004102   Ramaswamy V;Rajkumar P;Ponnusamy V (Dep of Phys, Annamalai Univ, Annamalai nagar-608 002, Email: srsaranram@rediffmail.com) : FTIR spectroscopic analysis and mineralogical characterization of vellar river sediments. Bull pure appl Sci-Sect D 2006, 25(1), 49-55.

Twenty seven sediment samples were collected from different locations of Vellar river, Tamilnadu starting from Kalrayan hills to Porto-Novo covering a length 200 km. Fourier transform infrared spectroscopic technique has been used to identify the minerals present in the sediments. The minerals such as quartz, feldspar in different structures and kaolinite were present as major minerals, polygorskitc, calcite, aragonite and montmorillonite as minor and cerrussite, smectite and magnesium oxalate as trace minerals. The crystalline nature of quartz was determined from crystallinity index. The relative distribution of quartz, feldspar and kaolinite were determined by calculating extinction co-efficient.

2 illus, 2 tables, 13 ref

004101   Navin Chand;Jain D;Nigrawal A (NO, Regional Res Lab (CSIR), Bhopal-462 026, Email: navinchand15@indiainfo.com) : Investigations on gradient a.c. conductivity characteristics of bamboo (Dendrocalamus strictus). Bull Mater Sci 2006, 29(2), 193-6.

Effect of temperature and frequency variation on a.c. conductivity of bamboo was determined by using a 4274 A Multi-Frequencies LCR meter. Electrical measurements were carried out in the temperature range 24-120°C and in the frequency range 4-100 kHz. It was observed that the a.c. conductivity increased initially and then decreased with increase of temperature and frequencies. The increase of distance from outer surface to the inner surface side increased the a.c. conductivity values and showed the grading in a.c. conductivity behaviour. Two phases of a.c. conductivity behaviour with temperature exist in bamboo. At 10 mm distance a.c. conductivity suddenly increases which is the critical depth from skin for this bamboo. Increase of temperature, at all the frequencies increases the a.c. conductivity initially and then decreases. Downward peaks in a.c. conductivities are observed at all the frequencies due to the presence of moisture in bamboo, which liberated on heating. Sharp peak is observed in case of sample 4, which is inner most strip. Maximum sharp peak is observed at lowest 4 kHz frequency.

5 illus, 10 ref

004100   Murthy C R K;Chandra Lingam S (Dept of Phys, Kakatiya Univ, Warangal-506 009) : K-shell atomic photo effect cross sections at k-edge energies in medium z-elements. Bull pure appl Sci-Sect D 2006, 25(1), 37-40.

The K-Shell atomic photo effect cross sections at K-edge energies of the elements Ag, Cd, In and Sn were obtained by plotting the measured total atomic photo effect cross sections as a function of energy on a log - log scale. The values are compared with the theoretical data of Scofield and an agreement with in the experimental error is obtained, an extensive comparison with earlier experimental data were presented.

1 illus, 1 table, 8 ref

004099   Madhukumar K;Rajendra Babu K;Ajith Prasad K C;James J;Elias T S;Padmanabhan V;Nair C M K (Dep of Phys, Mahatama Gandhi Coll, Thiruvananthapuram-695 019, Email: madhusandh@yahoo.co.in) : Thermoluminescence dosimetry of rare earth doped calcium aluminate phosphors. Bull Mater Sci 2006, 29(2), 119-22.

Thermoluminescence (TL) properties of calcium aluminate (CaAl₂O₄) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications has been discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of radiation doses. Dopant concentration of 0.25 mol% cerium gives maximum TL emission. The well-defined single peak observed at 295°C can be advantageously used for high temperature dosimetry applications.

6 illus, 3 tables, 10 ref

004098   Lo C Y (NO, Appl and Pure Res Inst, 17-Newcastle Drive, Nashua, NH 03060, USA) : Misinterpretation of E=mc2 and einstein's theory of general relativity. Bull pure appl Sci-Sect D 2006, 25(1), 41-7.

Currently, the famous formula E = mc² is often misinterpreted as the unconditional equivalence between inertial mass and each type of energy (i.e., m = E/c²). It is shown that, according to Einstein's general relativity, such a claim is incorrect. The root of this problem is due to an inadequate understanding of special relativity that produced the famous equation E = mc² that, as Einstein clarified, must be understood in terms of energy conservation. For example, the Reissner-Nordstrom metric illustrated that electromagnetic energy and mass are different in terms of gravity. However, this non-equivalence is actually independent of general relativity. Concurrently, it is pointed out that this error is a problem in Will's book, Theory and experiment in gravitational physics."

24 ref

004097   Kumararaman S;Prakash J T J (Deptt of Phys, Nehru Memorial Coll, Puthanampattai, Thuraiyar, Tamil Nadu, Email: armyjpr@yahoo.co.in) : Crystal growth and characterization of ADP (NH₄H₂PO₄) & KDP (K₂H₂PO₄). Bull pure appl Sci-Sect D 2006, 25(1), 31-6.

ADP, KDP crystals are good second harmonic generators ( SHG ) having appreciable non linear optic ( NLO ) properties. Good quality single crystals with size 10 x 8 x 6 mm³ were grown by slow evaporation technique with in 21 days with approximate growth rate of 5mm/day. The grown crystals have been subjected to single crystal x-ray diffraction to determine the unit cell dimensions and morphology. FTIR anaylsers explain the inclusion of the metallic impurities. Which extends the transmission region visibility. The uv-vis spectrum shows that the material has wide optical transparency in the entire visible region. The microhardness test was carried out and the load dependent hardness was measured.

9 illus, 9 ref

004096   Kamila J;Roy S;Bhattacharjee K;Rout B;Dev B N;Guico R;Wang J;Haberl A W;Ayyub P;Satyam P V (Dep of Phys, B.J.B. Junior Coll, Bhubaneswar-751 014, Email: satyam@iopb.res.in) : Proton microbeam irradiation effects on PtBA polymer. Bull Mater Sci 2006, 29(2), 101-5.

