-8.

Presents a new approach to derive the capacitance-voltage characteristic for an abrupt homojunction with uniform doping (N_A in p-region and ND in n-region) under forward and reverse polarization. Under thermal equilibrium conditions, we show that it is possible to obtain analytically the exact capacitance-voltage characteristic without any simulation for the symmetric case (N_A = N_D). Also propose a model of the total capacitance under forward and reverse polarization for the asymmetric case (N_A ≠ N_D).

6 illus, 27 ref

005343   Aliaj F;Syla N;Avdiaj S;Dilo T (Physics Dep, Faculty of Mathematical and Natural Sciences, Prishtina Univ, Rr. Nena Tereze nr. 5, 10000 Prishtina, Kosovo, Email: fisnik.aliaj@uni-pr.edu ) : Effect of bias voltage on microstructure and mechanical properties of arc evaporated (Ti, Al)N hard coatings. Bull Mater Sci 2013, 36(3), 429-35.

In the present study, authors report on the effect that substrate bias voltage has on the microstructure and mechanical properties of (Ti, A1)N hard coatings deposited with cathodic arc evaporation (CAE) technique. The coatings were deposited from a Ti_0.5Al_0.5 powder metallurgical target in a reactive nitrogen atmosphere at three different bias voltages: U_B = -25, -50 and -100 V. The coatings were characterized in terms of compositional, microstructural and mechanical properties. Microstructure of the coatings was investigated with the aid of X-ray diffraction in glancing angle mode, which revealed information on phase composition, crystallite size, stress-free lattice parameter and residual stress. Mechanical properties were deduced from nano-indentation measurements. The residual stress in all the coatings was compressive and increased with increasing bias voltage in a manner similar to that reported in literature for Ti-Al-N coatings deposited with CAE. The bias voltage was also found to significantly influence the phase composition and crystallite size. At -25 V bias voltage the coating was found in single phase fcc-(Ti, A1)N and with relatively large crystallites of <126>9 nm. At higher bias voltages (-50 and -100 V), the coatings were found in dual phase fcc-(Ti, AI)N and fcc-AIN and the size of crystallites reduced to approximately 5 nm. The reduction of crystallite size and the increase of compressive residual stress with increasing bias voltage both contributed to an increase in hardness of the coatings.

5 illus, 1 table, 24 ref

005342   Agrawal P;Parmar P (Electronics and Computer Maintenance Dep, St. Aloysius College (Autonomous), Jabalpur-482 001, Email: dr_p_agrawal@hotmail.com) : Study of temperature dependent electrical conductivity and dielectric properties of PPY/SWCNT/PVA composites. Ultra Scient phys Sci-Sect B 2013, 25(3), 396-402.

The effect of temperature on the DC and AC electrical conductivities of pure PPy and PPy/SWCNT as well as PPy/S WCNT/PVA composites has been discussed in this paper. The activation energies for these materials have been calculated using Arrhenius equation. The values of activation energies for pure PPy, PPy/SWCNT and PPy/S WCNT/PVA are found to be 1.83 eV, 3.166 eV and 6.6 eV, respectively. The increment of conductivity with temperature has been explained on the basis of reduction of energy band gap and hopping of charge carriers. PPy, PPy/SWCNT and PPy/SWCNT/PVA are found to exhibit larger dielectric constants than pure PVA. The enhanced dielectric constant of the composites has been correlated with the increase of molecular ordering due to addition of carbon nanotubes.

3 illus, 1 table, 33 ref

004312   Premlata Kumari;Dutta A;Prasad S;Sinha T P (Chemistry Dep, Government P.G. College Lansdowne, Pauri-Garhwal-246 139) : Dielectric relaxation of double perovskite Ba₂LaSbO₆. Sci Cult 2014, 80(3-4), 98-102.

