004002   Adam J et al (NO, Joint Institute of Nuclear Research, Dubna near Moscow-141 980, Email: jadam@nusun.jinr.ru) : Transmutation of <. Pramana J Phys 2007, 68(2), 201-12.

Target-blanket facility 'Energy + Transmutation' was irradiated by proton beam extracted from the Nuclotron Accelerator in Laboratory of High Energies of Joint Institute for Nuclear Research in Dubna, Russia. Neutrons generated by the spallation reactions of 0.7, 1.0, 1.5 and 2 GeV protons and lead target interact with subcritical uranium blanket. In the neutron field outside the blanket, radioactive iodine, neptunium, plutonium and americium samples were irradiated and transmutation reaction yields (residual nuclei production yields) have been determined using 7-spectroscopy. Neutron field's energy distribution has also been studied using a set of threshold detectors. Results of transmutation studies of ¹²⁹I, ²³⁷Np, ²³⁸Pu, ²³⁹Pu and ²⁴¹Am are presented.

10 illus, 12 tables, 7 ref

003449   Rao A S;Kalahasti S;Rao B S;Rao N S;Suresh Kumar D;Madhukar K (Physics Dep, Kakatiya Govt College, Hanmakonda) : Radiation effects in gelatins. Int J chem Sci 2009, 7(2), 961-8.

Radiation effects in gelatins have been investigated by electron spin resonance spectroscopy gelatins of different types have been taken and radiation effects have been compared. The ESR spectra of irradiated gelatins were quartet having complicated hyperfine structure. The spectra are thought to be superposition of component spectra arising due to "NHCO (I) and CONH (II) radicals. Radical (I) Gives component quartet while radical (II) gives component singlet. Superposition of these two components will result in the experimentally observed spectrum. Area under ESR spectra were measured using double integration methods and the values are compared. Among the. four gelatins investigated, it was observed that general grade gelatin degrades heavily than the others.

5 illus, 3 tables, 10 ref

003448   Arunkumar T;Jayaprakash R;Perumal K;Sanjay Kumar (Physics Dep, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore-641 020, Email: tarunmsc@yahoo.co.in) : Desalination process of single slope solar still coupled in CPC with crescent absorber. J Envir Res Dev 2010, 5(1), 23-33.

Use of solar energy in thermal desalination processes is one of the most promising applications of the renewable energies. The thermal conversion of solar energy by means of solar concentrators makes it possible to reach high temperatures able to boil the salted water with pressures higher or equal to the atmospheric one. The desalination process is carried out by coupling a single slope solar still with compound parabolic concentrator (CPC). The experiments are carried out at January and February 2010. The newly designed crescent shaped absorber is at the focus of the CPC and its inlet and outlet are connected to the single slope solar still. The performance of the study is analyzed by two different modes. The single slope solar still is coupled with crescent absorber under top cover closed condition to avoid solar radiation which enters into the still alone and the still with open condition for the entry of solar radiation. The area of the still is about 0.25 m². The system temperature such as water (T_w), air (T_air), inner cover (Tin) and outer cover (Tout) are measured by type-K thermocouples and digital thermometers. The humidity and wind velocity are also recorded during the study. The hourly output and instantaneous efficiency are also calculated. The primary focus is on these technologies suitable for use in remote areas, especially those which could be integrated into other solar thermal energy systems.

11 illus, 10 ref

002201   Tripathy P C;Acharya R N;Sahu T (Physics Dep, Rajendra College, Balangir-767 002) : Effect of bond angle and dihedral angle disorder on diamagnetic susceptibility of tetrahedrally coordinated amorphous semiconductors. Indian J Phys 2009, 83(4), 511-5.

The effect of bond angle and dihedral angle disorder on the diamagnetic susceptibility (x) of a model amorphous semiconductor by adopting a linear combination of hybrids formalism. We have constructed orthormal basis states for the disorder network by introducing distortion in bond angles and dihedral angles. We have used the disorder basis states in the expression for x and adopted suitable averaging techniques to obtain x in terms of disorder parameters, which shows interesting results.

1 illus, 1 table, 9 ref

002200   Tripathi G S (Physics Dep, Berhampur Univ, Herhampur-760 007, Email: g.stripathi@hotmail.com) : Semiconductor magnetism: excitements and promises. Indian J Phys 2009, 83(4), 479-84.

Beginning from a historical introduction, we present in this article the current excitements resulting from a possible hybridization of the two important areas of Condensed Matter Physics, namely, semiconductors and magnetism. Both the subjects have contributed to economically important technologies and rich physics, independently. We discuss the physics of diluted magnetic semiconductors (DMS) with special emphasis on the theory of light induced magnetism (LIM), keeping in mind both narrow gap and wide gap DMS.

2 illus, 47 ref

002199   Srivastava A;Gaur N K;Bhardwaj P (Physics Dep, Sri Sathya Sai College for Women, Bhopal-462 024, Email: archanasaran@rediffmail.com) : Effect of heavy cation doping on thermal properties of LaMnO₃. Indian J Phys 2009, 83(4), 437-45.

Effect of heavy cation doping (Ca⁺² at the A-site) on the thermal properties of perovskite LaMnO₃ has been investigated using the Rigid Ion Model (RIM)). As strong electron-phonon interactions are present in these compounds, the lattice part of the specific heat deserves proper attention. The specific heat of magnetoresistance compound La_0.25Ca_0.75MnO₃ as a function of temperature (10 K ≤ T ≤ 300 K) is reported. Our results on specific heat are in good agreement with the measured values of specific heat at lower temperatures. In addition, the results on the cohesive energy (φ), molecular force constant (f), Restrahalen frequency (v₀), Debye temperature (Θ_D) and Gruneisen parameter (γ) are also discussed.

3 illus, 2 tables, 23 ref

002198   Shinde K N;Nagpure I M;Dhoble S J;Godbole S V;Bhide M K (NO, Kamala Nehru Mahavidyalaya, Sakkardara Square, Nagpur-440 009) : Dy<. Indian J Phys 2009, 83(4), 503-9.

