011732   Raja Sudha G;Vimala Devi K;Arthi D; Subramanian S P;Srinivasan N;Saravanan R (Physics Dep, Thiagarajar College, Madurai - 625 009) : Experiment f" of As at 170, 200, 250 and 300 K from the Bijvoet pairs of GaAs. Bull Mater Sci 2002, 25(4), 325-7.

Anomalous dispersion effects lead to the modification of the measured X-ray structure factors. The imaginary part of the anomalous dispersion correction terms (f") of arsenide atom (As) has been determined through the X-ray data collected using spherical single crystal of GaAs, at various temperatures, viz., 170, 200, 250 and 300 K. It is stressed that more measurements of f" of the elements are needed to confirm the theoretical calculations.

5 tables, 7 ref

011731   Radhakrishnan J K;Sithraman S;Gupta S C (Solid State Physics Laboratory, , Lucknow Road, Delhi-110 054) : Characteristics of HgCdTe epilayer grown by LPE using horizontal slider. Bull Mater Sci 2002, 25(6), 483-6.

The characteristics of HgCdTe epilayers grown in a modified horizontal slider system, are reported. The surface morphology of the grown layers, their IR transmission characteristics, depth and lateral compositional uniformity, structural and electrical characteristics are discussed.

5 illus, 2 ref

011730   Prasad R K;Rahmani S (Department of Physics, Women's College, Samastipur-848 101) : Thermo powers of metals when more than one contribution is involved. Acta Cienc Indica-Phys 2002, 28(4), (NULL).

In a conductor in which the electrons are scattered in more than one way (e.g. by lattice vibrations and impurity atoms). Notices even a great change in the thermopower of the conductor [Mac Donald (1962), Barnard (1972)]. Hence the thermoemf and thermopower of a thermocouple of a given pair of meatals as measured by different authors do not agree with each other. Focuses our attention to the effect on the diffusion thermopower of additional scattering processes and examine the discrepancy between theory and experiments of the thermopowers of individual conductors and their thermoscouples.

4 illus, 15 ref

011729   Prasad R K;Rahmani S (Department of Physics, Women's College, Samastipur-848 101) : Variation of thermopowers of metals with reference metals and temperatures. Acta Cienc Indica-Phys 2002, 28(4), 191-205.

Thermopowers of metals must have same value irresoective of the reference metals used, but this is not the case and there is variation of thermopowers of metals with respect to reference metals and their variation with temperature is also not the same with different reference metals.Why is it so? Analyses this fact and tries to explain in a different way.

4 illus, 5 tables, 13 ref

011728   Prakash T;Narayan Dass S A K;Prem Nazeer K (Dep of Nuclear Physics, Madras University, Chennai-600 025) : Thermal sensor properties of PANI(EB)-CSA_x (X=0.4±0.1 mol) polymer thin films. Bull Mater Sci 2002, 25(6), 521-6.

Films of polyaniline (EB) doped with camphor sulfonic acid (CSA) from m-cresol on glass substrates exhibit considerable metallic properties. Such polymer metallic films have thermal sensitivity superior to ceramic metal (Cermet) films, prepared by metallo organic deposition (MOD) technique on silicon substrates. The PANI(EB)-CSA_x (x=0.5, 0.4, 0.3 mol)) polymer films were developed through controlled temperature atmosphere 60±2C for 60 min, and with the help of temperature dependence of resistivity (p) values, high temperature coefficient of resistance (TCR) i.e. α values, and figure of merit (pα) value of these films, thermal sensitivity werecompared from that we observed. Among the three doping ratios the PANI(EB)-CSA_{0.3 mol} film (4.4μm thick) on glass substrate resistivity (p) values in the range of 838-1699 Ω μm with high TCR i.eΩ=10,291 ppm/°C and figure of merit (pα) value in range of 8.62-17.48Ωm/°C seems to be the best. This paper deals with these superior thermal-sensing properties together with optical studies and surface topography by atomic force microscopy (AFM). These polymer films offer design advantages in developing `thin film polymer thermal sensor'.

2 tables, 11 ref

011727   Patel I B;Poria K C (Department of Physics, South Gujarat University, Surat,Gujarat-395007) : Calculate activation energy for thiourea crystals grown by evaporation technique.. Appl Sci Period 2002, 4(4), 185-9.

The thermal behaviour of the crystal is studied by using Thermal Gravimetric Analysis (TGA) and Different Thermal Analysis (DTA). Thermal degradation % weight loss and qualitative estimation of thermal stability has been reported with thermograms. Activation energy were calculated with Broido Method. The type of reaction is known through the DTA graph. The results of the investigation are reported.

4 illus, 1 table, 8 ref

011726   Padte J C;Padte N J (NO, Fie Research Insitute, Ichalkaranji-416 116) : Recent trends and accuracies involved in contactless measurements using image processing techniques with special focus on material testing. MAPAN 2003, 18, 125-30.