Proton beam lithography has made it possible to make various types of 3D-structures in polymers. Usually PMMA, SU-8, PS polymers have been used as resist materials for lithographic purpose. Microbeam irradiation effects on poly-tert-butyl-acrylate (PtBA) polymer using 2.0 MeV proton microbeam are reported. Preliminary results on pattern formation on PtBA are carried out as a function of fluence. After writing the pattern, a thin layer of Ge is deposited. Distribution of Ge in pristine and ion beam patterned surface of PtBA polymer is studied using the optical and secondary electron microscopic experimental methods.

4 illus, 25 ref

003164   Verma P K;Sinha M K (Department of Physics, B.R. Ambedkar Bihar University, Muzaffarpur-842 001) : Scattering of positron by hydrogen like ion. Indian J Phys 2006, 80(2), 205-8.

Scattering of positron by hydrogen-like ion He+ has been theoretically analysed by employing distorted wave method. Total cross section and differential cross sections for 1s-2s excitation of He+ by positron-impact, have been evaluated in intermediate and high enrgy ranges. Differential cross sections have been calculated with polarization potential and without polarization potential to observe the impect of polarixation potential on differential cross section. Phase shifts for e+ -He+ elastic scattering have been calculated. Results have been compared with available theoretical results.

2 illus, 1 table, 7 ref

003163   Tiwari V K;Kimothi A;Bhatnagar D;Saini J S; Saxena V K;Kumar P (Department of Microwave Lab, University of Rajasthan, Jaipur-302 004) : Theoretical and experimental investigations of circular sector microstrip antenna. Indian J Radio Space Phys 2006, 35(3), 206-11.

An analysis of a general circular sector microstrip antenna (CSMA) with sector angle, α is presented. The theoretical analysis is carried out by applying cavity model-based modal expansion technique. The computed results are validated with measured results for CSMA geometry with α = 60°. The computed results show a fairly good agreement with measured results. A reasonably small deviation of 1.06% in the resonant frequency is recorded, while a fairly good agreement between measured and computed return loss and radiation patterns is recorded. This validates the proposed technique of treating CSMA geometry.

5 illus, 13 tables, 11 ref

003162   Thiruvikraman P K (Physics Group, Birla Institute of Technology & Science, Pilani-333 031, Email: vikram@bits_pilani.ac.in) : Rings, chains and planes: variation of Tg with composition in chalcogenide glasses. Bull Mater Sci 2006, 29(4), 371-4.

A microscopic, phenomenological model for the decrease in the viscosity observed at glass transition has been proposed. Model is primarily applicable to chalcogenide glasses. According to this model, the decrease in the viscosity at glass transition is mainly due to the breaking of the Van der Waals bonds in the chalcogenides. Using this model, derived a relationship between the glass transition temperature, T_g and the molar volume V_m. The validity of this relation is checked using experimental data available in the literature for two binary systems (Ge-Se and As-S) and a pseudo-binary system (As₄₀Se_xTe_60-x).

3 illus, 10 ref

003161   Tanwar A;Gupta K K;Singh P J;Vijay Y K (Department of Physics, M.S.J. College, Bharatpur-321 001, Email: tanwar17msj@yahoo.com) : Dielectric parameters and a.c conductivity of pure and doped poly (methyl methacrylate) films at microwave frequencies. Bull Mater Sci 2006, 29(4), 397-401.

Dielectric properties of pure and doped poly (methyl methacrylate) (PMMA) films at microwave frequency, 8.92 GHz, have been studied at 35°C. Iodine, benzoic acid and FeCl₃ have been used as dopants. The losses in doped films are found to be larger than in pure PMMA films. The increased losses account for increased a.c. conductivity in doped films. The increase in conductivity is accounted due to creation of additional hopping sites for the charge carriers in doped samples. The dielectric data has also been used to evaluate optical constants, absorption index (A) and refractive index (K) of the films.

3 illus, 2 tables, 17 ref

003160   Srinivasa Rao N;Purnima M;Bale S;Siva Kumar K;Rahman S (Department of Physics, Osmania University, Hyderabad-500 007, Email: syedrahman848@yahoo.co.in) : Spectroscopic investigations of Cu<. Bull Mater Sci 2006, 29(4), 365-70.

Pure and copper doped glasses with composition, xLi₂O-(40-x)Na₂O-50B₂O₃-10Bi₂O₃, have been prepared over the range 0 ≤ x ≤ 40. The electron paramagnetic resonance (EPR) spectra of Cu²⁺ ions of these glasses have been recorded in the X-band at room temperature. Spin Hamiltonian parameters have been calculated. The molecular bonding coefficients, α² and β², have been calculated by recording the optical absorption spectra in the wavelength range 200-1200 nm. It has been observed that the site symmetry around Cu²⁺ ions is tetragonally distorted octahedral. The density and glass transition temperature variation with alkali content shows non-linear behaviour. The IR studies show that the glassy system contains BO₃ and BO₄ units in the disordered manner.

4 illus, 2 tables, 30 ref

003159   Sreehari Sastry S;Vijaya Lakshmi K; Ramakrishnancharya M;Rao N;Sahaya Baskaran G;Ramachandra Prabhu C, (Department of Physics, Acharya Nagarjuna University, Nagarjunanagar-522 510, Andhra Pradesh, Email: Sreehari_ssastry@yahoo.com) : Synthesis, characterization and dilatometric studies on N-(p-n-tri and tetra decyloxybenzylidene)-p-toluidine. Indian J Phys 2006, 80(2), 173-6.

Synthesis, characterization and phase transition studies are carried out on two Schiff base liquid crystal materials viz., N-(p-n-tridecyloxybenzylidene)-p-toluidine, 13O.1 and N-(p-n-tetradecyloxybenzylidene)-p-toluidine, 14O.1. The characterization studies (phases and phase transition temperatures) are carried out using polarising microscope equipped with hot stage and differential scanning calorimeter. The phase transition studies are carried out using dilatometric technique. The results infer that these two compounds possess only one monotropic liquid crystalline phase viz., smectic-A. The order of phase transition across isotropic to smectic-A is found to be of first order. The results are discussed in the light of the data available on other nO m liquid crystal compounds.

5 illus, 2 tables, 121 ref

003158   Singh V K (Department of Applied Physics, Indian School of Mines, Dhanbad-826 004, Jharkhand) : Bonding parameter and Ni K-edge position studies of some Ni systems. Indian J pure appl Phys 2006, 44(1), 20-4.

