003224   Dey R M;Deshpande S K;Singh S B;Chand N;Patil D S;Kulkarni S K (DST Unit on Nanoscience, Physics Dep, Pune Univ, Pune-411 007, Email: ravi.dey@sunysb.edu) : X-ray reflectivity study of bias graded diamond like carbon film synthesized by ECR plasma. Bull Mater Sci 2013, 36(1), 9-14.

Diamond like carbon (DLC) coatings were deposited on silicon substrates by microwave electron cyclotron resonance (ECR) plasma CVD process using plasma of Ar and CH4 gases under the influence of negative d.c. self bias generated on the substrates by application of RF (13.56 MHz) power. The negative bias voltage was varied from -60 V to -150 V during deposition of DLC films on Si substrate. Detailed X-ray reflectivity (XRR) study was carried out to find out film properties like surface roughness, thickness and density of the films as a function of variation of negative bias voltage. The study shows that the DLC films constituted of composite layer i.e. the upper sub surface layer followed by denser bottom layer representing the bulk of the film. The upper layer is relatively thinner as compared to the bottom layer. The XRR study was an attempt to substantiate the sub-plantation model for DLC film growth.

5 illus, 2 tables, 24 ref

003223   Cronje S;Kroon R E;Roos W D;Neethling J H (Physics Dep, Free State Univ, Bloemfontein, South Africa, Email: cronjes@ufs.ac.za) : Twinning in copper deformed a high strain rates. Bull Mater Sci 2013, 36(1), 157-62.

Copper samples having varying microstructures were deformed at high strain rates using a split-Hopkinson pressure bar. Transmission electron microscopy results show deformation twins present in samples that were both annealed and strained, whereas samples that were annealed and left unstrained, as well as samples that were unannealed and strained, are devoid of these twins. These deformation twins occurred at deformation conditions less extreme than previously predicted.

8 illus, 1 table, 9 ref

003222   Choudhary K K (Physics Dep, Shri Vaishnav Institute of Technology and Science, Indore-453 331, Email: kkchoudhary1@yahoo.com) : Interpretation of anomalous normal state optical conductivity of K₃C₆₀ fullerides. Bull Mater Sci 2013, 36(1), 65-70.

The observed frequency dependent optical response of alkali-metal-doped fulleride superconductors (T_c ≈ 19 K) has been theoretically analysed. The calculations of the optical conductivity, σ (ω), have been made within the two-component schemes: one is the coherent Drude carriers (electrons) responsible for superconductivity and the other is incoherent motion of carriers from one atom to other atom of C₆₀ molecule to a pairing between Drude carriers. The approach accounts for the anomalies reported (frequency dependence of optical conductivity) in the optical measurements for the normal state. The model has only one free parameter, the relaxation rate. The frequency dependent relaxation rates are expressed in terms of memory functions. The coherent Drude carriers form a sharp peak at zero frequency and a long tail at higher frequencies, i.e. in the infrared region. However, the hopping of carriers from one atom to the other (incoherent motion of doped electrons) yields a peak value in the optical conductivity centred at mid-infrared region. It is found that both the Drude and hopping carriers will contribute to the optical process of conduction in the K₃C₆₀ and shows similar results on optical conductivity in the mid-infrared as well as infrared frequency regions as those revealed from experiments.

1 illus, 28 ref

003221   Angadi B;Ajith M R;Umarji A M (Materials Research Centre, Indian Institute of Science, Bangalore-560 012, Email: brangadi@gmail.com) : Synthesis, microstructure and thermal expansion studies on Ca_0.5+x/2Sr_0.5+x/2Zr₄P_6-2xSi_{2x< D>O24 system prepared by co-precipitation method.} Bull Mater Sci 2013, 36(1), 87-91.

Reported on the synthesis, microstructure and thermal expansion studies on Ca_0.5+x/2Zr₄ P_6-2x Si_2xO₂₄(x = 0-00 to 1.00) system which belongs to NZP family of low thermal expansion ceramics. The ceramics synthesized by co-precipitation method at lower calcination and the sintering temperatures were in pure NZP phase up to x = 0.37. For x ≥ 0.5, in addition to NZP phase, ZrSiO₄ and Ca₂P₂O₇ form as secondary phases after sintering. The bulk thermal expansion behaviour of the members of this system was studied from 30 to 850 °C. The thermal expansion coefficient increases from a negative value to a positive value with the silicon substitution in place of phosphorous and a near zero thermal expansion was observed at x = 0.75. The amount of hysteresis between heating and cooling curves increases progressively from x = 0.00 to 0.37 and then decreases for x <62> 0.37. The results were analysed on the basis of formation of the silicon based glassy phase and increase in thermal expansion anisotropy with silicon substitution.

7 illus, 13 ref

002227   Thomas J;George A V;Thomas V (Chemistry Dep, Mar Ivanios College, Thiruvananthapuram-695 015, Email: vinoythoma@gmail.com) : Sol-gel synthesis and spectroscopic analysis of chromium in sol gel silica. Asian J Chem 2013, 25(12), 6767-70.

Dense chromia-silica glasses have been successfully synthesized by the sol-gel method. Optical absorption and electron spin resonance studies are used to get the insight information about the prepared matrices. As the heat treatment temperature increased, Cr^{3+ → Cr6+ conversion was facilitated, thereby generating Cr5+ ions in the matrix. The amount of Cr5+ and Cr6+ centers can vary depending on the preparation conditions. Racaah parameter (B) of chromium in the octahydral symmetry has been evaluated by using the spectral data. The reduction of Racaah parameter from its free ion value (918 cm-1) reflects the presence of covalent bonding in the matrix. An attempt has been made to explain the nature of chromium on the basis of rule of ratio of radius.}

3 illus, 1 table, 25 ref

002226   Singh D (Centre for Applied Physics, Central Univ of Jharkhand, Ranchi-835 205, Email: dsinghiuac@gmail.com) : Probing of complete and incomplete fusion dynamics in heavy-ion collision. Pramana J Phys 2014, 82(4), 683-96.