Ultrafine M₅(PO₄)₃F:Dy³⁺ (M = Ca, Ba) phosphors were prepared via combustion process using metal nitrates as precursors. The formation of crystalline phosphate was confirmed by X-ray diffraction pattern. The PL excitation spectra show the excitation peaks observed at 250 to 400 nm due to f → f transition of Dy³⁺ ion, which are useful for solid-state lighting purpose (mercury free excitation). The PL emission of Dy³⁺ ion by 348 nm excitation gave an emission at 489 nm (blue), 582 nm (yellow) and 675 nm (red). All the characteristics of BYR emissions like BGR indicate that Dy doped Ca₅(PO₄)₃F and Ba₅(PO₄)₃F phosphors are good candidates that can be applied in solid-state lighting phosphor (mercury free excited lamp phosphor) and white light LED.

3 illus, 16 ref

002197   Samanta A;Srinivasu K;Ghosh S K (Theoretical Chemistry Section, Bhabha Atomic Research Center, Mumbai-400 085) : Work distribution for a particle moving in an optical trap and non-markovian bath. J chem Sci 2009, 121(5), 897-904.

Proposees a simple approach to derive an exact analytical expression of work distribution for a system consisting of a colloidal particle trapped in an optical harmonic potential well, which is being pulled at a constant velocity through a solution represented by a non-Markovian bath. The thermal environment is represented by a bath composed of an infinite set of harmonic oscillators, and a model Hamiltonian for the trapped colloidal particle is constructed by representing the interaction with the bath via linear dissipative mechanism. Studied the effects of pulling time, pulling speed, and the adiabatic limit. It is also observed that only at long time the total work is completely converted into dissipative work.

4 illus, 18 ref

002196   Sahu T;Patra J N;Subudhi P K (Electronic Science Dep, Berhampur Univ, Berhampur-760 007, Email: tsahu_bu@rediffmail.com) : Low temperature electron mobility in Ga_0.5In_0.5P/GaAs quantum well structures. Indian J Phys 2009, 83(4), 547-51.

Analyse the low temperature subband electron mobility in a Ga_0.5In_0.5P/GaAs quantum wel structure where the side barriers are delta-doped with layers of Si. The electrons are transferred from both the sides into the well forming two dimensional electron gas (2DEG). We consider the interface roughness scattering in addition to ionised impurity scattering. The effect of screening of the scattering potentials by 2DEG on the electron mobility is analysed by changing well width. Although the ionized impurity scattering is a dominant mechanism, for small well width the interface roughness scattering happens to be appreciable. Our analysis can be utilized for low temperature device applications.

2 illus, 9 ref

002195   Sahu N;Parija B;Panigrahi S (Physics Dep, National Insitute of Technology, Rourkeal-769 008, Email: nsahu76@gmail.com) : Fundamental understanding and modeling of spin coating process. Indian J Phys 2009, 83(4), 493-502.

A mathematical model is derived to elucidate the dominant mechanism governing film formation. It leads to a relation between film thickness and film radius spreading with time. Inclusion of evaporation and shear stress was made with extension to non-Newtonian fluid. The advantages and disadvantages of this process with applications are reviewed.

^iia1 illus, 10 ref

002194   Rautray T R;Behera B;Badapanda T;Vijayan V; Panigrahi S (Physics Dep, National Insitute of Technology, Rourkela-769 008, Email: tapash77@hotmail.com) : Trace element analysis of fly ash samples by EDXRF technique. Indian J Phys 2009, 83(4), 543-6.

Trace element analysis of some fly ash samples and soil samples have been carried out by Energy Dispersive X:Ray Fluorescence technique. Fourteen elements namely K, Ca, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Sr and Pb have been quantified in the fly ash samples by this technique. It was found that there is no huge concentration difference between the fly ash and soil samples as a result of which fly ash can be used as soil manure without any adverse impact on the plants.

2 illus, 1 tables, 5 ref

002193   Rath H;Anand S;Mohapatra M;Dash P;Som T;Singh U P;Mishra N C (Physics Dep, Utkal Univ, Bhubaneswar-751 004, Email: haripriyarath@gmail.com) : Effect of thermal annealing on the structure and microstructure of TiO₂ thin films. Indian J Phys 2009, 83(4), 559-65.

Nanostructured TiO₂ thin films have been prepared through chemical route using sol-gel and spin coating techniques. The deposited films were annealed in the temperature range 400-1000°C for 1 h. The structure and microstructure of the annealed films were characterized by GAXRD, micro-Raman spectroscopy and AFM. The as-deposited TiO₂ thin films are found to be amorphous. Micro-Raman and GAXRD results confirm the presence of the anatase phase and absence of the rutile phase for films annealed up to 700°C. The diffraction pattern of the film annealed at 800 to 1000°C contains peaks of both anatase and rutile reflections. The intensity of all peaks in micro-Raman and GAXRD patterns increased and their width (FWHM) decreased with increasing annealing temperature, demonstrating the improvement in the crystallinity of the annealed films. Phase transformation at higher annealing temperature involves a competition among three events such as : grain growth of anatase phase, conversion of anatase to rutile and grain growth of rutile phase. AFM image of the as-deposited films and annealed films indicated exponential grain growth at higher temperature.

7 illus, 13 ref

002192   Rath C;Singh S;Mallick P;Pandey D;Lalla N P; Mishra N C (School of Materials Science & Technology, Institute of Technology, Banaras Hindu Univ, Varanasi-221 005, Email: chandanarath@yahoo.com) : Effect of cobalt substitution on microstructure and magnetic properties in ZnO nanoparticles. Indian J Phys 2009, 83(4), 415-21.

Ferromagentic semiconductors have been actively pursued because of their potential as spin polarized carrier sources and easy integration into semiconductor technology. One such material, ZnO has been shown to be a potential Diluted Magnetic Semiconductor (DMS). The appearance of ferromagnetism, however, is found to be sensitive to the processing conditions. We report synthesis of ZnO nanoparticles of size -20 nm by a simple co-precipitation technique using metal nitrates and NaOH as precipitant. The particles are self-organised and reveal single crystalline behaviour in electron diffraction pattern. Incorporation of Co in ZnO matrix leads not only to the reduction in crystallite size but also to the modification of the structure. At 5% Co, the particles are highly textured. The particles also aggregate and the aggregated mass have nearly rectangular shape as seen through TEM. Increasing Co to 10%, results into further reduction of particle size and the particles self organize in a line, which looks like nanofibers. This alignment of particles increases by increasing the Co content further. This type of growth of nanofibers above Co ≥ 10% is well correlated with the anisotropic peak broadening observed in the XRD spectra. In addition, Co substitute Zn site up to 20% without showing any extra phase in XRD spectra as compared to 7 to 10% in case of bulk. Transport and magnetic studies indicate that conductivity increases with increasing Co content, but carrier mediated ferromagnetism is absent down to 10 K.