Extended X-ray absorption fine structure (EXAFS) phase shift studies of some nickel compounds have been carried out and the values of bonding parameter α₁ and phase parameter β₁ are evaluated by graphical method, α₁ is then correlated with nearest neighbour distance and ionicity of the corresponding systems. It has been observed that the bonding parameter α₁ decreases as bond distance decreases except in Ni₃(PO₄)₂.XH₂O and NiCl₂.6H2O and decreases with increase of the ionicity except for NiBr₂. The phase parameter β₁ has been correlated with oxygen atoms present in a system. The nickel K-edge position in the systems under study has been correlated with ionicity. No good relation has been observed between ionicity and edge position. This has been attributed to different structure and coordination number of a system.

4 illus, 3 tables, 18 ref

003157   Singh R A;Thakur S N (Department of Physics, Dr H S Gour University, Sagar-470 003) : High resolution electronic absorption spectrum of 2-fluoronaphthalene. Indian J pure appl Phys 2006, 44(1), 5-8.

The vapour phase absorption spectrum 2-fluoronaphthalene has been recorded under high resolution. The vibronic bands involving ground and excited normal vibrations have been assigned on the basis of their rotational contours. Many new vibrational frequencies have been reported for the first time in the excited state of 2-fluoronaphthalene.

2 illus, 2 tables, 19 ref

003156   Shinde G N;Achole P D (Research Laboratory in Electronics, Yeshwant College, Nanded-431 601, Maharashtra, Email: shindegn@yahoo.co.in) : Multiple feedback third order active-R filter with varying tapping ratio B. Indian J Phys 2006, 80(2), 187-90.

A third order active-R filter using operational amplifiers (op-amp) and resistors, is designed with multiple feedback and feedforward input signal. It is studied for different values of tapping ratio B. Center frequency F₀, circuit merit factor Q and the positive feedback resistor R which taps R₂ are kept constant at 60 kHz, 10 and 400 Ω, respectively. The circuit exhibits low pass, band pass and high pass response at corresponding output points. The gain roll-off in low-pass response is unaffected by varying tapping ratio B. Band pass response for B = 0.5 shows better gain roll-off and is more symmetric in nature. Bandwidth of the circuit decreases as B is increased. In high pass response, overshoot increases with increase in B. The gain roll-off per octave in the transient part is about +14 dB for all values of B except 0.5, but the gain gets stabilized almost at 0 dB for fi = 0.5. Thus, it gives better performance for B = 0.5. It is easy to design, suitable for monolithic IC implementation and useful for high frequency operation. It also gives better pass band gain.

4 illus, 9 ref

003155   Sarkar B C;Mandal M K (Department of physics, Burdwan University, Burdwan-713 104) : Novel technique of pulse width modulator design using a ring oscillator. Indian J pure appl Phys 2006, 44(6), 473-7.

A novel technique of pulse width modulation using a multiphase ring oscillator and a multiplexer-based digitally controlled phase shifter (DCPS) has been presented. The proposed circuit can produce 0 to 100% variation of the width of the pulse train, depending on the control word applied to DCPS. Experimental results obtained in a prototype circuit confirm the design algorithm proposed in this work.

5 illus, 5 ref

003154   Sangawar V S;Chikhalikar P S;Dhokne R J;Ubale A U;Meshram S D (Department of Physics, Government Vidarbha Institute of Science & Humanities, Amravati-444 604, Email: pal102003@yahoo.co.in) : Thermally stimulated discharge conductivity in polymer composite thin films. Bull Mater Sci 2006, 29(4), 413-16.

Describes the results of thermally stimulated discharge conductivity study of activated charcoal-polyvinyl chroride (PVC) thin film thermoelectrets. TSDC has been carried out in the temperature range 308-400°K and at four different polarizing fields. Results are discussed on the basis of mobility of activated charcoal and polyvinyl chloride chains.

3 illus, 3 tables, 10 ref

003153   Sahoo S (Department of Physics, National Institute of Technology (Deemed University), Durgapur-713 209, Email: sukadevsahoo@yahoo.com) : The prediction of mass of Z'-boson in an so(10)-based model. Indian J Phys 2006, 80(2), 191-4.

Z'-bosons are known to naturally exist in well-motivated extensions of the Standard Model. The mass of Z'-boson is considered in an S0( 10)-based model. We have used the low energy parameters and the estimated value so obtained is accessible to experiments at low energies.

38 ref

003152   Roy A K (Department of Physics, Purvottar Railway College, Sonpur-841 101) : Realisation of maximally flat transfer functions. Appl Sci Period 2005, 7(3), 165-8.

Approximation of ideal low-pass fitter characteristic is a well known topic of interests in the real of fitter theory. This is usually received by choosing polynomials of special types and then developing an all-pole transfer functions with their help. Betterworth polynomial is thus used to obtain transfer functions whose magnitude characteristic is maximally flat at the origin. A method based on evalutation of transfer function coefficients has been described to accomplish this task.

2 ref

003151   Rami Reddy M;Srinivasa Reddy M;Veeraiah N (Department of Physics, Acharya Nagarjuna University PG Centre, Nuzvid-521 201, Andhra Pradesh) : Physical properties of PbO-Al₂O₃-B₂O₃ glasses doped with Cr₂O₃. Indian J pure appl Phys 2006, 44(6), 446-54.

PbO-Al₂O₃-B₂O₃ glasses containing different concentrations of Cr₂O₃ ranging from 0 to 0.4 mol % were prepared. The dielectric properties (constant ε, loss tanδ, ac conductivity σ_ac over a range of frequency and temperature and breakdown strength) of these glasses have been studied. The results of these studies were analyzed with the aid of data on optical absorption, IR spectra and thermoluminescence studies on these glasses. The analysis suggests that the chromium ions exist in Cr³⁺ state which act as modifiers. When Cr₂O₃ is present in higher concentrations in the glass matrix, these ions seem to exist in Cr⁶⁺ state and take part in network forming positions with CrO^2-₄ structural units.

8 illus, 4 tables, 44 ref

003150   Ramesh K;Arumugam V (Department of Physics, Annamalai University, Annamalai Nagar-608 002) : Estimation of porosity and conductivity in some selected rock specimens. Appl Sci Period 2005, 7(3), 162-4.