Three different types of experiments have been performed to explore the complete and incomplete fusion dynamics in heavy-ion collisions. In this respect, first experiment for the measurement of excitation functions of the evaporation residues produced in the ^{20Ne+165Ho system at projectile energy ranges ≈ 2-8 MeV/nucleon has been done. Measured cumulative and direct cross-sections have been compared with the theoretical model code PACE-2, which takes into account only the complete fusion process. It has been observed that, incomplete fusion fraction is sensitively dependent on projectile energy and mass asymmetry between the projectile and the target systems. Second experiment for measuring the forward recoil range distributions of the evaporation residues produced in the 20Ne+165Ho system at projectile energy ≈8 MeV/nucleon has been done. It has been observed that, some evaporation residues have shown additional peaks in the measured forward recoil range distributions at cumulative thicknesses relatively smaller than the expected range of the residues produced via complete fusion. The results indicate the occurrence of incomplete fusion involving the breakup of 20Ne into 4He+16O and/or 8Be+12C followed by one of the fragments with target nucleus 165Ho. Third experiment for the measurement of spin distribution of the evaporation residues produced in the 16O+124Sn system at projectile energy ≈6 MeV/nucleon, showed that the residues produced as incomplete fusion products associated with fast α and 2α-emission channels observed in the forward cone, are found to be distinctly different from those of the residues produced as complete fusion products. The spin distribution of the evaporation residues also inferred that in incomplete fusion reaction channels input angular momentum (J₀) increases with fusion incompleteness when compared to complete fusion reaction channels. Present observation clearly shows that the production of fast forward α-particles arises from relatively larger angular momentum in the entrance channel leading to peripheral collision.}

6 illus, 25 ref

002225   Santhosh K P (School of Pure and Applied Physics, Kannur Univ, Swami Anandatheertha Campus, Payyanur-670 327, Email: drkpsanthosh@gmail.com) : Decay of heavy and superheavy nuclei. Pramana J Phys 2014, 82(4), 705-15.

Presented on overview and progress of the theoretical works on the isomeric state a decay, a decay fine structure of even-even, even-odd, odd-even and odd-odd nuclei, a study on the feasibility of observing a decay chains from the isotopes of the superheavy nuclei Z = 115 in the range 271 ≤ A ≤ 294 and the isotopes of Z = 117 in the range 270 ≤ A ≤ 301, within the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed half-lives of the favoured and unfavoured a decay of nuclei in the range 67 ≤ Z ≤91 from both the ground state and isomeric state, are in good agreement with the experimental data and the standard deviation of half-life is found to be 0.44. From the a fine structure studies done on various ranges of nuclei, it is evident that, for nearly all the transitions, the theoretical values show good match with the experimental values. This reveals that CPPMDN is successful in explaining the fine structure of even-even, even-odd, odd-even and odd-odd nuclei. Our studies on the a decay of the superheavy nuclei 271-294₁₁₅ and ^{270-301 117 predict 4a chains consistently from 284,285,286115 nudei and 5α chains and 3α chains consistently from 288-291117 and 292117, respectively. We thus hope that these studies on 284-286115 and 288-292117 will be a guide to future experiments.}

3 illus, 21 ref

002224   Sahu R;Kota V K B (Physics Dep, Berhampur Univ, Berhampur-760 007, Email: rankasahu@rediffmail.com) : Deformed shell model studies of spectroscopic properties of <. Pramana J Phys 2014, 82(4), 757-67.

The spectroscopic properties of ^{64Zn and 64Ni are calculated within the framework of the deformed shell model (DSM) based on Hartree-Fock states. GXPF1A interaction in 1f7/2, 2p3/2, 1f5/2 and 2p1/2 space with 40Ca as the core is employed. After ensuring that DSM gives good description of the spectroscopic properties of low-lying levels in these two nuclei considered, nuclear transition matrix elements (NTME) for the neutrinoless positron double beta decay (Ovβ+β+ and Qvβ+ EC) of 64Zn are calculated. The two-neutrino positron double beta decay half-life is also calculated for this nucleus.}

5 illus, 2 tables, 36 ref

002223   Sahu B B;Singh S K;Bhuyan M;Patra S K (Physics Dep, School of Applied Sciences, Kalinga Institute of Industrial Technology, Bhubaneswar-751 024, Email: bbsnou@gmail.com) : Effect of nonlinearity in relativistic nucleon-nucleon potential. Pramana J Phys 2014, 82(4), 637-47.

A simple form for nucleon-nucleon (AW) potential is introduced as an alternative to the popular M3Y form using the relativistic mean field theory (RMFT) with the non-linear terms in a -meson for the first time. In contrast to the M3Y form, the new interaction becomes exactly zero at a finite distance and the expressions are analogous with the M3Y terms. Further, its applicability is examined by the study of proton and cluster radioactivity by folding it with the RMFT-densities of the cluster and daughter nuclei to obtain the optical potential in the region of proton-rich nuclides just above the double magic core ^{100Sn. The results obtained were found comparable with the widely used M3Y NN interactions.}

2 illus, 2 tables, 38 ref

002222   Sahu B (Physics Dep, North Orissa Univ, Baripada-757 003, Email: bd_sahu@yahoo.com) : Comprehensive dacay law for emission of charged particles and exotic cluster radioactivity. Pramana J Phys 2014, 82(4), 717-25.

A general decay formula for the emission of charged particles from metastable nuclei is developed based on the basic phenomenon of resonances occurring in quantum scattering process under Coulomb-nuclear potential. It relates the half-lives of radioactive decays with the Q values of the outgoing elements with masses and charges of the nuclei involved in the decay. The relation is found to be a generalization of the Geiger-Nuttall law in a radioactivity and explains well all the known emissions of charged particles including clusters, alpha and proton.

3 illus, 15 ref

002221   Prasath M;Muthu S (Physics Dep, Aksheyaa College of Engineering, Puludivakkam, Maduranthagam Taluk, Kancheepuram-603 314, Email: muthu@svce.ac.in) : Vibrational assignments, first-order hyperpolarizability and molecular structure of 5-(2-chlorphenyl)-7-nitro-2,3-dihydro-1,4-benzodiazepine-2-one by hartee-fock and density functional theory calculations. Asian J Chem 2013, 25(12), 6771-6.

Vibrational analysis of the 5-(2-chlorphenyl)-7-nitro-2,3-dihydro-1,4-benzodiazepin-2-one (5C7NB2) compound was carried out by using FT-Raman and FT-IR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational frequencies of 5C7NB2 have been investigated by Hartree-Fock (HF) and density functional B3LYP methods with the 6-31G (d,p) basis set. The geometry and normal modes of vibration obtained from the HF and DFT methods are in good agreement with the experimental data. The first order hyperpolarizability (β total) of this novel compound and related properties (β, μ and Δα) are calculated using HF/6-31G (d,p) and B3LYP/6-31G(d,p) methods based on the finite-field approach.

3 illus, 3 tables, 25 ref

002220   Palit R;Saha S (NO, Tata Institute of Fundamental Research, Home Bhabha Road, Mumbai-400 005, Email: palit@tifr.res.in) : Investigation of exotic modes of spinning nuclei near <. Pramana J Phys 2014, 82(4), 649-58.