Ba₂LaSbO₆ (BLS) ceramic is synthesized by the solid-state reaction technique. The Raman_ spectrum at room temperature suggests the rhombohedral R3 space group of the material. The frequency-dependent dielectric properties of the sample are investigated in the temperature range from 30 °C to 300 °C. The Cole-Cole model is used to study the dielectric relaxation of the sample. The dielectric relaxation frequencies at different temperatures are found to obey the Arrhenius law with activation energy of 0.48 eV. Impedance formalism is used to study the relaxation mechanism in BLS. The frequency, dependent conductivity spectra follow the power law.

5 illus, 2 tables, 12 ref

004311   Monowe P;Sebitla L (Physics Dep, Botswana Univ, Gaborone, Botswana, Email: monowep@mopipi.ub.bw) : Volume variation of static dielectric constant and optic mode gruneisen parameters of caesium and thallium halides. Int J mathl Sci 2014, 13(1-2), 139-47.

It is Investigated the dielectric behavior of crystals having caesium chloride structure using a modified Born-Mayer model for interionic force. In particular theoretical estimates of static polarizability, volume derivatives of static polarizability, static dielectric constant and optic mode Gruneisen parameters for caesium and thallium halides have been made. Our results show that they are in close agreement with their corresponding experimental values. Finally we discuss the various factors which lead to the success of our analysis over the usual Born model analysis.

3 tables, 15 ref

004310   Malathi M;Tamilarasan K (Physics Dep, Kongu Engineering College, Perundurai-638 052, Email: mal_kongu@yahoo.com) : Synthesis and characterization of polyethylene oxide based nano composite electrolyte. Sadhana 2014, 39(4), 999-1007.

Polyethylene oxide (PEO) - montmorillonite (MMT) composite electrolytes were synthesised by solution casting technique. The salt used for the study is Lithium perchlorate (LiClO4). The morphology and percentage of crystallinity data were obtained through X-ray Diffraction and Differential Scanning Calorieme-try. The ionic conductivity of the polymer electrolytes was studied by impedance spectroscopy. The addition of MMT resulted in an increase in conductivity over the temperature range of 25-60°C. The ionic conductivity of a composite polymer electrolyte containing 1.2 wt% MMT was 1 x 10^{-5 S cm-1 at 25°C, which is at least one order of magnitude higher than that of the polymer electrolyte (4 x 10-7 S cm-1). The increase in ionic conductivity is explained on the basis of crystallinity of the polymer electrolyte.}

8 illus, 3 tables, 15 ref

004309   Gurav S S;Salvi S V (Physics Dep, K. E. S. Anandibgai Pradhan Science College, Nagothane-402 106, Email: sandeeshsgurav@gmail.com) : Effect of temperature and phase on properties of metal pseudobrookite. Int J chem Sci,Udaipur 2013, 11(1), 341-9.

Iron titanate is a metal pseudobrookite, which exhibits many interesting properties such as spin glass behaviour, thermal microcracking, magnetic texture and high resistivity. The polycrystalline pseudobrookite has wide range of applications. This communication presents the comparative study of electrical resistivity and dielectric properties as a function of temperature and relaxation spectra of pure iron titanates prepared by using rutile form of titanium oxide and sintered at two temperatures viz. 1000°C and 1250°C and also prepared at 1250°C using anatase form of titanium oxide. The iron titanates are synthesized by usual standard ceramic technique using A.R. grade oxides. The single phase formation is confirmed by XRD and FTIR techniques. Structurally all the samples remain as pseudobrookite having orthorhombic unit cell. The analysis of the relaxation spectra establishes the presence of space-charge, which increases with the sintering temperature for the pseudobrookite prepared from rutile TiO2. Also the analysis shows that the pseudobrookite prepared from anatase TiO₂ has lower dielectric and electric properties at low frequency (1 kHz) and shows pronounced hysteresis indicating lower microcrack healing. The changes in the resistivity, dielectric constant and dielectric loss are discussed and analysed on the basis of structural changes.

7 illus, 3 tables, 14 ref

004308   El-Agmy R M;Al-Hosiny N (Physics Dep, Taif Univ, PO Box 888, Taif, Saudi Arabia, Email: redaagmy@yahoo.com) : Improvement of laser beam quality by compensating thermally induced lens in - solid-state lasers. Int J chem Sci,Udaipur 2013, 11(2), 786-96.