Selected rock specimens from various locations have been collected and their porosity and conductivity is estimated by the method of water absorption and four probe resistivity method. A linear relationship is found between porosity and conductivity. This is used as a scale factor of estimating the quality of rock specimens. Some cases have been tested and results are also given.

1 table, 5 ref

003149   Rajput S;Chaudhary S;Kashyap S C (Department of Physics, Indian Institute of Technology Delhi, New Delhi-110 016) : Synthesis of MgB₂ from magnesium rich powders. Indian J pure appl Phys 2006, 44(6), 461-7.

Superconducting bulk MgB₂ samples have been synthesized by employing a modified heat treatment without using any additional process steps generally undertaken in view of the substantial loss of Mg during sintering owing to its high vapour pressure at the processing temperature. Starting with Mg rich powder mixtures having different atomic ratios of Mg:B (as against the nominally required 1:2 ratio), we have obtained superconducting MgB₂ samples showing a transition temperature (T_c) in the range 40.4-40.7 K when synthesized at sintering temperatures in the range 720-900°C. Typically, a MgB₂ sample (T_c = 40.5K) obtained from heat treating Mg and B in the ratio of 2:2 at 870°C for 1h duration exhibited critical current density in excess of 1x10⁷ A/m² at ≈38K. Our results further show that MgO is not detrimental to superconductivity.

6 illus, 1 table, 27 ref

003148   Rajesh Kumar;Rajendra Prasad (Department of Applied Physics, ZH College of Engineering & Technology, Aligarh Muslim University, Aligarh-202 002, Email: drrajesh04@rediffmail.com) : Study of ion induced modification in makrofol-KG polycarbonate by positron annihilation lifetime measurements. Indian J pure appl Phys 2006, 44(1), 9-12.

Latent ion tracks produced in the polymers due to the damage produced by the passage of swift heavy ions contain amorphous material with highest degree of disorder, changing the free volume properties, which have strong correlation with the macroscopic properties of the material. Positron Annihilation Lifetime Spectroscopy (PALS) is a non-destructive and non-interfering probe, having high detection efficiency for free volume hole properties and provides direct information about the dimension, content and hole size distribution of free volume in polymers. The effect of irradiation of Si⁸⁺ 100 MeV ions on Makrofol-KG polycarbonate by PALS is reported here. From the ortho positronium (o-Ps) lifetime, mean free volume, radius and average free volume have been obtained.

1 illus, 2 tables, 26 ref

003147   Raghavender M;Kumar G S;Prasad G (Department of Physics Materials Research Laboratory, Osmania University, Hyderabad) : Electrical properties of La-modified strontium bismuth titanate. Indian J pure appl Phys 2006, 44(1), 46-51.

Bismuth ion in four layered strontium bismuth titanate (SBT), a compound of Aurivillius family, is partially replaced with La³⁺ in the place of Bi³⁺ to synthesize SrBi_(4-x)La_xTi₄O₁₅, with x = 0.25, 0.50, 0.75. The ceramic powders were prepared using chemical route. The temperature dependence of the dielectric and impedance properties was studied over a wide frequency range. The dielectric properties showed interesting changes in the transition temperatures. These changes are correlated with the distortion that sets in the samples due to the incorporation of lanthanum. The octahedra and square pyramidal lattice distortion of the perovskite layers in ABO₃ is calculated from lattice parameters. Dielectric transition temperatures are correlated with displacement of A-site ions with respect to octahedral center.

3 illus, 1 table, 18 ref

003146   Punam Kumari;Jha D N;Mishra P K (Department of Physics, TNB College, Bhagalpur) : Study of resistivity of amorphous binary alloy using mode-coupling method. Indian J pure appl Phys 2006, 44(1), 39-45.

The mode-coupling approximation in electron-phonon interaction, which has opened a new approach for the description of electrical transport in high resistor conductors, liquid transition metals and strongly disordered systems has been extended to solid amorphous binary alloys. A simplified expression for electrical conductivity of amorphous alloys has been obtained in terms of current relaxation kernel and density relaxation kernel by adding electron-phonon coupling term in the Hamiltonian. The structure factor is allowed to vary with temperature and the product of the coupling coefficient with the static structure factor has been replaced by the T-matrix in Born approximation as in extended Ziman-Evans model. A modified formula purporting variation of packing fraction with temperature and concentration has been used to derive the TCR. The same form of packing fraction has been used for structure factors as well. Also the thermoelectric power has been calculated to verify Mooij law and study its variation with temperature. The case study of Ni_xP_1-x alloy with x=0.85 and 0.75 has been undertaken and results tested for valence values z =1.03, 1.10, 1.21 at x=.85 and z =1.28, 1.33 at x=.75 with atomic volumes 75.5, 76.60 au. It has been found that the model satisfies the experimental results both qualitatively and quantitatively.

3 illus, 17 ref

003145   Ponnusamy V;Ramasamy V;Anandalakshmi K (Department of Physics, Annamalai University, Annamalainagar-608 002, Tamil Nadu, Email: srsaranram@rediffmail.com) : Effect of preheating in biogenic shells - thermostimulated luminescence and FTIR study. Indian J pure appl Phys 2006, 44(1), 13-19.

The thermostimulated luminescence (TSL) and Fourier transform infrared (FTIR) measurements were carried out for ten biogenic shells at room temperature (RT) and various temperatures in the range 200-800°C, at an interval of 50°C. for 1 hr duration. The glow curves of unannealed sample show only one peak at 330°C. The sample irradiated with a gamma dose of 500 Gy shows an additional peak at 130°C, when recorded with linear heating rate of 10°C/s. The annealed sample also shows the same trend. Annealing treatment above 250°C increases the sensitivity of 130°C TSL peak. A sudden reduction in TSL sensitivity at 500°C is observed. At this temperature (500°C), FTIR study shows structural disorderedness or phase transition and formation of new structure in the major mineral content. On the other hand, preheating at 700°C caused a collapse in the TSL sensitivity.

4 illus, 1 table, 22 ref

003144   Pathania Y;Ahluwalia P K (Department of Physics, Himachal Pradesh University, Shimla-171 005) : Freezing transition of two-and three dimensional classical fluids using double Yukawa potential. Indian J pure appl Phys 2006, 44(1), 25-30.