Recently, a digital data acquisition system with 96 channels has been set up for the Indian National Gamma Array (INGA) consisting of 24 Compton-suppressed clover detectors. The digital system provides higher throughput, better energy resolution and better stability for the mul-tidetector Compton-suppressed clover array compared to the previous conventional system with analog shaping. A number of nuclear spectroscopic experiments have been carried out using the array. Selected results from this array will be presented which highlight different excitations of nuclei near-shell gaps.

6 illus, 41 ref

002219   Pal S;Sadhukhan J (NO, Variable Energy Cyclotron Centre, Salt Lake City, Kolkata-700 064, Email: santanupal1950@gmail.com) : Fission dynamics of hot nuclei. Pramana J Phys 2014, 82(4), 671-82.

Experimental evidence accumulated during the last two decades indicates that the fission of excited heavy nuclei involves a dissipative dynamical process. We shall briefly review the relevant dynamical model, namely the Langevin equations for fission. Statistical model predictions using the Kramers' fission width will also be discussed.

5 illus, 39 ref

002218   Muralithar S (NO, Inter-Univ Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110 067, Email: smuralithar@gmail.com) : Nuclear structure at high spin using multidetector gamma array and ancillary detectors. Pramana J Phys 2014, 82(4), 769-78.

A multidetector gamma array (GDA), for studying nuclear structure was built with ancillary devices namely gamma multiplicity filter and charged particle detector array. This facility was designed for in-beam gamma spectroscopy measurements in fusion evaporation reactions at Inter-University Accelerator Centre, New Delhi. Description of the facility and in-beam performance with two experimental studies done are presented. This array was used in a number of nuclear spectroscopic and reaction investigations.

7 illus, 27 ref

002217   Kundu S (NO, Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata-700 064, Email: samir.kundu@gmail.com ) : Effect of nuclear structure in the emission of reaction products in heavy-ion reactions. Pramana J Phys 2014, 82(4), 727-41.

Study of intermediate mass fragments (IMFs) and light charged particles (LCPs) emission has been carried out for a few reactions involving α-cluster and non-α-cluster systems to see how the emission processes are affected by nuclear clustering. Li, Be, B and α-particles have been studied from α-clustered system ^{16O + 12C for 117, 125, 145 and 160 MeV bombarding energies respectively. The enhanced yields of near-entrance channel fragment B and large quadrupole deformation of the produced composite 28Si* extracted from LCP spectra indicate the survival of orbiting-like process in 16O + 12C system at these energies. The same IMFs emitted from the α-cluster system 12C (77 MeV) + 28Si and nearby non-a cluster 11B (64 MeV) + 28Si and 12C (73 MeV) + 27A1 (all having the same excitation energy of <126>67 MeV) have also been studied. The fully energy damped (fusion-fission) and the partially energy damped (deep inelastic) components of the fragment energy spectra have been extracted. It has been found that the yields of the fully energy damped fragments for all the above reactions are in conformity with the respective statistical model predictions. The time-scales of various deep inelastic fragment emissions have been extracted from the angular distribution data. The angular momentum dissipation in deep inelastic collisions has been estimated from the data and it has been found to be close to the corresponding sticking limit value.}

10 illus, 2 tables, 32 ref

002216   Kota V K B (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: vkbkota@prl.res.in) : Lie algebra symmetries and quantum phase transitions in nuclei. Pramana J Phys 2014, 82(4), 743-55.

In this paper, an overview of some aspects of quantum phase transitions (QPT) in nuclei is given and they are: (i) QPT in interacting boson model (.sdlBM), (ii) QPT in two-level models, (iii) critical point E(5) and X(5) symmetries, (iv) QPT in a simple solvable model with three-body forces. In addition, some open problems are also given.

1 illus, 5 tables, 34 ref

002215   Kim D H;Bae S E;Kim J Y;Park T H;Park Y J; Song K (Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353, Republic of Korea, Email: sebae@kaeri.re.kr) : Solubility measurement of Li₂O in LiCl molten salt for electro-reduction process. Asian J Chem 2013, 25(12), 7055-7.

The change of Li₂O solubility with the concentration of high heat-generating elements such as Cs and Sr was measured in a LiCl melt, which is generally used as an electrolyte medium in an electrolytic reduction step of pyrochemical processing. The change in Li₂O solubility is one of the important parameters in the electrolytic reduction. High temperature filtration using a porous tube and acid-base titration were employed to measure the solubility of Li₂O. The solubility of Li₂O was found to be 8.8 wt. % in pure LiCl molten salt at 650 °C. The solubility slightly increased when SrCl₂ (alkaline earth metal) was added to LiCl. In contrast, the addition of CsCl (alkali metal) significantly decreased the solubility.

5 illus, 19 ref

002214   Kailas S (NO, Bhabha Atomic Research Centre, Mumbai-400 085, Email: swaminathankailas305@gmail.com) : Keynote address: one hundred years of nuclear physics - progress and prospects. Pramana J Phys 2014, 82(4), 619-24.

Nuclear physics research is growing on several fronts, along energy and intensity frontiers, with exotic projectiles and targets. The nuclear physics facilities under construction and those being planned for the future make the prospects for research in this field very bright.

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002213   Jain A K;Joshi B N (Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai-400 085) : Cluster knockout reactions. Pramana J Phys 2014, 82(4), 697-704.

Cluster knockout reactions are expected to reveal the amount of clustering (such as that of α, d and even of heavier clusters such as ^{12C, 16O etc.) in the target nucleus. In simple terms, incident medium high-energy nuclear projectile interacts strongly with the cluster (present in the target nucleus) as if it were existing as a free entity. Theoretically, the relatively softer interactions of the two outgoing particles with the residual nucleus lead to optical distortions and are treated in terms of distorted wave (DW) formalism. The long-range projectile-cluster interaction is accounted for, in terms of the finite range (FR) direct reaction formalism, as against the more commonly adopted zero-range (ZR) distorted wave impulse approximation (DWIA) formalism. Comparison of the DWIA calculations with the observed data provide information about the momentum distribution and the clustering spectroscopic factor of the target nucleus. Interesting results and some recent advancements in the area of (α, 2α) reactions and heavy cluster knockout reactions are discussed. Importance of the finite-range vertex and the final-state interactions are brought out.}

7 illus, 1 table, 24 ref

002212   Ha Y G;Lee S;Park J H;Lee C G;Song K (Nuclear Chemistry Research Division, Korea Atomic Energy Research Institute, 989-111 Daeduk-daero, Yuseong-gu, Daejeon 305-353, Republic of Korea, Email: yha@kaeri.re.kr) : Surface-modified dielectric materials for transistor. Asian J Chem 2013, 25(12), 7051-4.