7 illus, 1 table, 15 ref

002191   Ramasesha S;Sahoo S;Raghunathan R;Sen D (Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560 012, Email: ramasesh@sscu.iisc.ernet.in) : Computing magnetic anisotropy constants of single molecule magnets. J chem Sci 2009, 121(5), 823-37.

Presents here a theoretical approach to compute the molecular magnetic anisotropy parameters, D_M and EM for single molecule magnets in any given spin eigenstate of exchange spin Hami-Itonian. We first describe a hybrid constant M_s-valence bond (VB) technique of solving spin Hamilto-nians employing full spatial and spin symmetry adaptation and we illustrate this technique by solving the exchange Hamiltonian of the Cu₆Fe₈ system. Treating the anisotropy Hamiltonian as perturbation, we compute the D_M and E_M values for various eigenstates of the exchange Hamiltonian. Since, the dipolar contribution to the magnetic anisotropy is negligibly small, we calculate the molecular anisotropy from the single-ion anisotropies of the metal centers. We have studied the variation of D_M and E_M by rotating the single-ion anisotropies in the case of Mn₁₂Ac and Fe₈ SMMs in ground and few low-lying excited states of the exchange Hamiltonian. In both the systems, we find that the molecular anisotropy changes drastically when the single-ion anisotropies are rotated. While in Mn₁₂Ac SMM D_M values depend strongly on the spin of the eigenstate, it is almost independent of the spin of the eigenstate in Fe₈ SMM. We also find that the D_M value is almost insensitive to the orientation of the anisotropy of the core Mn(IV) ions. The dependence of D_M on the energy gap between the ground and the excited states in both the systems has also been studied by using different sets of exchange constants.

18 illus, 7 tables, 37 ref

002190   Panigrahi M R;Badapanda T;Panigrahi S (Physics Dep, National Institute of Technology, Rourkela-769 008) : Theoretical description of ABO3 relaxor ferroelectric. Indian J Phys 2009, 83(4), 567-71.

Significant similarities exist between spin glasses and relaxor ferroelectric. Because of the wealth of available knowledge both in experimental and theoretical aspects in the former, attempt has been made by many workers to deal the relaxor behavior in analogy with the spin glasses. However, the nature of diffused phase transition in relaxor ferroelectric remains controversial. To overcome this difficulty, many workers extended the above model to a new type of dipolar glasses, namely spherical vector glasses in which order parameter field is described as a continuous vector field of variable length instead of fixed length as proposed earlier. The present review is aimed to focus on all the models.

^iia6 ref

002189   Panda S;Rout G C (NO, Trident Academy of Technology, F2/A, Chandaka Industrial Estate, Bhubaneswar-751 024) : Role of CDW gap on the magnetic phase transition in CMR materials. Indian J Phys 2009, 83(4), 465-72.

Proposes a model to study the magnetic phase transition in the Colossal-Magneto-Resistance (CMR) material of general type R_{1 -x}A_xnO₃ (R = La, Sm, Nd; A = Ca, Sr, Ba). The model Hamiltonian consists of a Charge Density Wave (CDW) gap in the e_g-band and the strong magnetic field due to the spin ordering in the localized t_g core electrons. The Hamiltonian is solved by using Zubarev's Green's function technique to calculate CDW gap (Δ) and magnetization (M^d) in t_2g band. Both of them are solved self-consistently. Their combined effect on the temperature dependent magnetization (M^c) due to the e_gband electrons is investigated. Both the magnitude and the transition temperature of (M^c) are strongly influenced by both A and M^d. Hence the hopping of the band electrons are strongly controlled by these two long range interactions. The results are discussed by varying the model parameters of the manganite system.

5 illus, 16 ref

002188   Panda B N;Sahoo B K;Rout G C (NO, D A V College, Koraput-764 021) : Dispersion of quasi-particles in high T_c cuprates. Indian J Phys 2009, 83(4), 447-54.

The interplay between superconductivity (SC) and antiferromagnetism (AFM) is studied in strongly correlated systems of high T_c Cuprate superconductors. It is assumed that superconductivity arises due to BCS pairing mechanism in presence of AFM in Cu lattices of Cu-O planes. The total Hamiltonian of the system is mean field one and has been solved exactly by writing the equations of motion for the single particle Green's functions. Equations for the appropriate single particle co-relation functions are derived and the order parameters corresponding to SC and AFM are determined. It is assumed that the Fermi energy ∈_F = 0 and the renormalized localized f energy level coincide with the Fermi level. All the quantities in the final equation for h and Δ are made dimensionless by dividing by 2t, where t is the hopping integral. The temperature dependent values of staggered magnetic field (h) and SC gap (Δ) were determined by solving self-consistent equations for h and Δ. The quasi-particle energy bands are function of AFM gap (h), SC gap (Δ) and hybridization (V). Then the dispersion of quasi-particles are studied at different temperatures by considering temperature dependent values of h and Δ and varying other different model parameters.

4 illus, 12 ref

002187   Nath G;Sahu S;Paikaray R (Physics Engineering Dep, Dhaneswar Rath Insitute of Engg. and Management studies (D.R.I.M.S.), Tangi, Cuttack-754 022, Email: ganesh_nath99@yahoo.co.in) : Acoustic parameters of binary mixtures of a nonpolar liquid with polar liquid at different frequencies. Indian J Phys 2009, 83(4), 429-36.

The densities (p) and ultrasonic velocities (C) of binary mixture of diisopropyl ether (DIPE) and bromobenzene (BB) have been measured at different frequencies (1 MHz, 3 MHz and 5 MHz) over the entire range of mole fraction of diisopropyl ether (DIPE) at temperature 303 K. The intermolecular free length (L_f), isentropic compressibility (0), acoustic impedance (Z) and excess values of isentropic compressibility (β^E) and acoustic impedance (Z^E) have been computed using values of ultrasonic velocity (C) and density (p). The ultrasonic velocity, intermolecular free length are positive whereas the excess values of isentropic compressibility and acoustic impedance are negative over the entire composition range of DIPE which indicates presence of specific interactions between unlike molecules. The results are discussed in the light of intermolecular interactions occurring in the mixtures.