Employing the techniques of molecular dynamics computer simulation, the onset of the freezing region of two and three-dimensional classical fluids interacting via Double Yukawa potential have been investigated. The radial distribution function g(r) for unique, qualitative and quantitative structural characteristics associated with the onset of freezing and for the validity of a universal freezing criterion has been studied. Authors has been compared the results with those of Lennard Jones, when parameters occurring in Double Yukawa potential are chosen to fit the Lennard Jones potential. Later, the attractive and repulsive parameters of Double Yukawa potential have been varied to study the effect of attractive and repulsive part of the potential separately on the freezing criterion.

11 illus, 2 tables, 13 ref

003143   Pant H C;Patra M K;Negi S C;Bhatia A;Vadera S R;Kumar N (Defence Laboratory, , Jodhpur-342 011, Email: nkjainjd@yahoo.com) : Conductivity and dielectric property of polyaniline zinc sulphide composites. Bull Mater Sci 2006, 29(4), 379-84.

Reported electrical conductivity and dielectric studies on the composites of conducting polyaniline (PANI) with crystanlline semiconducting ZnS powder, wherein PANI has been taken as inclusion and ZnS crystallites as the host matrix. From the studies, it has been observed that the value of room temperature d.c. conductivity of the composites with volume fraction of PANI <62> 0.65 shows an unusual behaviour wherein, conductivity values of the composites exceed that of PANI itself with maximum value as high as 6 times that of PANI at the volume fraction of 0.85. A similar trend has also been observed for the real and imaginary parts of complex dielectric constant values of the composites. This unusual behaviour in the d.c. conductivity and dielectric properties has been attributed to the enhancement in the degree of crystallinity of PANI as a consequence of its interfacial interaction with ZnS matrix. The results of optical microscopy show coating of PANI all around the ZnS particles. The temperature dependent conductivity studies suggest the quasi one-dimensional VRH conduction in PANI as well as its composites with ZnS. FTIR and XRD studies have also been reported.

7 illus, 1 table, 27 ref

003142   Pandey P K;Bhave N S;Kharat R B (Department of Chemistry, Nagpur University, Nagpur-440 033) : Structural, optical, electrical and photovoltaic elecrochemical sutdies of cobalt molybdate thin films. Indian J pure appl Phys 2006, 44(1), 52-8.

The deposition of cobalt molybdate (CoMoO₄) thin film by spray pyrolysis (SP) process, using its ammoniacal solution as precursor, has been presented. The growth of the film takes place by pyrolytic decomposition of the spraying precursor solution onto the preheated glass substrates. X-ray diffraction (XRD) studies confirm the microcrystalline. single-phase nature of the sintered thin films. Scanning electron microscope (SEM) images clearly show the aggregate of crystallites of dimensions 1-5 μm. The optical absorption studies of the sintered thin films in the wavelength range 350 - 850 nm show direct as well as indirect optical transitions in the material. The direct and indirect band gap values found to be 1.75 and 1.40 Ev, respectively. The films are semiconducting in nature and highly resistive at room temperature as evident from their dc electrical conductivity measurements obtained by the two point probe method in the temperature range 300 - 500 K. Plot of log(σ) versus 1/T clearly indicates a break in the curve corresponding to the temperature 345 K. The thin films of CoMoO₄ deposited on FTO coated conducting glass substrate were sintered in hydrogen atmosphere to be used as photoanode in photovoltaic electrochemical (PVEC) cell. The PVEC cell configuration is: CoMoO₄ | Ce⁴⁺, Ce³⁺| Pt: 0.1 M in 0.1 N H₂SO₄. The PVEC characterization reveals the fill factor and power conversion efficiency to be 0.431 and 1.20%. respectively. The flat band potential has been found to be - 0.32 V versus Standard calomel electrode (SCE).

8 illus, 35 tables,

003141   Pal D;Tandon R P;Shripal (Department of Physics, P P N P G College, Kanpur-208 001) : Correlation between EPR, dielectric spectroscopic and conductivity studies of lithium substituted Na₂Ti₃O₇ ceramic. Indian J pure appl Phys 2006, 44(6), 435-9.

The lithium substituted Na₂Ti₃O₇ ceramics with a general formula (Na_2-xLi_xTi₃O₇) with (x = 0.1) have been synthesized by high temperature solid-state reaction technique. Preliminary EPR analysis and detailed temperature and variable frequency dielectric, conductivity measurements were carried out on the prepared sample. The lithium ions are accommodated with the sodium ions in the interlayer spaee. The EPR spectrum of Na_1.9Li_0.1Ti₃O₇ confirms the partial reduction of Ti⁴⁺ ions to Ti³⁺. The observed dispersion in the dielectric constant-temperature relation can be explained on the basis of Max well-Wagner model. The conductivity plots between In (σT) versus 1000/T have been divided into four regions. The various conduction mechanisms in the different regions have been stressed in this paper. The interlayer ionic conduction seems to play major role in conduction towards higher temperature.

5 illus, 36 ref

003140   Nain M;Chauhan R P;Chakarvarti S K (Department of Physics, Government College, Karnal-132 001) : Alpha radioactive air pollutants in different types of dwellings using solid-state nuclear track detectors. Indian J pure appl Phys 2006, 44(6), 423-5.

The alpha radioactive air pollutants like radon and its progeny are the major contributors in the radiation dose received by general population of the world. It has been estimated that the radon and its progeny constitute more than 50% of the dose equivalent received by general population from all sources of radiation, both naturally occurring and man-made. Radon(²²²Rn), a progeny of ²³⁸U, is a colourless, odourless noble gas, which is radioactive, and causes health hazards not only to uranium miners but also people living in normal houses and buildings. In the present work, measurements of alpha radioactive radon and its progeny concentration in different types of dwellings of some villages in Haryana have been carried out. In cemented dwellings, the equilibrium equivalent concentration (EEC) of radon varied from 64-80 Bq m^-3 with an average of 72 ± 3 Bq m^-3 and the annual effective dose varied from 2.7-3.4 mSv with an average of 3.1 ± 0.13 mSv. In brick dwellings, the equilibrium equivalent concentration (EEC) of radon varied from 81-106 Bq m^-3 with an average of 93 ± 4 Bq m^-3 and the annual effective dose varied from 3.5 to 4.6 mSv with an average of 4.0 ± 0.02 mSv. In mud dwellings, the equilibrium equivalent concentration (EEC) of randon varied from 102-148 Bq m^-3 with an average of 125 ± 9 Bq m^-3 and the annual effective dose varied from 4.4 to 6.4 mSv with an average of 5.4 ± 0.4 mSv.