Numerical simulations for compensation of thermally induced lens in diode pumped Nd : YLF laser rod are presented. We have proposed a design for intra-cavity compensation of thermally induced lens for π-polarization. The numerical calculations showed that the Nd : YLF laser rod can be pumped up to 850 W before rod fractured. Temperature and stress distributions around pumped are in the Nd : YLF laser rod are also presented.

7 illus, 2 tables, 30 ref

004307   Dev A N;Das G C;Sarma J (Science and Humanities Dep, College of Science and Technology, RUB, Bhutan) : Shock wave phenomena in unmagnetized dusty plasmas. Int J mathl Sci 2014, 13(1-2), 41-51.

The nonlinear propagation of dust acoustic wave (DAW) and dust acoustic shock wave (DASW) in unmagnetized warm dusty plasmas system consisting of Maxwellian electrons and ions with the effect of dust charged fluctuation are studied using the reductive perturbation technique. Nonlinear waves (solitary and shock waves) have been observed in case of negative and positive charged dust grains from the stationary solution of the Korteweg-de Veries (KdV) equation and Burgers equation. We observed the effect of without viscosity and with viscosity term is in the derivation of Burgers equation. The fundamental properties of such nonlinear waves have been theoretically analyzed.

4 illus, 29 ref

004306   Datta P K (Physics Dep, Presidency College, Kolkata-73, Email: dattapradip@rediffmail.com) : 325 years of Newton's principia. Sci Cult 2014, 80(3-4), 72-5.

Newton's Principia Mathematica was published 325 years ago. The Principia provided a physical and mathematical basis for how basic elements of the universe work and how celestial bodies move and interact with each other and laid the foundation of modern science. In this article we have discussed briefly the contents of the Principia, its publication and the socio-economic background of Newton's emergence. It has been discussed that the social necessity at that time was responsible for Newton's emergence and the Principia.

5 ref

003232   Yildiz G;Yildiz Y G;Nezir S (Physics Dep, Science and Arts Faculty of Kirikkale Univ, 71450 Yahsihan, Kirikkale, Turkey, Email: gkcndikici@hotmail.com) : New observations on formation of thermally induced martensite in Fe-30% Ni-1% Pd alloy. Bull Mater Sci 2013, 36(1), 93-7.

Kinetical, morphological, crystallographical and thermal characteristics of thermally induced marten-site in an Fe-30%Ni-l%Pd alloy has been studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction method. Kinetics of transformation was found to be as athermal. SEM and TEM observations and X-ray method revealed α' (bcc) martensite formation in the austenite phase of alloy by thermal effect. The crystallographic orientation relationship between austenite and α' (bcc) martensite was found to be having Kurdjumov-Sachs (K-S) type relationship. In addition, the lattice parameters of austenite and martensite phases were calculated from X-ray diffraction patterns.

6 illus, 1 table, 29 ref

003231   Varughese G;Kumar A S;Philip J;Louis G (Physics Dep, Catholicate College, Pathanamthitta-689 648, Email: gvushakoppara@yahoo.co.in) : Anisotropy in elastic properties of lithium sodium sulphate hexahydrate single crystal-an ultrasonic study. Bull Mater Sci 2013, 36(1), 143-8.

The double sulfate family of (ABSO4) where A and B are alkali metal cations, is the object of great interest owing to the complexity and richness of its sequence of phase transition induced by temperature variation. A new sulfate salt characterized by the presence of water molecule in the unit cell with the chemical formula, Li₂Na₃(SO₄)2.6H₂O (LSSW), was obtained. The ultrasonic velocity measurement was done with pulse echo overlap technique [PEO]. All the six second order elastic stiffness constants, C₁₁ = C₂₂, C₃₃, C₄₄ = C₅₅, C₁₂, C₁₄ and C13 = C₂₃, are reported for the first time. The anisotropy in the elastic properties of the crystal are well explained by the pictorial representation of the surface plots of phase velocity, slowness, Young's modulus and linear compressibility in a-b and a-c planes.