Modern trends call for more and more accurate measurements at higher speeds preferably without physical contact with the measurand. This is achievabel by grabbing the image of the measurand, analyzing the size and shape and measuring the dimension with very advanced technique like image processing. The extension of these procedures are used to material testing like Vickers and Brinell hardness testing and analyzing the present stateof material. Extensive software is developed to ahieve the higher speeds, accuracies and repeatability in the measurement.

2 illus, 4 ref

011725   Murugan P;Pothiraj R;Roy S D D;Ramachandran K (School of Physics, Madurai Kamaraj University, Madurai - 625 021) : Si diffusion in GaAs. Bull Mater Sci 2002, 25(4), 335-40.

Theoretical studies are carried out to ascertain the dominant mechanism of Si diffusion in GaAs. Lattice dynamical model calculations have shown that the most probable diffusion mechanism is through a single vacancy even though several experiments cannnot fix the mechanism as substitutional, substitutional-interstitial pair or neutral defect pair.

3 illus, 4 tables, 23 ref

011724   Mohanta D;Nath S S;Mishra N C;Choudhury A (Physics Dep, Tezpur University, P O Napaam, Assam-784 028) : Irradiation induced grain growth and surface emission enhancement of chemically tailored ZnS : Mn/PVOH nanoparticles by Cl<. Bull Mater Sci 2003, 26(3), 289-94.

Managanese doped zinc sulfide nanoparticles are fabricated on polyvinyl alcohol dielectric matrix. They are bombarded with energetic chlorine ions (100 MeV). The size of the crystallites is found to increase with ion fluence due to melting led grain growth under ion irradiation. The increased size as a result of grain growth has been observed both in the optical absorption spectra in terms of redshift and in electron microscopic images. The photoluminescence (PL) study was carried out by band to band excitation (λex=220 nm) upon ZnS : Mn, which results into two emission peaks corresponding to surface states and Mn⁺² emission respectively. The ion fluence for irradiation experiment so chosen were 1 x 10¹¹, 5 x 10¹¹, 5 x 10¹² and 10¹³ Cl/CM².

3 illus, 3 tables, 45 ref

011723   Mohan P (NO, National Physical Laboratory, New Delhi-110 012) : Generation of pressures at NPL, New Delhi for CCM key comparison CCM. P-K3 in absolute pressure (10<. MAPAN 2003, 18, 131-7.

Presents the details of the transfer standard package privided by the pilot laboratory. It will breifly discuss themethods used at NPL to generate the six mandatory pressure points. viz., 3x10^-6 Pa, 9x10^-5Pa, 3x10^-3Pas and the seventh opional point 3x10^-3 Pa for the SRGs. The measurements at NPL were performed on the Origice Flow High Vacuum System (OFS) which is a primary standard. The limits and uncertainties of the OFS will also be presented.

2 illus, 2 tables, 6 ref

011722   Mishra S;Ghanshyam C;Nathai Ram;Satinder Singh;Bajpai R P;Bedi R K (Microelectronics Group, Central Scientific Instruments Organization, Sector-30, Chandigarh-160 020) : Alcohol sensing of tin oxide thin film prepared by sol-gel process. Bull Mater Sci 2002, 25(3), 231-4.

Describes the alcohol sensing characteristics of spin coated SnO₂ thin film deposited by using sol-gel process. The sensitivity of the film was measured at different temperatures and different concentrations of alcohol at ppm level. Alcohol detection result shows pea sensitivity at 623 K. The variation of sensitivity and ethanol concentration has shown a linear relationship up to 1150 ppm and after that it saturates. The response time measurement of the sensor was also observed and it was found that the response time is 30 sec. The results obtained favour the sol-gel process as a low cost method for the preparation of thin films with a high sensing characteristic.

4 illus, 12 ref

011721   Mathe V L;Patankar K K;Lotke S D;Joshi P B; Patil S A (Physics Dep, Shivaji University, Kolhapur - 416 004) : Structural, dielectric and transport properties of Pb(Mn_0.5W_0.5)O₃. Bull Mater Sci 2002, 25(4), 347-50.

Polycrystalline Pb(Mn_0.5)W_0.5)O₃, a ferroelectric oxide having perovskite structure, was prepared by high temperature solid state reaction technique. Preliminary X-ray diffraction analysis confirms single phase formation with the lattice parameters a = 7.2501 AÅ, b = 8.1276 AÅ and c = 12.0232Å. Room temperature dielectric constant (ε') and loss tangent (tan δ) were scanned with respect to frequency in the range 100 Hz-1 MHz. Detailed study of dielectric constant and electrical conductivity reveals a phase change around 400 K, which is quite different from those in the other materials of the same type. Further, the seebeck coefficient α) is temperature independent. The condition is interpreted as due to small polaron hopping.