1 illus, 3 tables, 12 ref

003139   Meenakshi S;Vijayakumar V;Godwal B K (Division of High Pressure Physics, Bhabha Atomic Research Centre, Mumbai-400 085) : Melting point variation with pressure and material synthesis by a laser heated diamond anvil cell. Indian J pure appl Phys 2006, 44(6), 440-5.

The details of a high temperature-high pressure (HT-HP) facility based on the coupling of the laser heating by diamond anvil cell are described. The measured melting curve of platinum up to 12 GPa pressures is compared with existing piston-cylinder data and with theoretical calculations. The reasonable agreement reveals the utility of this technique for the reliable measurements of high temperature-high pressure phase diagrams and melting curves for materials. The suitability of hexamethylenetetramine (HMT) as a precursor for the synthesis of C₃N₄ at HT-HP, has been investigated. It is conjectured that CN_x (C₃N₄) or C:H is formed at HT-HP, but is not quenchable.

4 illus, 1 table, 27 ref

003138   Mahboob S;Prasad G;Kumar G S (Department of Physics, Osmania University, Hyderabad-500 007, Email: gskumar1948@sify.com) : Impedance and a.c. conductivity studies on Ba(Nd_0.2Ti_0.6Nb_0.2)O₃ ceramic prepared through conventional and microwave sintering route. Bull Mater Sci 2006, 29(4), 347-55.

Electrical conduction studies on Ba(Nd_0.2Ti_0.6Nb_0.2)O₃ ceramic samples prepared through conventional and microwave sintering route has been presented. D.C. and a.c. conductivities of these samples as a function of temperature from 300-900 K have been studied. Two types of conduction processes are evident from the frequency dependant conductivity plots, i.e. low-frequency conduction due to short-range hopping and high-frequency conduction due to the localized relaxation (reorientational) hopping mechanism. Grain and grain boundary contributions to the conductivity in these samples are obtained from impedance/admittance measurements via equivalent circuit modelling.

12 illus, 1 table, 19 ref

003137   Mahajan S K;Ravat K B;Kothari P C (National Physical Laboratory, , Dr K S Krishnan Marg, New Delhi-110 012) : Traceability of 100 kV dc high voltage measurements at NPL, India. Indian J pure appl Phys 2006, 44(6), 478-81.

Recently, dc high voltage laboratory has been established at National Physical Laboratory, India (NPLI) for calibration of high voltage (HV) equipment. High Voltage resistive divider is the heart of dc high voltage measurements. The traceability of HV measurements is directly related to divider's traceability to Josphson voltage standard, which is the primary standard of dc voltage. In-house calibration of HV divider using traceable dc calibrator and 10 V reference standard has been discussed in the present paper. The overall uncertainty of measurement has also been calculated and is about 10 ppm.

5 illus, 3 tables, 4 ref

003136   Madhusudhana Rao D N;Indira Devi M;Arunamani T;Ibrahim Khan, (Department of Physics, Andhra University, Visakhapatnam-530 003) : Earth-ionosphere wave guide model for rugby - Visakhapatnam path consistent with VLF phase variation measurement. Indian J Phys 2006, 80(2), 201-4.

The phase variation measurements of 16 kHz VLF transmissions from Rugby (England) made at Visakhapatnam (India) for over one year have been used as the basis to find the model for the Earth - ionosphere wave guide for the transmission path that reconciles with experimental measurements. The computations have been carried out assuming a perfectly conducting Earth and three different lower ionospheric conductivity models, namely, sharply bounded with infinite conductivity, sharply bounded with finite conductivity and a diffuse boundary with exponentially varying conductivity. It is found that the exponential model gives a diurnal phase shift or day to night shift in the height of reflection much less than what is obtained from measurements. But a sharply bounded ionosphere with finite conductivity is found to reproduce not only the diurnal height change but also the seasonal variation in it, seen in experimental data.

1 illus, 2 tables, 12 ref

003135   Kumar K;Pal K;Gupta G K (Department of Physics, DBS College, Dehradun, Uttranchal) : Realization of multi-function biquad filter using operational transconductance amplifier. Indian J pure appl Phys 2006, 44(1), 71-4.

A configuration of voltage mode (VM) multi-function biquad filters (MBF) is presented in this paper. The configuration (MBF) is implemented by using two OTAs (one dual output and other single output) and two capacitors. It realises all standard filtering functions i.e. low pass (LP), high pass (HP), band pass (BP), notch and all pass (AP). This configuration (MBF) can also be constructed using a single OTA, two capacitors and one resistor. It employs minimum of active and passive components and provides an attractive feature in case of BP filter that it can be designed for high Q. In addition, the circuit enjoy low sensitivity performance. The experimental results that confirm the validity of the circuit are included.

5 illus, 28 ref

003134   Jivani A R;Trivedi H J;Gajjar P N;Jani A R (Department of Physics, Sardar Patel University, Vallabh Vidyanagar-388120) : Electronic properties of CdS, CdSe and CdTe semiconductor binary alloys. Indian J pure appl Phys 2006, 44(1), 59-61.

The higher-order perturbation theory based on pseudopotential is used to calculate total energy, band gap at Jones-zone face and bulk modulus of CdS, CdSe and CdTe binary semiconductor compounds. The covalent correction term, which is approximately equal to third and fourth-order perturbation energy, is used in the present study. The ratio of covalent bond correction energy to second-order perturbation energy is about 15% and hence it is essential to study the electronic properties of semiconductor materials. Present theoretical results are found better than other available theoretical findings and good agreements of present finding of total energy, hand gap at Jones-zone face and bulk modulus with the experimental data are achieved.

3 tables, 22 ref

003133   Jivani A R;Trivedi H J;Gajjar P N;Jani A R (Department of Physics, Sardar Patel University, Vallabh Vidyanagar-388 120, Gujarat) : Ground state properties of ZnX (X = S, Se and Te) semiconductors. Indian J Phys 2006, 80(2), 177-80.