Organic field-effect transistors operating at low voltage (<60> 2 V) have been fabricated using new solution-processable nanoscale dielectric as the gate dielectric material. In this paper, we demonstrate that a monolayer of octadecyltrichlorosilane on top of nanoscale dielectric shows good improved dielectric properties with optimized changing the surface characteristics and good insulating property with leakage current densities as low as 10^{-7 A/cm2 at 1 V and capacitance value approaching 420 nF/cm2. The corresponding pentacene transistors based on these dielectrics exhibit improved performance with hole mobility of <126> 0.2 cm2/Vs and I_on/I_off ratio <126> 105.}

5 illus, 1 table, 7 ref

002211   Ghorui S K;Praharaj C R (Physics Dep, IIT Ropar, Rupnagar-140 001, Email: surja@iitrpr.ac.in) : Deformed configurations, band structures and spectroscopic properties of N = 50 Ge and Se nuclei. Pramana J Phys 2014, 82(4), 659-69.

The deformed configurations and rotational band structures in N=50 Ge and Se nuclei are studied by deformed Hartree-Fock with quadrupole constraint and angular momentum projection. Apart from the 'almost' spherical HF solution, a well-deformed configuration occurs at low excitation. A deformed well-mixed Ω = l/2^{+ neutron orbit comes down in energy (from the shell above N = 50) to break the N = 50 spherical shell closure. A K = 7- isomer is predicted in 84Se at fairly low excitation energy. At higher excitation energies (8 MeV), a deformed band with Ω = 7/2+-l/2-(based on h_11/2) neutron Ip-lh excitation, for 82Ge and 84Se, is shown in our calculation. Our study gives insight into possible deformed structures at spherical shell closure.}

5 illus, 2 tables, 35 ref

002210   De J N;Samaddar S K;Agrawal B K (Theory Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700 064, Email: jn.de@saha.ac.in) : S-matrix approach to the equation of state of dilute nuclear matter. Pramana J Phys 2014, 82(4), 625-35.

Based on the general analysis of the grand canonical partition function in the S-matrix framework, a method is presented to calculate the equation of state of dilute warm nuclear matter. The result is a model-independent virial series for the pressure and density that systematically includes contributions from all the ground and excited states of all the stable nuclear species and their scattering channels. The multiplicity distribution of these species to keep the matter in statistical equilibrium is found out and then the pressure, incompressibility and the symmetry energy of the system are evaluated. The calculated symmetry energy coefficients are found to be in fair agreement with the recent experimental data.

4 illus, 29 ref

001166   Rao S;Agrawal P (International Institute of Information Technology - Bangalore, , Bangalore-560 100, Email: shrao@ieee.org) : Solar energy for information technology: challenges and possibilities. Curr Sci 2013, 104(1), 22-2.

Information technology (IT) equipment is already estimated to account for about 2% of the global energy consumption, and this figure is only expected to rise. However, the use of solar power for IT is yet to receive the attention it deserves from researchers, and there is a vast array of important problems to be addressed to enable the use of solar and other alternative energy sources in IT. In this note, we take the view that a broad systems perspective of solar power generation and utilization (rather than looking only at component technologies such as PV, solar-thermal, etc.) is essential, and mention major directions which in our opinion merit attention in this regard.

7 ref

001165   Philip, Even John (School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar-751 005, Email: evanphilip@gmail.com) : Analysis of the circular track experiment measuring the one-way speed of light. Curr Sci 2013, 104(5), 582-3.

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001164   Pathak T K;Purohit L P;R Kumar (Physics Dep, Gurukula Kangri Univ, Haridwar, Email: lppurohit@gmail.com) : Comparative study of al doped ZnO powder and thin film fabricated by RF sputtering for transparent conducting window in solar cells. Invertis J renewable Energy 2014, 4(2), 79-82.

ZnO Powder was mixed with 2.5 wt% of Al₂O₃ powder using solid state reaction. This ceramics bulks was used to prepare target of 2 inch diameter for sputtering system. Al doped ZnO (AZO) thin films were synthesized on ITO coated corning glass substrate using RF sputtering. The structural, morphology and optical properties were studied using X-ray diffraction, SEM, UV-VIS-IR spectrophotometer. X-ray diffraction show the crystalline hexagonal wurtzite structure of Al doped ZnO powder and thin film. The crystallite size of AZO powder and film were 64.8 nm & 124.2 nm respectively. The higher transmittance (97%) was observed for AZO powder than that of thin film was (89%). The optical band gap of AZO powder and thin film were 3.24 eV and 3.19 eV respectively. Characterization of the material was done for their optoelectronics properties to be used in solar cells.

6 illus, 1 table, 15 ref

001163   Pal P K;Gupta H;Purohit L P;Rajendra Kumar; Mehra R M (Physics Dep, Gurukula Kangri Univ, Haridwar-249 401) : Dark and photoconductivity in a Se-Te-Pb thin films. Invertis J renewable Energy 2014, 4(2), 111-4.

Temperature dependence of conductivity is studied in a dark as well as in presence of light in amorphous thin films of Se₇₀Te_30-x Pb_x (x = 0, 2, 6, 8) prepared by vacuum evaporation technique. Dark and Photoconductivity measurements were carried out on these films were characterized over the temperature range 250-350 K. The activation energy of photoconduction is found to decrease with increasing light intensity, which indicates illumination causes a shift in the Fermi level due to splitting of the Fermi level into quasi Fermi levels.

4 illus, 1 table, 12 ref

001162   Mamta Rani;Jagdish Kaur;Tripathi S K (Centre of Advanced Study of Physics, Physics Dep, Panjab Univ, Chandigarh-160 014, Email: surya@pu.ac.in) : Comparative study of organic dyes adsorbed in ZnO for photovoltaic applications. Invertis J renewable Energy 2014, 4(2), 93-6.

If the material is sensitized with the appropriate molecules, it becomes interesting for an electrode material for solar energy conversion in dye sensitized solar cells, various sensor application i.e. gas sensors and biosensors or in photocatalytic applications. In the present work, the nanostructured dye adsorbed ZnO (ZnO/dye) films prepared by doctor blade method have been investigated in conductivity and photoconductivity measurements in view of applications in dyesensitized solar cells (DSSC) and in optoelectronics, since electron transport in these devices plays a decisive role for the electron collection efficiency and therefore for the overall efficiency. Dyes of two different colors have been chosen for film preparation: Acridine orange (AO) and Fast Green (FCF). All the dyes and electrodes are examined for their absorbance in the visible region. Pure ZnO films are prepared and investigated for comparison. After the dye is adsorbed on the ZnO electrode, absorption spectra of FCF sensitized film broadened in visible region slightly with a red shift in the peak position compared to the absorbance spectra in ethanol. Highly porous ZnO films are found to have high dark conductivity, probably because of a higher n-doping, which is due to a higher concentration of Zn atoms in the film. On the other hand, dye sensitized films are found to show higher sensitivity to illumination with visible light in photoconductivity measurements due to a higher absolute photoconductivity and lower conductivity in the dark. It can be seen that the photosensitivity for ZnO/FGF is higher than that for the ZnO/AO film.