6 illus, 16 ref

011720   Mahapatra R;Kar G S;Samantaray C B;Dhar A; Bhattacharya D;Ray S K (Dep of Physics of Meteorology, Material Science Centre, Indian Institute of Technology, Kharagpur-721 302) : ZrO₂ as a high - k dielectric for strained SiGe MOS decices. Bull Mater Sci 2002, 25(6), 455-7.

4 illus, 17 ref

011719   Lakshmi N;Pndey A;Venugopalan K (Physics Dep, Mohanlal Sukhadia University, Udaipur - 313 001) : Hyperfine field distributions in disordered Mn₂CoSn and Mn₂NiSn Heusler alloys. Bull Mater Sci 2002, 25(4), 309-13.

Heusler alloys, Mn₂CoSn and MN₂NiSn, were prepared and characterized by X-ray studies. Mossbauer studies using Sn-119 were carried out to investigate the hyperfine fields present at the Sn site in these alloys. The hyperfine field distribution in these alloys as well as X-ray studies point to the chemical disorder present in both alloys. Co-existence of a paramagnetic portion along with the magnetic hyperfine part was observed in Mn₂CoSn even at low temperatures, while this was not found in Mn₂NiSn spectra. Hyperfine fields at Sn site were calculated usign Blandin and Campbell model and comapred with the experimental results.

4 illus, 3 tables, 14 ref

011718   Lakshmi N;Chandra S (Physics Dep, Banaras Hindu University, Varanasi-221 005) : Ion transport in some solid state proton conducting composites studied from volta cell e.m.f. and complex impedance spectroscopy. Bull Mater Sci 2002, 25(3), 197-201.

Proton conducting composites of heteropolyacid hydrates (phosphomolybdic acid H₃PMo₁₂O_{40.nH2O, PMA; phosphotungstic acid H3PW1240nH2O, PTA) and salt hydrate like NiCl26H22O3 as dispersoid. The ionic conductivity peaks at two concentrations of Al2O3 indicating two percolating thresholds for proton conduction. Two separate experiments were carried out to check the existence of such percolation thresholds viz. the volta compositions used as electrolyte and the composition vs conductivity measured by the complex impedance spectroscopy. The presence of two maximua has been attributed to two different percolation thresholds for the two possible mobile protonic species H⁺ (H3O⁺) and OH^- arising from the hydrates.}

5 illus 19 ref

011717   Laha U (Dep of Physics, Regional Institute of Technology, Jamshedpur-831 014) : On the solution of relativistic schrodinger type equation for confining potentials. Appl Sci Period 2003, 5(1), 1-3.

Relativistic Schrodinger type equation for light quark system is studied for certain confining potentials (Linear and Coulomb) and some new results are presented.

7 ref

011716   Karmakar N C;Sastry B S;Singh R P (Dep of Mining Engineering, Indian School of Mines, Dhanbad-826 004) : Flocculation of chromite ore fines suspension using polysaccharide based graft copolymers. Bull Mater Sci 2002, 25(6), 477-8.

Graft copolymers are being experimented at the laboratory scale as flocculants. All the four graft copolymers, viz., starch-g-polyacrylamide, amylopectin-g-polyacrylamide, sodium alginate-g-polyacylamide and carboxymethyl cellulos-g-polycrylamide performed well as flocculants on chromite ore fines suspension. Amylopection-g-polyacrylamide, in particular, performed superior to the rest of the series from the point of view of settling velocity of flocs which is the most important aspect in solid-liquid separation.

2 illus, 4 ref

011715   Kalamse G M;Nimkar M J (Department of Physics, Science College, Nanded-431 605) : Finite element analysis of rectangular membrane with boundary deformation. Acta Cienc Indica-Phys 2002, 28(3), 145-50.

A thin stretched rectangular vibrating membrane has been analysed by using Finite Element Method (F.E.M.). This membrane is subjected to various boundary deformation. The resonant frequencies obtained from F.E.M. program are represented graphically. The nodal curves for fundamental frequency and first harmonic are also plotted. It is found that the deformation of the rectangular membrane splits the degenerate states. The fundamental frequency increases slowly with the position as well as size of the deformation. Again it is found that whether the membrane is deformed or not, the nodal lines are the boundary lines for fundamental frequency. However for first harmonic, the nodal line which passes from one corner to another corner of Square membrane, Changes its orientation, as per the position of deformation.