Electronic properties viz. total energy, band gap at Jones-zone face and bulk modulus of ZnS, ZnSe and ZnTe semiconductor compounds with zincblende structure are investigated using higher-order perturbation theory, which includes covalent correction term. For describing the electron-ion interaction in these semiconductor compounds, our proposed model potential consisting of linear and quadratic type of interaction within the core and Coulombic interaction outside the core is employed. The computed ratio of the covalent bonding term E_{cov to the second order term E?2 comes out to be 6.90% to 13.1% and hence confirms the essentiality of higher-order correction for zincblende-type cryslals. We have achieved a good agreement of present findings of total energy, band gap at Jones zone face and bulk modulus with the experimental data and other such available theoretical findings.}

4 tables, 22 ref

003132   Jeevan Kumar R;Gupta N V S;Suresh Babu C (Department of Physics, Molecular Biophysical Laboratories, Sri Krishnadevaraya University, Anantapur-515 003) : Molecular polarizabilities and related properties of few coenzymes. Biosci Res Bull 2005, 21(2), 87-90.

The parallel (Σ α<157><157>_p), non-bonded (Σα_n) and perpendicular components (Σ 2 <94>) of Polarizabilities and Mean Molecular Polarizability (α) of a few coenzymes (FMN, FAD, S-Adenosine metheonine and α_M-Lipoic acid) are evaluated quantum mechanically. The Diamagnetic Susceptibilities and Molecular Electron Ionization Cross-Sections are also evaluated from the Mean Molecular Polarizabilities. The variation in Electron Ionization Cross-Section has been discussed and the need to probe further in this direction is stressed.

2 tables, 12 ref

003131   Jayarama A;Dharmaprakash S M (Department of Physics, Mangalore University, Mangalagangotri-574 199) : Crystal growth and characterization of thiourea mixed ammonium dihydrogen phosphate. Indian J pure appl Phys 2006, 44(6), 455-60.

Single crystals of thiourea mixed ammonium dihydrogen phosphate (TADP) have been grown in solution by slow evaporation technique at ambient temperature (30°C). TADP crystallises in body centered tetragonal system with unit cell parameters a= 7.4652 Angstrom, b=7.4970 Angstrom, C=7.5415 Angstrom. The powder X-ray diffraction pattern has been recorded and indexed. The UV-Vis-NIR transmittance and FT-IR spectrum have been recorded in the range 200-1500 nm and 400-4000 cm^-1, respectively. The lower cut-off wavelength is 230 nm in the UV region, which is higher than that of ADP crystal. The presence of functional groups has been confirmed by FTIR analysis. The microhardness of TADP was evaluated using Vicker's indentation method. TADP crystals are thermally stable up to 200°C and shows optical non-linearity for Nd:YAG laser at 1.064 μm wavelength. The preliminary data indicate that the harmonic generation efficiency of TADP is three times that of pure ADP.

10 illus, 3 tables, 17 ref

003130   Jain G H;Patil L A (P.G. Department of Physics, Pratap College, Amalner-425 401, Email: lapresearch@rediffmail.com) : Gas sensing properties of Cu and Cr activated BST thick films. Bull Mater Sci 2006, 29(4), 403-11.

H₂S gas sensing properties of BST ((Ba_0.67Sr_0.33)TiO₃) thick films are reported for the first time. BST ceramic powder was prepared by mechanochemical process. Thick films of BST were prepared by screen-printing technique. The sensing performance of the films was tested for various gases. The films were surface customized by dipping them into aqueous solutions of CuCl₂ and CrO₃ for various intervals of time. These surface modified BST films showed improved sensitivity to H₂S gas (100 ppm) than pure BST film. Chromium oxide was observed to be a better activator than copper oxide in H₂S gas sensing. The effect of microstructure and amount of activators on H₂S gas sensing were discussed. The sensitivity, selectivity, stability, response and recovery time of the sensor were measured and presented.

11 illus, 2 tables, 36 ref

003129   Gupta K;Raina K K;Sinha S K (National Research and Technology Consortium, , Sector-1, Parwanoo-173 220, Email: rainatietp@yahoo.com) : Influence of nickel addition on magnetic and electro-mechanical behaviour of permalloys. Bull Mater Sci 2006, 29(4), 391-6.

Magnetic and electro-mechanical investigations have been carried out in two Ni-Fe permalloys under hydrogen atmosphere by varying annealing temperature. These alloys have been characterized for various magnetic parameters like peak permeability, coercivity and core loss under changed annealing profile conditions. The magnetic properties of Ni-rich (Ni <126> 82%) alloy at 100 Hz were found to be better than the low Ni (Ni <126> 47%) alloy. The alloys were tested for watch movement and found that the battery life of the watch movement improved by 38% using Ni-rich permalloy.

4 illus, 5 tables, 15 ref

003128   Gohain Barua A;Tiru B (Department of Physics, Gauhati University, Guwahati-781 014) : Variation of width of the hysteresis loop with temperature in an emitter-coupled schmitt trigger. Indian J pure appl Phys 2006, 44(6), 482-5.

Schmitt trigger circuits are designed with pnp transistors: the first circuit with two 2SB324 germanium transistors, and the second one with two U188 silicon transistors. At certain collector resistances in the second stage- or the driven-transistor, the variations of the hysteresis loop width in temperature range -95-75°C for the first circuit, and 100-150°C for the second one have been observed. The increase in the loop width with temperature is shown.

4 illus, 2 tables, 12 ref

003127   Ghosh J;Chattopadhyay S K;Meikap A K; Chatterjee S K (Department of Analytical Facility & XRD, Central Glass and Ceramic Research Institute, Kolkata-700 032, Email: jiten@cgcri.res.in) : Microstructural studies on variation of defect parameters in Zr-Sn alloys and their transition with interchange of solvent and solute in Zr-Ti and Ti-Zr alloy systems by modified Rietveld method and Warren-Averbach method. Bull Mater Sci 2006, 29(4), 385-90.