5 illus, 1 table, 19 ref

001161   Kaushal P;xsSubhash Chand (Physics Dep, National Institute of Technology, Hamirpur-177 005, Email: priyankanit84@gmail.com) : Effect of patch size on current-voltage characteristics of inhomogeneous schottky diodes with discrete distribution of barrier height patches. Invertis J renewable Energy 2014, 4(2), 97-100.

The Poisson's equation and the drift diffusion equations have been used to simulate the current-voltage characteristics of inhomogeneous Schottky diodes with discrete distribution of barrier height patches of varying size. The potential variation inside the bulk semiconductor near the metal-semiconductor contact is calculated and then the current as a function of bias through the Schottky diode for various patch sizes - 35 - are calculated. From the simulated current-voltage characteristics the diode parameters were extracted by fitting of current-voltage data into thermionic emission diffusion current equation. The derived barrier parameters are analyzed to study the effect of different barrier patch size on the current-voltage characteristics of inhomogeneities Schottky diodes.

6 illus, 10 ref

001160   Kadash E A;AL Hattami A A;Rathod J R;Patel K D;Pathak V M (Physics Dep, Hodeidah University, Hodeidah City, Republic of Yemen, Email: Ebtesam2080@yahoo.) : Synthesis and characterization of cadmium sulfide crystals grown by DVT technique. Int J pure appl Sci Technol 2014, 22(1), 18-26.

Cadmium Sulfide crystals were grown by direct vapor transport (DVT) from high-purity tarting materials. The grown CdS crystals were orange in color, transparent, dendrite platelets shaped were observed. The structure of CdS crystals has been studied with thehelp of X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). The crystals grown by DVT technique possess hexagonal structure. The morphology of the surface of the grown crystals was studied by the optical micrograph and the Scanning Electron Microscopy (SEM). The direct energy bandgap has been estimated from the absorption coefficient values using Tauc's procedure which is found to be 2.37 eV.

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001159   Jagdish Kaur;Mamta Rani;Tripathi S K (Centre of Advanced Study in Physics, Physics Dep, Panjab Univ, Chandigarh-160 014, Email: surya@pu.ac.in) : Determination of optical constants of annealed sn doped cdse thin films prepared by thermal evaporation technique. Invertis J renewable Energy 2014, 4(2), 74-8.

Thin films of CdSe doped with 1 at. wt. % tin are prepared by thermal vacuum evaporation technique on glass substrates at room temperature. The prepared film is annealed in vacuum at 130 °C, and characterized by the transmission spectra. The transmission spectra are recorded in the transmission range 400-3300 nm. Transmittance measurements are used to calculate the refractive index (n) and absorption coefficient (α) using Swanepoel's method. The optical constants such as extinction coefficient (k), real (ε₁) and imaginary (ε₂) dielectric constants, dissipation loss (tan δ), optical conductivity (σ_opt) are also calculated for Sn doped CdSe thin films.

6 illus, 25 ref

001158   Gupta H;Purohit L P;Pal P K;R Kumar;Ajendra Kumar;Gill F S;Mehra R M (Physics Dep, Gurukula Kangri Univ, Haridwar, Uttarakhand) : Electronic transport in Se-doped A-Si:H under annealing. Invertis J renewable Energy 2014, 4(2), 69-73.

In the present work, the effect of annealing on dark and photoconductivity of Se-doped amorphous hydrogenated silicon films (a-Si:H) prepared by PECVD method have been investigated. The variation of the dark conductivity and photoconductivity as a function of temperature have been carried out on unannealed and annealed thin film samples at different annealing temperatures (T_a) from 100°C to 500°C. It was found that the values of both dark and - 34 - photo conductivity vary with doping concentration as well as annealing temperature. The activation energy was calculated from dependence of dark conductivity measured after the samples were annealed at different temperatures. The variation of photoconductivity with annealing temperature for the Se-doped a-Si:H films was also investigated under optimised annealing temperature.

4 illus, 1 table, 24 ref

001157   El-Gamal H;Abd El-Mageed A I (Physics Dep, Faculty of Sciences, Assiut University, Assiut-71516, Egypt, , Email: hanyelgamal2000@yahoo.com) : Natural radioactivity in water samples from Assiut City, Egypt. Int J pure appl Sci Technol 2014, 22(1), 44-52.

Activity concentrations of ^{226Ra, 232Th and 40K were determined in water samples. The radioactivity concentrations of 226Ra, 232Th, and 40K showed large variations, so the results were classified into two groups (A and B) to facilitate the interpretation of the results. Group A represents samples collected from different locations in Assiut and characterized by low activity concentrations with average values of 0.20, 0.13 and 5.29 Bql-1 for 226Ra, 232Th, and 40K, respectively. Group B represents samples mainly collected from the area around Assiut Thermal Power Plant and characterized by very high activity concentrations with average values of 7.68±3.91, 8.07±0.74, and 27.20±1.79 Bql-1 for 226Ra, 232Th, and 40K, respectively. As far as the measured gamma radionuclides is concerned, the mean annual effective doses for analyzed samples of group A are in the range of 0.02-0.08, 0.03-0.17 and 0.03-0.10 mSv yr-1 for infants, children and adults, respectively, all being lower than the reference level of the committed effective dose recommended by the WHO, while the mean annual effective doses calculated for samples of group B, all being higher than the reference level of the committed effective dose recommended by the WHO.}

2 illus, 3 tables, 31 ref

001156   Choithrani R (Physics Dep, Barkatullah Univ, Bhopal-462 026, Email: renuchoithrani@gmail.com) : Specific heat and elastic properties of someconducting stannate perovskite material. Invertis J renewable Energy 2014, 4(2), 107-10.

Specific heat and elastic properties of BaSnO₃ have been investigated for the first time using extended rigid ion model (ERIM). The investigations include the computation of the cohesive energy, Reststrahlen frequency, Debye temperature, Gruneisen parameter, tolerance factor, elastic constants, bulk modulus, shear modulus, Young's modulus and specific heat of BaSnO₃. Barium stannate (BaSnO₃) exhibits cubic perovskite-like structure, behaves as a semiconductor with a gap of 3.4 eV and stable at high temperatures up to 1273 K. We have found that the elastic constants are in good correlation with the bonding properties. The results have been found to present an overall better interpretation of the available experimental data as compared to those obtained from other theoretical model calculations.