7 illus, 2 tables, 12 ref

003230   Singhal S;Jauhar S;Chandra K;Bansal S (Chemistry Dep, Panjab Univ, Chandigarh-160 014, Email: sonal1174@gmail.com) : Spin canting phenomenon in cadmium doped cobalt ferrites, CoCd_xFe_2-xO₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), synthesized using sol-gel auto combustion method. Bull Mater Sci 2013, 36(1), 107-14.

Synthesis of non-collinear (spin canted) ferrites having the formula, CoCd_xFe_2-xO₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), has been carried out using the sol-gel auto combustion method. The ferrite samples show an interesting magnetic transition from Neel to Yafet-Kittel configuration, as the Cd^{2+ concentration is increased beyond x = 0.4. The FT-IR spectra confirm the formation of the metal oxide bond as they exhibit two frequency bands in the range of <126>595 cm-1 and <126>450 cm-1, corresponding to the tetrahedral and the octahedral stretching vibrations of the metal oxide, respectively. The structural evolutions of the nanophase investigated using powder X-ray diffraction (XRD) technique show that the average crystallite size is <126>35 nm. The magnetic studies reveal that the saturation magnetization, M_s, increases up to x = 0.4 and decreases when the value of x is <62>0.4. It is proposed that the incorporation of Cd2+ ion takes place into the tetrahedral sites and up to x = 0.4, Neel's model is followed. But for x <62> 0.4, canting of spins occurs, as explained by Yafet-Kittel (Y-K) model. The d.c. resistivity decreases as a function of temperature, indicating semiconducting nature of the ferrites and the positive value of Seebeck coefficient establishes p-type conduction behaviour for all the ferrite samples.}

8 illus, 2 tables, 28 ref

003229   Sarmah S;Kumar A (Physics Dep, Tezpur Univ, Tezpur-784 028, Email: ask@tezu.ernet.in) : Electrical and optical studies in polyaniline nanofibre-SnO₂ nanocomposites. Bull Mater Sci 2013, 36(1), 31-6.

Polyaniline nanoflbre-tin oxide (PAni-SnO2) nanocomposites are synthesized and mixed with polyvinyl alcohol (PVA) as stabilizer to cast free-standing films. Composite films are characterized by X-ray diffraction studies (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence spec-troscopy (PL) and UV-visible spectroscopy. XRD confirms the formation of PAni nanofibre-SnO₂ nanocomposite. From TEM images, diameter of the polyaniline nanofibre and SnO₂ nanoparticles in the PAni-SnO₂ nanocomposite are found to be 20-60 nm. SEM results show fibrous morphology of the PAni nanofibre and spherical morphology of polyaniline-SnO2 composites. The nanocomposites exhibit high relative photoluminescence intensity in violet as well as green-yellow region of visible spectrum. From electrical conductivity measurement, it is confirmed that PAni nanofibre-SnO₂ nanocomposite follows Mott's one-dimensional variable range hopping (VRH) model.

6 illus, 30 ref

003228   Priyanka;Jha A K (Applied Scciences Dep, Ambedkar Institute of Technology (CGSIPU), Geeta Colony, Delhi-110 092, Email: prof.akjha@gmail.com) : Electrical characterization of zirconium substituted barium titanate using complex impedance spectroscopy. Bull Mater Sci 2013, 36(1), 135-41.

Reports complex impedance analysis of polycrystalline complex perovskite structured BaZro_0.025Tio_0.975O₃ prepared by solid state reaction method. XRD analysis reveals the formation of single phase perovskite structure. SEM has been used to investigate grain morphology of the material. Impedance plots have been used as a tool to analyse electrical properties of the sample as a function of frequency and temperature. Bulk resistance is observed to decrease with an increase in temperature showing a typical negative temperature coefficient of resistance (NTCR) type behaviour. Nyquist (Cole-Cole) plots show both inter and intra grain boundary effects. Relaxation time is found to decrease with increasing temperature and it obeys the Arrhenius relationship. The variation of d.c. and a.c. conductivity as a function of temperature is also reported.