The effects of deformation and the transition of microstructural defect states with the interchange of solvent and solute in Ti-Zr and Zr-Ti alloys of six different compositions and Zr-Sn alloys in three different compositions have been investigated by X-ray diffraction line profile analysis. The detailed analysis of the X-ray powder diffraction line profiles was interpreted by Fourier line shape analysis using modified Rietveld method and Warren-Averbach method taking silicon as standard. Finally the microstructural parameters such as coherent domain size, microstrains within domains, faulting probability and dislocation density were evaluated from the analysis of X-ray powder diffraction data of Zr base Sn, Ti and Ti base Zr alloys by modified Rietveld powder structure refinement. This analysis confirms that the growth fault, β, is totally absent or negligibly present in Zr-Ti, Ti-Zr and Zr-Sn alloy systems, because the growth fault, β, has been observed to be either negative or very small for these alloy systems. This analysis also revealed that the deformation fault, α, has significant presence in titanium-base zirconium alloy systems but when zirconium content in the matrix goes on increasing beyond 50%, this faulting behaviour suffers a drastic transition and faulting tendency abruptly drops to a level of negligible presence or zero. This tendency has also been observed in Zr-Sn alloys signifying high stacking fault energy. Therefore, Zr and Zr-base alloys having high stacking fault energy can be used as hard alloys in nuclear technology at high temperature.

2 illus, 4 tables, 22 ref

003126   Gautam A K;Vishvakarma B R (Department of Electronics Engineering, Institute of Technology, Banaras Hindu University, Varanasi-221 005 UP) : Frequency agile microstrip antenna using symmetrically loaded tunnel diodes. Indian J Radio Space Phys 2006, 35(3), 212-16.

A frequency agile microstrip antenna using symmetrically loaded tunnel diodes is proposed, in which the operating frequency of the rectangular microstrip antenna is electronically controlled by the bias voltage of the tunnel diode. Theoretical investigations, based on a modal cavity modol are carried out for the GaAs tunnel diode. The tuning range was found to be 55.92 MHz (6.67%), which is much better than earlier reported result.

9 illus, 12 ref

003125   Gartia R K;Ranita U;Basanta Singh T, (Luminescence Dating Laboratory, Manipur University, Imphal-795 003) : Mathematical modeling of glow peaks of fluorites relevant to dosimetry and dating. Indian J Phys 2006, 80(2), 181-5.

Mathematical modeling of glow peaks (as many as eleven in the range of 30-600°C) of fluorites (light green) of Indian origin relevant to dosimetry and dating, has been successfully achieved to a high degree of certainty in the frame work of general order kinetics formalism. The criteria to accept the goodness of fit between the experimental glow curve and the numerically generated best fit curve, is judged not from the figure of merit (FOM) as conventionally done but from a rather rigorous criteria i.e. the Chi-square (X²) test. With this achievement, it has been possible to estimate the lower limit lifetime ( τ ) of electrons trapped at deep levels of fluorile. The values of τ is found to lie in the range of 10¹⁶ - 10²³ years at 300°K. Thus, the high temperature glow peaks have potential use in determining the time of mineralisation of the material. In fluorite, these glow peaks occur at 398°C, 439°C, 477°C and 545°C for a moderate heating rate (β) of 0 25°Cs^-1.

7 illus, 2 tables, 30 ref

003124   Garg M;Sharma A;Quamara J K (Department of Applied Physics, National Institute of Technology, Kurukshetra-136 119) : Surface chemical etching behaviour of pristine and high energy Li ion irradiated kapton-H polyimide. Indian J pure appl Phys 2006, 44(1), 66-70.

High energy heavy ion irradiation effect on surface chemical etching behaviour of kapton-H polyimide has been studied using NaOH (40°C) and NaOCl (55°C) as etchants. The samples have been irradiated with 50 MeV Li ions (fluence 10⁵ ions/cm² at Pelletron Facility, Nuclear Science Center, New Delhi). The etching behaviour is non-linear in NaOH for both pristine and irradiated samples. There is an enhancement in the etching rate in irradiated samples for both NaOH and NaOCl etchants. The etching mechanism of pristine and irradiated kapton-H polyimide with NaOCl and NaOH has been investigated. In irradiated samples the demerization of carbonyl groups, breaking of imide linkages and increase in crystallinity have been held responsible for the change in the etching behaviour. The bulk activation energy of pristine and irradiated samples for NaOH (0.38 and 0.30 eV) and NaOCl (1.6 and 1.3 eV) has been estimated. High temperature vacuum annealed samples when etched with NaOH show swelling instead of etching, which is due to a unique type of gel formation taking place on the surface.

8 illus, 1 table, 11 ref

003123   Gaikwad P D;Shirale D J;Gade V K;Savale P A; Kakde K P;Kharat H J;Shirsat M D (Department of Physics, Dr B A Marathwada University, Aurangabad-431 004, Email: mdshirsat_bamu@yahoo.co.in) : Potentiometric study of polyaniline film synthesized with various dopants and composite-dopant: a comparative study. Bull Mater Sci 2006, 29(4), 417-20.

Potentiometric study of polyaniline (PANI) film synthesized with dopants viz. polyvinyl sulfonic acid (PVS) p-toluene sulfonic acid (pTS), dodecyl benzene sulfonic acid (DBS) and composite-dopants viz. PVS-pTS and PVS-DBS, has been carried out. The synthesized PANI films were characterized by electrochemical technique, UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and conductivity measurement. It was found that the PANI doped with PVS gives good electrochemical properties, conductivity as well as surface morphology as compared to pTS and DBS, whereas in composite dopants the PANI doped with PVS-pTS gives good polymer matrix as compared to PVS-DBS.

8 illus, 2 tables, 18 ref

003122   Eraiah B (Department of Physics, Bangalore University, Bangalore-560 056, Email: eraiah@rediffmail.com) : Optical property of samarium doped zinc-tellurite glasses. Bull Mater Sci 2006, 29(4), 375-8.

Glasses with the composition, (Sm₂O₃)_x(ZnO)_(40-x)(TeO₂)₍₆₀₎, were prepared by conventional melt quenching method. The density, molar volume, and optical energy band gap of these glasses have been measured. The refractive index, molar refraction and polarizability of oxide ion have been calculated by using Lorentz-Lorentz relations. Optical absorption spectra of these glasses were recorded in the range 300-700 nm at room temperature. The oxide ion polarizabilities deduced from two different quantities, viz. refractive index and optical energy band gap, agree well compared with other glasses. The nonlinear variation of the above optical parameters with respect to samarium dopant has been explained.

4 illus, 1 table, 21 ref