2 illus, 16 ref

000118   Vaitheeswaran G;Ramesh Babu K;Yedukondalu N; Appalakondaiah S (Advanced Centre of Research in High Energy Materials, Hyderabad Univ, Prof. C. R. Rao Road, Gachibowli, Hyderabad-500 046) : Structural properties of soid energetic materials: a van der Waals density functional study. Curr Sci 2014, 106(9), 1219-23.

In the present work we; have focused our attention towards the complete description of structural properties of energetic solids, namely inorganic azides, secondary explosives and oxidizers through density functional theory-based calculations. We find large deviations in structural parameters calculated with the standard exchange-correlation functional such as local density approximation and generalized gradient approximation (GGA). On the other hand, dispersion-corrected density functional of (GGA + G06) describes the crystal structure of the energetic solids with good accuracy. This leads to the fact that the dispersion-corrected density functionals are essential to describe the crystal structure and thereby the related physical and chemical properties of the energetic solids.

2 illus, 3 tables, 37 ref

000117   Babu V S;Geetha Ramkumar (Space Physics Laboratory, Vikram Sarabhai Space Centre, ISRO-Dep of Space, Thiruvananthapuram-695 022, Email: veenasbabu@gmail.com) : Planetary waves - major forcing agent in generating stratospheric and mesospheric quasi biennial oscillation. Curr Sci 2014, 106(9), 1260-9.

Quasi Biennial Oscillation (QBO) and Semi Annual Oscillation (SAO) are dominant natural oscillations in the equatorial lower stratosphere and mesosphere and are believed to be generated by the wave-mean flow interaction. The characteristics of stratospheric QBO (SQBO) and mesospheric QBO (MQBO) and SAO are studied by making use of the monthly mean zonal and meridional winds derived from four decades of balloon (1970-2010) and rocket (1971-2007) flights and seven years of SKiYMET meteor radar (2004-2011) observations over an equatorial station Thiruvanan-thapuram. The year-to-year variation and interrelationships between these oscillations are also studied. The quantitative estimation of forcing towards the mean flow acceleration producing the maximum phase of SQBO during the four-decade period shows 70-80% contribution from planetary waves, while during minimum phase of SQBO the contribution is 30-35%. It is also found that the contribution by planetary waves towards the mean flow acceleration producing MQBO maximum during the seven-year period is around 30-90% and during MQBO minimum phase it is 30-60%. The vertical structure of these oscillations present over the equatorial station is also derived.

7 illus, 39 ref

024365   Zendehnam A;Mirzaee M;Miri S (Thin Film Laboratory, Physics Dep, Faculty of Science, Arak Univ, Arak 38156-8-8349, Iran, Email: A-Zendehnam@araku.ac.ir) : Influence of deposition rate on PL spectrum and surface morphology of ZnO nanolayers deposited on Si (100) substrate. Bull Mater Sci 2014, 37(2), 179-83.

Zinc oxide (ZnO) thin films were deposited on Si (100) substrate through sputtering of zinc by DC magnetron, followed by thermal oxidation. Different deposition rates were used in coating films with 100 nm thickness (0-6-4-5 nm/s). Photoluminescence spectra of the produced samples were obtained and it was found that the violet emission peak intensity increases with deposition rate. Scanning electron microscopy (SEM) micrograph and atomic force microscopy (AFM) images for the zinc oxide films were obtained. Morphological changes due to various deposition rate are discussed in the light of changes observed in the ZnO crystals. Low coating rates produced smooth surface with small grains while higher deposition rates increased the surface roughness and larger grain size. AFM and SEM results are in good agreement and support the PL results.

7 illus, 2 tables, 20 ref

024364   Yildirim M;Gokcen M (Physics Dep, Faculty of Arts & Science, Duzce Univ, 81620 Duzce, Turkey, Email: muharremgokcen@duzce.edu.tr) : Comparative study regarding effects of interfacial ferroelectric Bi₄Ti₃O₁₂ (BTO) layer on electrical characteristics of Au/n-Si structures. Bull Mater Sci 2014, 37(2), 257-62.

Present study focuses on the effects of interfacial ferroelectric BTO - 35 - layer on the electrical characteristics of Au/n-Si structures, hence Au/n-Si (MS) and Au/BTO/n-Si (MFS) structures were fabricated and admittance measurements (capacitance-voltage: C-V and conductance-voltage: G/ ω-V) of both structures were conducted between 10 kHz and 1 MHz at room temperature. Results showed that C-V and G/ω-V characteristics were affected not only by frequency but also through deposition of BTO layer. Some effects can be listed as sharper peaks in C-V plots, higher capacitance and conductance values. Structure's series resistance (R_s) also decreased due to BTO layer. Interface states (N_ss) profiles of the structures were obtained using Hill-Coleman and high-low frequency capacitance (C_HF-C_LF). Some of the main electrical parameters were extracted from C^{-2 -V plots using depletion capacitance approach. Furthermore, current-voltage characteristics of MS and MFS structures were presented.}

7 illus, 2 tables, 28 ref

024363   Trivedi C M;Rana V A (Physics Dep, School of Sciences, Gujarat Univ, Ahmedabad, Email: ranava2001@yahoo.com) : Static permittivity, refractive index, density and related properties of binary mixtures of pyridine and 1-propanol at different temperatures. Indian J pure appl Phys 2014, 52(3), 183-91.

Static permittivity and permittivity at optical frequency of pyridine, 1-propanol and their binary mixtures at nine different concentrations have been measured at 303, 313 and 323 K temperatures. The investigation of binary mixtures showed a systematic change in permittivity with change in concentration of 1-propanol in the binary mixture. Measured properties of these mixtures were used to calculate Kirkwood correlation factor and excess permittivity. Determined parameters have been interpreted in terms of molecular interaction among the molecular species of the binary mixtures. Binary mixture data of static permittivity and refractive index are compared with the predicted values of static permittivity and refractive index using various mixing rules. Comparison of various mixing rules has been expressed in terms of root mean square deviation (RMSD).

6 illus, 8 tables, 44 ref

024362   Singh V P;Badiger N M;Medhat M E (Physics Dep, Karnatak Univ, Dharwad-580 003, Email: kudphyvps@rediffmail.com) : Comprehensive study on energy abdorption build-up factors and exposure build-up factors of solid state nuclear track detectors. Indian J pure appl Phys 2014, 52(5), 314-21.

The gamma-ray build-up factors of solid state nuclear track detectors (SSNTDs) have been computed for photon energy in the range 0.015-15 MeV up to 40 mfp penetration depth by geometrical progression (GP) method. Significant variations in energy absorption build-up factors (EABFs) and exposure build-up factors (EBFs) for the investigated SSNTDs are observed. The EABFs and EBFs of the SSNTDs are strongly dependent upon the photon energy, penetration depths and the chemical compositions. The build-up factors are small in low and high photon energy whereas very large in medium energy region. The result could be useful in the field of radiation dosimetry of solid state nuclear track detectors for gamma dose measurements.