4 illus, 1 table, 37 ref

002186   Mohanta A;Behera D;Panigrahi S;Mishra N C (Physics Dep, National Institute of Technology, Rourkela-769 008) : Intergranular percolation in granular YBCO/BaTiO₃ composites. Indian J Phys 2009, 83(4), 455-63.

Ferroelectrics and high temperature superconductors are two promising materials for future electronic devices. Both being perovskite ceramic structures with similar crystal chemistry a set of samples were prepared from the composite of (1 -x)YBa₂Cu₃0_{7 - 5} - (x)BaTiO₃ (YBCO/BT). These samples were investigated with temperature dependent resistance, FTIR, X-ray diffraction and SEM-EDX analysis. It has been found that the critical exponent in the T_c0 (R= 0) region is in agreement with the percolation theory. A long-range superconducting order results from thermally assisted percolation process through weak-links between the grains. The connectivity in the coherent transition region can be explained by a power law.

7 illus, 2 tables, 12 ref

002185   Mallick P;Rath C;Biswal R;Mishra N C (Physics Dep, North Orissa Univ, Baripada-757 003, Email: pravanjan_phy@yahoo.co.in) : Structural and magnetic properties of Fe doped NiO. Indian J Phys 2009, 83(4), 517-23.

Mott-Hubbard anti-ferromagnetic insulator, NiO shows p-type semiconducting behaviour due to vacancy at Ni²⁺site in its bunsenite structure. We report the modification of structural and magnetic order in NiO on Fe doping. NiO samples at different Fe concentrations in the range 0 to 5 at.% have been prepared by chemical co-precipitation and post thermal decomposition method. Both structural and magnetic characterization reveal that with increasing Fe doping concentration, NiO evolves as a magnetically inhomogeneous state out of the parent homogeneous antiferromagnetic state. In addition, structural inhomogeneity was also observed with Fe precipitating to γ-Fe₂O₃ phase, the signature of which could be clearly seen for Fe content beyond 2 at.%. At lower Fe content however, some amount of Fe occupies lattice and interstitial sites in the NiO matrix and drive the latter to acquire ferromagnetic ordering, which was evident from a clear hysteresis loop at 300 K.

4 illus, 19 ref

002184   Mallick B;Behera R C;Panigrahi S;Badapanda T; Parija B;Behera B;Panigrahi M;Sarangi M (Physics Dep, National Institute of Technology, Rourkela-769 008, Email: bmallick_iopb@scientist.com) : Microstructural analysis of neutron-irradiation induced changes in polyester fibre studied using EPMA. Indian J Phys 2009, 83(4), 525-9.

Electron microscopy is an important characterization technique for the study of textile fibre as it gives more information on fabric wear, nature of fibre fracture, chemical degradation, abrasion, fatigue and many others. Electron Probe Micro Analyzer (EPMA) micrographs of virgin and some neutron-irradiated samples (graphite coated) are discussed. The filament diameter, D, of virgin PET fibre obtained from EPMA study was 12.5 μn. The surface topography of single filament distinctly reveals the core and sheath parts of the filament. The core diameter of the virgin fibre was estimated to be 1.43 μm. The fibre irradiated at fluence 1 x 10¹² n/cm² shows radiation induced sphere like polymer balls or spherulites of diameter 2.27 p,m in the expanded core region. Due to irradiation, the sheath area crosslinks with expanded core region, which may be responsible for increase of strength and hardness of the polymer materials. Moreover, the micrograph at 3000 X magnifications clearly shows that there is no preferred orientation of the polymer in any direction confirming the isotropic nature of the sample.

1 illus, 16 ref

002183   Kiranmayi L;Bhat G S (Center for Atmospheric and Oceanic Science, Indian Institute of Science, Bangalore-560 012, Email: bhat@caos.iisc.ernet.in) : Equatorial modes observed in atmospheric variables. J Earth Syst Sci 2009, 118(3), 181-92.

Wavenumber-frequency spectral analysis of different atmospheric variables has been carried out using 25 years of data. The area considered is the tropical belt 25°S 25°N. A combined FFT-wavelet analysis method has been vised for this purpose. Variables considered are outgoing longwave radiation (OLR), 850 hPa divergence, zonal and meridional winds at 850, 500 and 200 hPa levels, sea level pressure and 850 hPa geopotential height. It is shown that the spectra of different variables have some common properties, but each variable also has few features different from the rest. While Kelvin mode is prominent in OLR and zonal winds, it is not clearly observed in pressure and geopotential height fields; the latter two have a dominant wavenumber zero mode not seen in other variables except in meridional wind at 200 hPa and 850 hPa divergences. Different dominant modes in the tropics show significant variations on sub-seasonal time scales.

8 illus, 35 ref

002182   Katyal R;Gomathinayagam S (Research & Development Centre for Wind, Energy Technology (c-WET), Chenni-600 100, Email: katyal@cwet.res.in) : Better understanding of our fuel: wind. Energy Fuel Users J 2010, 59(4), 1-7.

Unlike many other energy sources whose quantum and desirable rate can be precisely estimated, wind cannot be. Being stochastic in nature only predictions can be made and power generation guarantees with large range of uncertainty can be provided. Based on past data and experience a trend can be established whose reliability can be improved with the consideration of as many variables as possible and consequently the predictive model becomes complicated. To ease out the large error margins, regular fine tuning and benchmarking with recently measured data have to be done. This model pruning keeps it as close as possible to actual on ground.

1 illus, 4 ref

002181   Hota M;Tripathy S K (NO, National Institute of Science and Technolgoy, Palur Hills, Berhampur-761 008) : Analysis of diffraction efficiency of a holographic coupler with respect to angular divergence. Indian J Phys 2009, 83(4), 531-8.

Presents a method to optimize the Coupling efficiency between two fibers using a Holographic Coupler taking diffraction effect into account. For this we obtain expressions for field distributions at the end facet of a fiber. The results obtained by using the expression is found to be in good agreement with the finite element method in literature, the small deviation is attributed to the negligence of field in the cladding. We then use the Kogelnik theory to obtain useful formulae suitable for diffracted optical elements. The diffraction efficiency expressions are then used to predict the different parameters of Holograting so as to get maximum diffraction efficiency in a direction where the field distribution from the end facet is minimum thereby increasing the coupling efficiency.