11 illus, 1 table, 29 ref

003227   Pal A;Khare P K (Post Graduate Studies Dep, Research in Physics and Electronics, Rani Durgawati Univ, Jabalpur-482 001, Email: alkeshpal@gmail.com) : Polarization and relaxation phenomena of polyblend films of poly(vinyl chloride) and poly(methyl methacrylate). Bull Mater Sci 2013, 36(1), 115-20.

Thermally stimulated discharge current (TSDC) studies were carried out on pure poly(methyl methacry-late), poly(vinyl chloride) and polyblends (of various weight ratios, 100:0, 90:10, 80:20 and 70:30) as a function of polarizing fields at constant temperature, to study the polarization and relaxation phenomena in them. For PVC and different blends a peak around 140-180 °C and for PMMA two peaks at around 95 and 165 °C were observed. No regular variation in peak position for PMMA and blends was observed. The various TSDC parameters i.e. activation energy, charge released and relaxation times were calculated. In the blend samples it is suggested that the chains are so entangled that in the total polarization the dipolar contribution is less and the observed polarization seems to be mainly due to the formation of induced dipoles and an increase in free volume and mobility of charge carriers due to a plasticization effect.

4 illus, 1 table, 20 ref

003226   Lemine O M;Bououdina M;Hlil E K;Al-Saie A; Jaafar A;Alyamani A;Ouladdiaf B (Physics Dep, College of Science, Al-Imam Mohammad Inb Saud Islamic Univ, (IMSIU), Riyadh, Saudi Arabia, Email: leminej@yahoo.com) : Discrepancy of room temperature ferromagnetism in Mo-doped In₂O₃. Bull Mater Sci 2013, 36(1), 25-9.

Molybdenum-doped indium oxide nanopowders were synthesized via mechanical alloying with subsequent annealing at a relatively low temperature of 600 °C. The morphologies and crystal structures of the synthesized nanopowders were examined by using scanning electron microscopy (SEM) and X-ray diffraction patterns. X-ray diffraction pattern of the milled mixture shows the presence of both In₂O₃ phase and Mo element. The presence of broad peaks in the pattern confirms that the synthesized powders are nanosized. The X-ray diffraction of annealed samples at 600 °C shows the absence of Mo peaks revealing that the Mo was incorporated into the crystal lattices of In₂O₃. Interestingly, it was observed that the diffraction peaks were still broad in the annealed samples indicating the single phase at the nanoscale. From the XRD pattern, the calculated crystallite sizes were in the range of 12-18 nm. Magnetic properties of the synthesized Mo-doped In₂O₃ nanopowders were examined and it was found that the obtained nanopowders possess diamagnetic properties.

3 illus, 2 tables, 19 ref

003225   Jovanovic D J;Validzic I L J;Mitric M; Nedeljkovic J M (Vinca Institute of Nuclear Sciences, Belgrade Univ, P.O. Box 522, 11001 Belgrade, Serbia, Email: validzic@vinca.rs) : Crystal structure studies on plate/shelf like disodium ditungstate. Bull Mater Sci 2013, 36(1), 149-52.

The structure of plate/shelf like disodium ditungstate (Na₂W₂O₇) synthesized by new method in the process of ultrasonic spray pyrolysis using acidified aqueous solutions of tungsten (VI) oxide clusters as a precursor was refined down to the R-factor of 8.9%. X-ray diffraction analysis undoubtedly confirmed formation of orthorhom-bic Na₂W₂O₇ and refinement of the diffraction data showed that Na₂W₂O₇ powder belongs to the base-centred orthorhombic type of structure with 64 space group, Cmca. The structure of Na₂W₂O₇ can be described as infinite chains formed from tetrahedral (WO₄) and octahedral (WO₆) building units joined together. It was found that the basic units of the precursor complexes exist in the structure of Na₂W₂O₇. Scanning electron microscopy confirmed formation of plate/shelf like Na₂W₂O₇ particles with an average thickness of about 1.2 μm.

3 illus, 2 tables, 21 ref