3 illus, 3 tables, 44 ref

024361   Sharma S K;Im H;Kim D Y;Mehra R M (Semiconductor Science Dep, Dongguk Seoul Univ, Jung-gu, Seoul-100 715, Republic of Korea, Email: sksharma@dongguk.edu) : Review on Se- and S-doped hydrogenated amorphous silicon thin films. Indian J pure appl Phys 2014, 52(5), 293-313.

Hydrogenated amorphous silicon thin films manufactured by plasma deposition techniques are widely used in electronic and optoelectronic devices. The optical and electrical properties of undoped and doped hydrogenated amorphous silicon (a-Si:H) thin films - 34 - determine the importance and characteristics of the final film structure of practical devices. In particular, a-Si:H thin film solar cells and optical sensors have many industrial and technical advantages, such as being light weight, low cost, and having a large deposition area. The a-Si:H thin film is one of the candidates for flexible solar cells for use in space. This article reviews the optical and electrical properties of double donor Se-and S-doped a-Si:H thin films, which can be considered as an alternative to wide bandgap absorbing layers in the next generation of optoelectronic devices.

^iia12 illus, 4 tables, 236 ref

024360   Shanker J;Singh P K;Singh M P (Physics Dep, Institute of Basic Sciences, Dr B R Ambedkar Univ, Khandari Campus, Agra-282 002, Email: singhpk77@gmail.com) : Isothermal and adiabatic extrapolations of thermoelastic properties to extreme compression. Indian J pure appl Phys 2014, 52(5), 337-40.

The extreme compression limits of thermal expansivity, isothermal bulk modulus, adiabatic bulk modulus and products of thermal expansivity and bulk modulus have been obtained using the basic principles of calculus and some thermodynamic identities in terms of the Anderson-Grneisen parameters and pressure derivatives of bulk modulus. The isothermal extrapolations are found to be different from the corresponding adiabatic extrapolations. The results have been obtained using the Stacey thermodynamics of materials at infinite pressure.

10 ref

024359   Saxena K;Amit Kumar;Malik N;Pramod Kumar;Jain V K (NO, Amity Institute of Advanced Research and Studies (Materials and Device, Noida-201 303, Email: saxena.mehta@gmail.com) : Ultraviolet sensing properties of polyvinyl alcohol-coated aluminium-doped zinc oxide nanorods. Bull Mater Sci 2014, 37(2), 295-300.

Undoped and aluminium (Al)-doped zinc oxide (ZnO) nanorods have been synthesized by electrochemical route. The synthesized materials have been characterized by X-ray diffraction, UV-visible spectrometer and scanning electron microscope. The Al-doped ZnO nanorods have been coated with polyvinyl alcohol. Current-voltage characteristics have been investigated in dark and under UV-light illumination. Aluminium doping in ZnO increase its electrical conductivity and further polyvinyl alcohol coating on Al-doped ZnO increase UV sensitivity of the material. Response and recovery time of Al-doped ZnO and PVA-coated Al-doped ZnO nanorods have been recorded. PVA-coated Al-doped ZnO nanorods shows very fast response and recovery time of 10 s in comparison to uncoated ZnO (20 min) nanorods.

6 illus, 41 ref

024358   Saini P;Arora M;Arya S K;Tawale J S (NO, CSIR-National Physical Laboratory, Dr K S Krishnan Road, New Delhi-110 012, Email: pksaini@nplindia.org) : Effect of controlled doping on electrical properties and permittivity of PTSA doped polyanilines and their EMI shielding performance. Indian J pure appl Phys 2014, 52(3), 175-82.

Emeraldine base (EB) has been protonated with different concentration of para-toluene sulfonic acid (PTSA) to form doped polyanilines (PANIs). These samples have been characterized by various techniques and a detailed correlation between dopant concentration and structural, thermal, electrical and electromagnetic properties has been established. The FTIR/UV-Visible and EPR spectra confirm the formation of polarons as proto-generated charge carriers whose concentration follows the dopant concentration trend. It was also observed that increase in doping level leads to systematic improvement of electrical conductivity (1.2 x 1^{-9 to 5.3 S/cm) as well as complex - 33 - permittivity (ε' <126>5.5 & ε" <126>0.6 to ε' <126>22.3 & ε" <126>24.6) with parallel improvement of electromagnetic (EM) radiation blocking capacity from -3.8 dB (for EB) to -23.9 dB (for 1.0 M PTSA doped sample). Further, the attenuation was found to be critically dependent on dopant concentration, complex permittivity and electrical conductivity revealing that both polarization as well as conduction is important for achieving high attenuation. It was also observed that reflection is main phenomenon at low doping level whereas absorption becomes increasingly important at higher doping levels and extends dominant contribution towards total attenuation.}

6 illus, 2 tables, 36 ref

024357   Rawat A;Mahavar H K;Tanwar A;Singh P J (Physics Dep, M S J College, Bharatpur-321 001, Email: anandrawat15oct@gmail.com) : Electrical properties of polyvinylpyrrolidone/polyacrylamide blend thin films. Bull Mater Sci 2014, 37(2), 273-9.

Electrical properties of polyvinylpyrrolidone, polyacrylamide and their blend thin films have been investigated as a function of temperature and frequency. The films were prepared using solution casting method and the measurements on films were carried out at different temperatures ranging from 305 to 345 K covering a frequency range from 10^{2 to 105 Hz. The conductivity of film samples was found to increase upon increasing the temperature. Lowering of activation energy by increasing the polyvinylpyrrolidone percentage may be due to the predominance of ion conduction mechanism caused by polyvinylpyrrolidone in the blend. The permittivity (ε_r) and dielectric loss (ej) were found to decrease upon increasing frequency. Temperature and frequency dependence of impedance, relaxation time and electric modulus of thin film samples have also been studied. From electric modulus formalism, polarization and conduction relaxation behaviour in the film samples have been discussed.}

10 illus, 3 tables, 33 ref

024356   Pandey D K;Singh D;Bhalla V;Tripathi S;Yadav R R (Physics Dep, P P N College, Kanpur-208 001, Email: dsingh13@amity.edu) : Temperature dependent elastic and ultrasonic properties of ytterbium monopnictides. Indian J pure appl Phys 2014, 52(5), 330-6.