6 illus, 11 ref

002180   Gogoi A;Ahmed G A;Choudhury A (Physics Dep, Tezpur Univ, Tezpur-784 028, Email: ankur@tezu.emet.in) : Nanoparticle size characterization by laser light scattering. Indian J Phys 2009, 83(4), 473-7.

Spherical semiconductor nanoparticles (ZnS) were specially fabricated by an inexpensive chemical route. The scattering profile of the nanoparticles was investigated by laser light scattering technique. A beam of polarized light from a diode laser (λ₀ ≈ 630 nm) was allowed to fall on the nanospheres embedded in flexible host matrix Polyvinyl Alcohol (PVA). The light scattered from the samples were detected by means of analyzer mounted photodiode array from 10° to 170° in steps of 1°. Signals from the detectors were interfaced with a high resolution data acquisition system and the whole experiment was carried out in differential mode. Size of the nanoparticles was obtained by using Mie theory and verified by T-matrix approach. The results obtained agree with the XRD and TEM results.

4 illus, 11 ref

002179   Deshmukh A D;Dhoble S J;Godbole S V;Bhide M K;Peshwe D R (NO, Kamla Nehru College, Sakkardara Square, Nagpur-440 009, Email: abhy_d1984@yahoo.co.in) : Intense blue-emitting Ca₅AI₈O₁₄: Eu phosphor for mercury free lamp. Indian J Phys 2009, 83(4), 423-8.

The calcium aluminates doped with Eu ions, Ca₅AI₈O₁₄ : Eu, phosphors are prepared by the combustion method. The formation of crystalline aluminates was confirmed by X-ray diffraction pattern. The prepared phosphors were characterized by SEM, TGA, DTA, particle size analyzer and Photoluminescence (PL) techniques. From the UV-excited luminescence spectra it was found that the Eu ions acts as a luminescent centre with luminescence at the blue (λ_max = 470 nm) region due to 4f⁶5d¹ → 4f⁷ transition. The excitation spectra show the broad band at 355 nm wavelength (λ_em = 470 nm). The excitation 355 nm is a mercury free excitation and therefore Ca₅AI₈O₁₄ : Eu may be useful for the solid state lighting phosphor in lamp industry.

7 illus, 8 ref

002178   Dash P;Dash B N;Rath H;Rath C;Mishra N C (Physics Dep, Utkal Univ, Bhubaneswar-751 004, Email: lipundash16@yahoo.com) : Evolution of phase purity and texture on annealing of BiFeO₃ thin film prepared by sol-gel technique. Indian J Phys 2009, 83(4), 485-91.

Reports preparation of phase pure BiFeO₃ thin films on glass, ITO and Si(100) substrates through chemical route using spin coating technique. Sol-gel process was adopted to prepare the films using bismuth nitrate and iron nitrate as precursors. X-Ray diffraction and Raman spectroscopy studies revealed amorphous nature of the as deposited films. Rhombohedral crystalline phase of BiFeO₃ evolved on annealing the films at 500°C, but with Bi₂Fe₄O₉ and Bi₂₄Fe₂O₃₉ as impurity phases. Increasing the annealing temperature to 550°C caused a drastic reduction of the impurity phases and at 600°C, the films were phase-pure BiFeO₃. Micro Raman spectra showed features consistent with the reported characteristic peaks of BiFeO₃ crystalline phase for films annealed at 500 and 550°C. Crystallite size obtained from X-ray diffraction line width analysis are within 30 to 40 nm. Atomic force microscopy (AFM) however showed grain size of -192 nm, indicating polycrystalline nature of the grains.

3 illus, 1 table, 19 ref

002177   Chakraborty R;Das U;Mohanta D;Choudhury A (Physics Dep, Tezpur Univ, P.O. Npaam, Tezpur-784 028) : Fabrication of ZnO nanorods for optoelectronic device application. Indian J Phys 2009, 83(4), 553-8.

Hydroxyl free zinc oxide nanorods have been synthesized by a catalyst free surfactant based one-step solid state reaction process. The powder X-ray diffraction studies reveal well defined wurtzite peaks due to crystalline ZnO, while optical absorption spectra represent prominent exciton absorption and remarkable blueshift in the onset of absorption. As predicted by transmission electron microscopy, the ZnO nanorods are -100 nm long and of <126>20 nm dia. Further, luminescence aspects of such nanorods are studied for possible deployment in optoelectronics devices.

4 illus, 28 ref

002176   Bimal S;Khan A A;Dey K K;Roy S S (Physics Dep, B. I. T., Sindri, Dhanbad, Jharkhand-828 123, Email: sn_bimal@yahoo.com) : Wien bridge oscillator using current conveyors. Asian J expl Sci 2010, 24(2), 283-9.

In this paper, three new Wien bridge oscillator circuits using AD844 configured as second-generation current conveyors are proposed, analyzed and studied experimentally. Other important effects such as the influence of voltage and current tracking errors on the circuit's performance are studied. In all the three circuits it has been found that the voltage and current tracking errors associated with AD844 do not affect the frequency of the oscillations. The circuits proposed are attractive for integration.

12 illus, 1 table, 13 ref

002175   Bhattacharjee S;Baishya B (Physics Dep, Dibrugarh Univ, Dibrugarh-786 004, Email: suparna_bhattacharjee2000@yahoo.com) : Electrical properties of thin films of Eu₂O₃ substituted compounds. Indian J Phys 2009, 83(4), 539-42.

Europium oxide (Eu₂O₃) substituted comgouncUias been prepared by solid-solid reaction of the powders of Eu₂O₃, BaCO₃ and CuO at 950°C for 16 hours. The thin films have been deposited by high vacuum evaporation technique (vacuum ≈10^-6 torr). The variation of current (I) with voltage (V) at room temperature (RT) i.e. 294 K and in ice (273 K) are found to be linear. The variation of electrical resistivity (ρ) with temperature (T) by heating the sample above FIT has been determined. Resistivity is found to decrease with increase in temperature. Further the variation of electrical resistivity (ρ) with temperature (T) from 77 K, liquid nitrogen temperature (LNT), to 270 K has also been determined. It is observed that resistivity suddenly becomes zero at around 87 K. Thus the prepared material has superconducting properties with superconducting transition temperature, T_c at 87 K.

3 illus, 5 ref

002174   Bharti C;Choudhary S N;Sinha T P (Physics Dep, T M Bhagalpur Univ, Bhagalpur-812 007, Email: bharti_chandrahas@yahoo.com) : Ferroelectric relaxor behaviour in Pb (Fe_0.5Ta_0.5)O₃. Indian J Phys 2009, 83(4), 409-14.

The relaxor ferroelectric lead iron tantalate, Pb(Fe_0.5Ta_0.5)O₃ (PFT) is synthesized by Coulombite precursor method. The X-ray diffraction pattern of the sample at room temperature shows a cubic phase. The field dependence of dielectric response is measured in a frequency range 0.1 kHz - 1 MHz and in a temperature range from 173-373 K. The temperature dependence of permittivity (ε') shows broad maxima at various frequencies. The frequency dependence of the permittivity maximum temperature (T_m) has been modelled using Vogel-Fulcher relation.

4 illus, 14 ref

002173   Atul Kumar;Krishnan M S (Chemistry Dep, Indian Institute of Technology Madras, Chennai-600 036) : Quantum entanglement and teleportation using statistical correlations. J chem Sci 2009, 121(5), 767-75.

A study of quantum teleportation using two and three-particle correlated density matrix is presented. A criterion based on standard quantum statistical correlations employed in the many-body virial expansion is used to determine the extent of entanglement for a 2N-particle system. A relation between the probability and statistical parameters is established using the correlated density matrices for the particles.

5 tables^i31 ref

003096   Zhou Y F;Xu J Y;Liu Y;Chen L D;Huang Y Y; Huang W X (NO, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai-200 050, Email: zhouyf@mail.sic.ac.cn) : Influence of microgravity on Ce-doped Bi₁₂SiO₂₀ crystal defect. Bull Mater Sci 2007, 30(3), 211-14.

Space grown BSO crystal doped with Ce was characterized by means of X-ray fluorescence spectra, X-ray topography, dislocation density etc. Influence of microgravity on Ce-doped BSO crystal defect was studied by comparing space grown BSO crystal with ground grown one. These results show that composi-tional homogeneity and structural perfection of crystal can be improved under microgravity conditions.

7 illus, 13 ref

003095   Yadav R K P;Das M (P.G. Physics Dep, B.N. Mandal University, Madhepura-852 113) : Electronic structure calculation of semi conductor clusters: a tight binding approximation. Appl Sci Period 2006, 8(2), 146-9.

Tight Binding (TB) scheme has been used to carry out electronic structure calculations of silican clusters of sizes up to 40 Angstrom. In this method 4-non orthogonal orbitals per-site where many neighbour interactions are taken into account have been employed. These calculations have been carried out for passivated and unpassivated clusters. Comparison with results obtained by other research groups to give a satisfactory account of different features of nano materials mentioned above.

1 illus, 7 ref

003094   Yadav J;Rafique S M (NO, , Khunt, Koriapatti, Supaul-852 214) : Superconducting parameters of metals and alloys: HFP technique. Indian J Phys 2007, 81(1), 161-5.

The superconducting parameters of metals and alloys have been studied within the framework of BCS theory via McMillan technique for different metals and alloys using Harrisons First Principles (HFP) pseudopotential. This technique is being used for the first time for this investigation although it is more rigorous and based on sound theoretical background. Studied the electron phonon coupling strength λ, Coulomb pseudopotential μ*, superconducting transition temperature T_c of MgAI and ZnAI binary alloys. The results are compared with available experimental and theoretical data giving a reasonable agreement and providing an insight into the systems under investigation.

1 table, 17 ref

003093   Upadhyay S B;Kant K;Prasad R;Sharma G S (Physics Dep, B.S.A. College, Mathura, Uttar Pradesh, Email: kkant_67@rediffmail.com) : Radon dosimetry in the dwellings of Western U.P. using plastic track detectors. Chem envir Res 2006, 15(4), 271-6.

Annual effective dose due to radon, thoron and their progeny present in the environment of dwellings in Western U.P. was measured, as it is very much essential from health and hygiene point of view to asses the total radiation dose the inhabitants receive. The plastic track detectors (LR-115) were exposed in the mixed field of radon and thoron present in the atmosphere. The calculated values of potential alpha energy concentration (PAEC) for radon and thoron, radon and thoron concentration, total annual effective and inhalation dose in the dwellings are presented. The potential alpha energy concentration for radon and radon concentration varies from 7.80 m WL to 22.27 mWL with a geometric mean (GM.) value of 12.25 ± 0.96 mWLand 74 Bqm-3 to 206 Bq m^-3 with GM value of 113.46± 8.82 Bq m^-3, whereas for thoron it varies from 0.16 mWL to 1.11 mWL with GM.-value of 0.38 ± 0.06 mWL and 6 Bq m^-3 to 41 Bq m^-3 with GM value of 1422 ± 2.43 Bq m^-3. The total annual effective dose due to radon and thoron progeny and inhalation dose due t6 radon and thoron varies from 1.28 mSv/y to 3.63 mS/y with GM value of 2.04 ± 0.16 mSv/y and from 2.14 mSv/y to 5.39 mSv/y with GM. value of 3.39 ± 0.24 mSv/y respectively. The inhalation dose due to radon and thoron in the dwellings near the refmery and the most ponuted zone. in the big cities was found higher than in the dwellings which were well ventilated and located in clean and green areas.

1 illus, 1 table, 16 ref

003092   Thakur O P;Singh J P;Chandra Prakash;Pran Kishan (NO, Solid State Physics Lab, New Delhi-110 054) : Modified lead-zirconate-titanate for pyroelectric sensors. Def Sci J 2007, 57(3), 233-9.