Ultrasonic properties of ytterbium monopnictides (YbX: X= As, P) have been evaluated along <100>, <110> and <111> directions in the temperature range 100-400 K. The second-and third-order elastic constants (SOECs and TOECs) are calculated for the computation of ultrasonic parameters. Other elastic constants like bulk modulus, shear modulus, Young's modulus, Poisson ratio, anisotropic ratio, tetragonal moduli and fracture/toughness ratio are also calculated to evaluate the performance of materials under investigation. The elastic behaviour of these materials shows their brittle nature. It is found that the ultrasonic attenuation in ytterbium monopnictides increases with temperature and have quadratic function of temperature. The nature of ultrasonic attenuation was found to be quite similar to the other observed results of rare-earth monopnictides.

4 illus, 4 tables, 41 ref

024355   Mustafa M;Beigh M R (Electronics & Instrumentation Technology Dep, Kashmir Univ, Kashmir, Email: mrbku@yahoo.com) : Novel linear feedback shift register design in quantum-dot cellular automata. Indian J pure appl Phys 2014, 52(3), 203-9.

Quantum-dot Cellular Automata (QCA) is one of the candidates among future nanoelectronic computing technologies. QCA is based on cells of coupled quantum dots. The QCA cells have features on the very low nanometer scale, much smaller than the present state of art size of the smallest transistor. The physical interaction between neighbouring cells has been exploited in the implementation of logic functions. This paper reviews the basic paradigm of QCA and presents efficient design and layout of a novel linear feedback shift register (LFSR) with minimum complexity and cell count. The proposed LFSR can be effectively used to design more complex circuits like scramblers and pseudo random pattern generators. The proposed design was verified by carrying out simulation using the QCADesigner tool. These implementations and simulations are useful for building more complex digital communication based circuits in QCA.

13 illus, 31 ref

024354   Manikandan K;Mani P;Fermi Hilbert Inbaraj P; Dominic Joseph T;Thangaraj V;Surendra Dilip C;Joseph Prince J (Physics Dep, College of Engineering Univ, Anna Univ, BIT Campus, Tiruchirappalli-620 024, Email: 1984manikandan@gmail.com) : Effect of molar concentration on structural, morphological and optical properties of CdS thin films obtained by SILAR method. Indian J pure appl Phys 2014, 52(5), 354-9.

Thin films of cadmium sulphide (CdS) were deposited on a glass plate by the SILAR method for 0.05, 0.10 and 0.15 M concentrations. The structural, optical and morphological properties of the films were characterized by X-ray diffraction (XRD), energy dispersive spectrum (EDS), UV-Vis spectrometry and atomic force microscopy (AFM) techniques. The XRD patterns of the films indicated that the crystalline natured films have hexagonal phases. The energy-dispersive spectrum (EDS) analysis confirms the compositions of cadmium and sulphur in CdS films. The direct band gap values in the range 2.32-2.24 eV were observed from the transmittance studies, the results infer that the band gap energy decreases with increasing molar concentration. The AFM studies show that the film is evenly coated and has uniform grain sizes.

9 illus, 3 tables, 37 ref

024353   Mahdi M A;Hassan J J;Kasim S J;Ng S S;Hassan Z (Nano-Optoelectronics Research and Technology Laboratory (N.O.R.), School of Physics, Sains Malaysia Univ, 11800 Penang, Malaysia, Email: mazinauny74@yahoo.com) : Solvothermal growth of single-crystal CdS nanowires. Bull Mater Sci 2014, 37(2), 337-45.

Cadmium sulfide (CdS) nanowires (NWs) were prepared by the solvothermal method using ethylenedi-amine as a solvent. Two sets of CdS NWs were synthesized at 160 and 200 °C for various reaction durations (3.5, 7 and 24 h). Scanning/tunneling electron microscopy was used to examine the surface morphology of the grown NWs. Their dimensions are found to depend on the reaction temperature and duration. The CdS NWs grown at 200 °C for all durations are longer than those - 31 - prepared at 160 °C, with diameters ranging from 15 to 40 nm. A three-armed structure is exhibited by all the samples. The grown CdS NWs display a hexagonal wurtzite phase and grows along the (001) direction. The optical absorption of the grown NWs shows a sharp absorption edge with a blueshift, which indicates an expansion of the optical band gap. All prepared samples show two emission peaks in their pho-toluminescence spectra. The emission peak location depends on the reaction temperature and duration. The CdS NWs prepared at 160 °C show a sharp band-band emission compared with those prepared at 200 °C. Raman analysis indicates that the optical properties of the grown NWs are enhanced with increased temperature and reaction duration.

8 illus, 2 tables, 39 ref

024352   Lawrence M B;Desa J A E;Aswal V K;Rai R (Physics Dep, Goa Univ, Taleigao Plateau, Goa-403 206, Email: erwindesa@gmail.com) : Properties of poly(vinyl alcohol)-borax gel doped with neodymium and praseodymium. Bull Mater Sci 2014, 37(2), 301-7.

Neodymium and praseodymium ions, singly and in combination, have been doped into a poly(vinyl alcohol)-borax matrix. X-ray diffraction shows structural correlations from 2 to 6 A and 15 A, while small angle neutron scattering indicates that the rare-earth ions do not affect the nanoscale structures of the gels. Differential scanning calorimetry shows the glass transition temperature to increase with concentration of Pr in the gel. Excitation in the ultraviolet region leads to luminescent emission in the visible region. Simultaneous absorption in the visible region then leads to luminescent emission in the near infra-red region. The spectral qualities of the emission bands can be varied by choosing appropriate relative ratios of rare-earth species.

16 illus, 1 table, 17 ref

024351   Khan S U D;Ahmed B;Raghuvanshi S K;Wahab M A (Physics Dep, Jamia Millia Islamia, New Delhi-110 025, Email: skhanphysics@gmail.com) : Structural, morphological and optical properties of silver doped polyvinylpyrrolidone composites. Indian J pure appl Phys 2014, 52(3), 192-7.

Polyvinylpyrrolidone (PVP) doped with different silver concentration (Ag: PVP) composites were prepared by simple solution casting technique using PVP and silver nitrate. The structural, morphological and optical properties of these as grown composites were characterized by powdered X-ray diffraction, SEM, FTIR and UV-VIS techniques. XRD patterns confirm the incorporation of Ag particles in PVP matrix and indicate the improvement in polycrystalline behaviour by the appearance of more diffraction peaks with increased intensity on increasing AgNO₃ concentration in the composites. SEM images reveal the uniform dispersion and increased densification of Ag particles in PVP matrix. Infrared transmission spectra recorded in 4000-400 cm^{-1 region show the characteristic peaks of PVP bonding groups with the minor shift in their position due to Ag doping. UV-VIS spectroscopy results reflected that absorption increases in asymmetric manner and the absorption peak showed red shift with increasing dopant concentration. These results showed that the simple synthesis process can be used for the preparation of such composites suitable for various practical applications.}

7 illus, 1 table, 27 ref