Pyroelectric sensors based on ceramic materials have found applications in IR detection in defence and civil systems. To develop suitable ceramic material for IR detector applications, a modified PZT system with compositional formula Pb_1-xSm_x(Zr_0.58Fe_0.18Mn_0.02Nb_0.2Ti _0.2) O₃ where O ≤ x ≤ 0.025 was synthesised by conventional solid state reaction method. The materials were characterised for their properties like dielectric and pyroelectric coefficient. Hysteresis loop was recorded at room temperature. The sample with 2 mole per cent samarium (Sm) substitutions was found to be more promising for sensor application based on its high material's figure of merit (FOM). Sensors fabricated with this material were integrated with FET amplifier. The devices configured with compensating element were evaluated for different chopping frequencies. The value of material's FOM, F_D, and detectivity, D*, were determined from measured parameters and were, 3.6 x 10^-5 Pa^-l/2 and 2 x 10⁸ cmHz^1/2/W, respectively.

10 illus, 1 table, 14 ref

003091   Thakkar R;Patel H;Chudasama U (Applied Chemistry Dep, Faculty of Technology and Engineering, M.S. Univ Baroda, Vadodara-390 001, Email: uvcres@gmail.com) : Comparative study of proton transport properties of zirconium phosphate and its metal exchanged phases. Bull Mater Sci 2007, 30(3), 205-9.

New phase of amorphous zirconium phosphate (ZrP), an inorganic ion exchanger of the class of tetravalent metal acid (TMA) salt, is synthesized by sol-gel method. The protons present in the structural hydro-xyl groups indicate good potential for TMA salts to exhibit solid state proton conduction. Cu²⁺ and Ei⁺ are exchanged onto ZrP to yield CuZrP and LiZrP exchanged phases. All these materials were characterized for elemental analysis (ICP-AES), thermal analysis (TGA, DSC), X-ray analysis and FTIR spectroscopy. The transport properties of these materials were explored and compared by measuring conductance at different temperatures using an impedance analyser. It is observed that conductivity decreases with increasing temperature in all cases and mechanism of transportation is proposed to be Grotthuss type. Conductivity performance of ZrP, CuZrP and LiZrP is discussed based on conductivity data and activation energy.

6 illus, 35 ref

003090   Tanwar A;Tripathi B;Singh P J;Singh M;Vijay Y K (Physics Dep, University of Rajasthan, Jaipur, Rajasthan) : Positron annihilation study of free volume in blends of polysulphone and poly (methyl methacrylate). Chem envir Res 2006, 15(4), 338-43.

Blends of polysulphone (PSF) and poly (methyl methacrylate) (PMMA) have been prepared by using cast technique. The change in free volume in the blends of polysulphone and poly (methyl. methacrylate) is characterized by Positron Annihilation Lifetime measurements. The changes in free volume density in the blends are observed. The increase in intensity (I₃) component in blends of PSF and PMMA shows the increase in free volume density. Optical micrographs of the blends have been taken to get an insight of the morphology of the blends. The resulting blends of PMMA and PSF are found to be of immiscible category.

1 illus, 1 table, 15 ref

003089   Suman C K;Prasad K;Choudhary R N P (University Physics Dep, T M Bhagalpur University, Bhagalpur-812 007) : Dielectric relaxation in tungsten-bronze Pb₂Bi₃NdTi₅O₁₈ferroelectric. Indian J Phys 2007, 81(1), 117-23.

Single phase orthorhombic tungsten bronze ceramics of Pb₂Bi₃NdTi₅O₁₈ were prepared by a high temperature solid-state reaction method. Dielectric studies show the relaxor like behaviour. The frequency dependence of the temperature of the permitivity maximum has been modeled using Vogel-Fulcher relation. The dielectric relaxation in PBNT is found to be analogous to the magnetic relaxation in spin-glass system. Complex impedance analysis indicated the dielectric relaxation to be of non-Debye type and negative temperature coefficient of resistance type behaviour. The activation energy (E_a = 0.63 eV) has been estimated from the temperature variation of relaxation times.

8 illus, 32 ref

003088   Singh S;Sandhu A K (Physics Dep, Guru Nanak Dev University, Amritsar-143 005, Email: surinder51@yahoo.com) : Comparison of the effects of gamma rays and neutron on the optical and etching properties of the microscopic glass slide used as solid state nuclear track detector. Chem envir Res 2006, 15(4), 215-22.

Comparative study of the effects of the gamma rays and neutrons on the optical and etching properties of the microscopic glass slides have been carried out. Both the radiations result in the colour transformation of the samples. Band gap energy is observed to decrease with the gamma and neutron dose indicating an increase in the conductivity. Both the bulk and the track etch rates are observed to increase with the dose of the gamma and neutron radiations. Thus, both the types of the radiations show similar effects on the microscopic glass slides.

8 illus, 4 tables, 12 ref

003087   Singh S;Mehra R;Singh K (Physics Dep, Guru Nanak Dev University, Amritsar, Punjab, Email: surinder51@yahoo.com) : Measurement of indoor radon concentration in dwellings belonging to Malwa region of Punjab, using solid state nuclear track detectors. Chem envir Res 2006, 15(4), 242-6.

The indoor radon concentration is measured in dwellings belonging to Malwa region of Punjab using LR-115 plastic track detectors. The annual average indoor radon value in the study area varies from 54 Bq m^-3 to 168 Bq m^-3, which is well within the recommended action level. The annual effective dose and average lifetime fatality risk for the dwellings have also been calculated. The annual effective dose received by the residents of the study area varies from 0.92 m Sv to 2.87 m Sv. In all the villages surveyed the annual effective dose is less than even the lower limit of the recommended action level (3 -10m Sv per year). The life time fatality risk of the residents of the study area varies from 0.71 x 10^-4 to 2.22 x 10^-4.

1 illus, 1 table, 10 ref

003086   Singh S C;Gopal R (Physics Dep, Allahabad Univ, Allahabad-211 002, Email: spectra2@rediffmail.com) : Zinc nanoparticles in solution by laser ablation technique. Bull Mater Sci 2007, 30(3), 291-3.

Colloidal zinc metallic nanoparticles are synthesized using pulsed laser ablation of metal plate in an aqueous solution of suitable surfactant to prevent aggregation. UV-visible absorption, TEM, small angle X-ray diffraction and wide-angle X-ray diffraction are used for the characterization of colloidal zinc metallic nanoparticles. Colloidal nanoparticles are found highly stable for a long time.

4 illus, 1 table, 21 ref

003085   Singh H;Singh J;Bajwa B S;Singh S (Physics Dep, Guru Nanak Dev University, Amritsar-143 005, Email: harman_edu@rediffmail.com) : Uranium, radium and radon exhalation rate in the soil samples from some areas of Punjab, India using LR-115 plastic track detectors. Chem envir Res 2006, 15(4), 313-19.

Uranium radium concentration and radon exhalation rate have been determined in soil samples from Amritsar to Zira belt of Punjab using solid-state nuclear track detectors. `Can Technique' has been used for the estimation of radium concentration and radon exhalation rate. Uranium concentration has also been determined in the soil samples using the fission track technique. Uranium content observed has been found to be varying from 1.03 ppm to 551 ppm. Radium concentration observed has been found to be varying from 0.80 to 5.34 BqKg^-l. The radon exhalation rate in these samples has been found to be varying from 1.03 to 4.50 niBqKg^-1h^-1. A correlation factor (R² = 0.61) has been observed between uranium content and radon exhalation rate in these soill samples. Similarly a correlation factor (R² = 0.51) has been observed between the radium and exhalation rate in these samples along this track.

2 illus, 1 table, 16 ref

003084   Sharma S;Ogura K;Pandey A K;Ojha D K;Bhatt B C (NO, Aryabhatta Res Inst of Observational Sci(ARIES), Nainital) : Near-infrared JH photometry of young open cluster Be 59. Bull Astr Soc India 2007, 35(1), 53-63.

Present near-infrared J H photometry and optical slitless spectroscopy of stars in the field of the young cluster Be 59. The J/(J - H) colour-magnitude diagram of the cluster yields a distance modulus of (m - M)₀ = 10.0± 0.2 mag, which corresponds to a distance of 1.0± 0.1 kpc. Using the slit less spectroscopy identified 9 Hα emission line stars in the observed region. The location of Hα stars in the CMD indicates that they may be pre-main sequence stars. Authors have estimated the age of the cluster using the turn-off and turn-on points and is found to lie between <126> 1 Myr to 4 Myr. Two massive stars (<126> 25 M) in the cluster region have high membership probability which indicates that the low mass stars (<126> 0.8 M) may co-exist with massive stars.

6 illus, 3 tables, 12 ref

003083   Shah A K;Gajjar P N (NO, Sheth R A Bhavan's Science College, Khanpur, Ahmedabad-380 001) : Growth and characterization of tungsten substituted molybdenum disulfide. Indian J Phys 2007, 81(1), 131-5.

Single crystals of Mo_0.5W_0.5S₂ have been grown by chemical vapour transport technique with iodine as transporting agent. The identity of the grown crystals has been verified using EDAX technique. Electrical resistivity measurements have been carried out using Van der Pauw technique. The resistivity at room temperature along the basal plane has been found to be 10.62 ohm.cm. The temperature variation of electrical resistivity for low temperature (70-300 K) and high temperature (313-443 K) is reported. The Hall effect measurements on the grown crystals have also been carried out thereby evaluating the Hall mobility and carrier concentration in the grown crystal. The obtained value of negative Hall coefficient conform n type nature of the crystal having carrier concentration 2.2 x 10¹⁴ cm^-3.

4 illus, 21 ref

003082   Seethalakshmi Ammal M;Isac J (Centre for Condensed Matter, Phys Dep, C.M.S. Coll, Kottayam, Kerala-686 001, Email: jaya_cms@yahoo.co.in) : Effect of light energy on the growth of cholesterol crystals. Sci Soc 2007, 5(2), 161-8.

Growth of cholesterol crystals in gel medium under different concentration of the top solution and various pH of the gel in the presence and absence of visible light were studied. The rate of nucleation, morphology and number of crystals were found to be different in the presence of light energy and its absence.

8 illus, 5 tables, 11 ref

003081   Salehi H (Physics Dep, Shahid Chamran Univ, Ahvaz, Iran, Email: Salehi_h@cua.ac.ir) : Sr - doping effect on the electronic structure of BaTiO₃ ceramic. Indian J Phys 2006, 80(12), 1195-1200.

The effects produced in BaTiO₃ ceramic due to Sr-doping have been studied. The investigation has been performed using the Full Potential-Linearized Augmented Plane Wave (FP-LAPW) method in the framework of the Density Functional Theory (DFT) with the generalized gradient approximation (GGA) by WIEN2k package. A supercell consisting of 40 atoms has been used throughout the work. In the present study the electronic structure, density of state and elecironic density of supercell have been calculated. The results show a direct band gap of 2 eV at the Γ -point in the Brillouin zone, while the band gap of pure BaTiO₃ is at the point of 1.8 eV. The calculations show that the chemical character of the lower valence bands mainly is O- 2s in nature, while the upper valence band is predominanlly O- 2p in nature with a small admixture of Ti- 3d and Sr. The bottom of the conduction band is composed mainly of Ti- 3d states, with SOl1)e admixture of Ba-5s state and Sr d-states. A notable contribution of O- 2p states in the lower part of the conduction band is also found. This points out to the hybridization effect between Ti-3d and O- 2p atomic orbitals while the basic contribution of Sr in conduction band up is Ti -3d e.

6 illus, 21 ref

003080   Sahu T (Electronic Science Dep, Berhampur University, Berhampur-760 007, Email: tsahu_bu@rediffmal.ocm) : Electron transport in barrier delta-doped coupled quantum well structures. Indian J Phys 2007, 81(1), 17-23.

Reviews the work done on low temperature electron subband mobility μ_n in various δ-doped systems. Author analyses μ_n in double quantum well structures, which exhibits the tunneling coupling in addition to confinement effect. Disiscusses the importance of intersubband coupling on μ_n in a multisubband system. The effect of screening of the scattering potentials by 2DEG on subband electron mobility is also highlighted.

48 ref

003079   Rout S K;Panigrahi S (Physics Dep, National Institute of Technology, Rourkela-769 008, Email: skrout@nitrkl.ac.in) : BaTi_0.4Zr_0.6O₃ solid solution: phase formation kinetics and reaction mechanism through solid oxide reaction. Indian J Phys 2007, 81(1), 143-7.

The formation of solid solution BaTi_0.4Zr_0.6O₃, from BaCO₃, TiO₂ and ZrO₂ powders has been studied through solid-oxide reaction using TGA/DSC, XRD. Detailed phase formation behavior and reaction mechanism were studied and reported.

4 illus, 1 table, 8 ref