7 illus, 3 tables, 10 ref

011714   Johri G K;Srivastava C K;Johri M;Dwivedi D C; Sanjay Kumar;Gupta D C;Johri S;Sharma R (Department of Physics, D.A.V.College, Kanpur) : Experimental study of organic liquids in solutions in polar solvents using ultrasonic technique. J pure appl Ultrasonics 2002, 24(2), 54-60.

ultrasonic velocity measurement is reported to see the effect of change of functional groups -H₂₃-, (CH₃)₂-, C₂H₅-, C₄H₉-and C₅H₁₁-;) at different positions. The measurements of ultrasonic velocity have been supplemented with the observed values of density to analyze the data for the calculation of Adiabatic compressibility (β_a), Rao number (R_n) and Wada constant (β_w). This work is useful to understand the solutes in the same solvent and vice-versa.

4 illus, 2 tables, 14 ref

011713   Jayaraj M K;Antony A;Ramachandran M (Physics Dep, Cochin University of Science and Technology, Kochi-682 022) : Transparent conducting zinc oxide thin film prepared by off-axis rf magnetron sputtering. Bull Mater Sci 2002, 25(3), 227-30.

Highly conducting and transparent ZnO :Al thin films were grown by off-axis of magnetron sputtering on amorphous silica substrates without any post-deposition annealing. The electrical and optical properties of the films deposited at various subrate temperatures and target to substrate distances were investigated in detail. Optimized ZnO : Al films have conductivity of 2200 S cm^-1 and average transmission in the visible range is higher than 85%. The conductivity and mobility show very little temperature dependence.

9 illus, 16 ref

011712   Jana D (Department of Physics, University College of Science and Technology, Kolkata-700 009) : On dielectric constant of water and water vapour. Phys Educ 2002, 19(3), 247-56.

Discusses the response of polar and non-polar molecules in presence of an external electric field. Uses Clausius-Mossotti relation compute the dielectric constant for non-polar molecule. Finally, takes up the case of water as a polar molecule and estimates its dielectric constant from Onsager's theory.

2 illus, 12 ref

011711   Jain R;Bagchi S N (Vibration Engg.-Design Dept., RPL, B-103, Sector-5, Noida-201 301) : Design of vibration isolation systems for metrological laboratories in industrial environment. MAPAN 2003, 18(Jan-Mar), 211-16.

An overview of nature of forces inducing vibrations and oscillations in heavy lumped masses, machines and molecules are briefed. The associated frequency spectrum for the varied order of magnitude is just touched upon for comparision. However, we will confine to the interaction of gravitational forces with static and dynamic loading of machines and structures in the vibration isolation system application. Earlier the sophisticated instruments were used in a laboratory environment where the random vibration input Power Spectral Density (PSD) values are of low order. But now a days metrological instrument like Co-ordinate Measuring Machines (CMM), Optical Interferometer, Laser based instruments are being used in a quality control laboratory in an industrial atmosphere where the disturbances are of much higher order. It is still severe when the laboratory is situated near a press or forging shop. The design consideration of a multi stage frequency separated isolation system is highlighted along with air spring systems.The mathematical analysis in 3D and isolator selection methods are described in industrial context. In conclusion the correlation between mathematically designed isolation system and the actual industrial installations are presented along with the application of isolation system for seismic protection of sensitive instruments.

21 ref

011710   jain K M (Physics Dep, Institute of Excellence in Higher Education, Bhopal-462 017) : Understanding Matter: Quark-lepton model success and problems ahead. Phys Educ 2002, 19(3), 193-7.

The 'quark-lepton' model commonly known as "standard model" met with brilliant success in understanding the micro-world. This model does not take into account the gravitational interactions. Another approach in form of "string theory" is promising in this respect.

5 ref

011709   Gupta A;Varma S P; (NO, Dyal Singh College, University of Delhi, New Delhi-110 003) : Infrared spectroscopic studies on adehydrophenylalanine acid containing model peptide:Boc-Ala - (<177>). MAPAN 2003, 18, 63-6.

Variabel temperature IR studies on left handed helical peptide designed using four consecutive ∇Phe residuaes (Boc- Ala - ∇)⁴- NHMe have been reported here. The thin solid films of peptides were obtained on an IR transparent material and their spectra were collected in mid IR range as a function of temperature. Mathematical analysis of spectral data was performed to study the unfolding of folded conformations as a function fo temeperature and elucidate the conformational changes based on spectra - structure correlatin. The spectral studies are reported based on mainly amide I spectra region (1600-1700 cm^-1), and the hydrogen bond sensitive region (3200-3400 cm^-1.

2 illus, 5 ref

011708   George R;Patel I B (Department of Physics, South Gujarat University, Surat-395 007) : Growth studies for calcium phosphates (brushite) crystals in gel method. Acta Cienc Indica-Phys 2002, 28(3), 137-40.

Brushite plays an important role in the formation of metabolic, non-metabolic stones, bones and teeth. Brushite crystals are grown by gel method. The author have successfully grown them by gel method at ambient temperature in a normal test tube. The effects of concentration of feed solution and mother solution, pH and that of gel density on crystallisation have been studied. On average 90 of the crystals obtained were found to be transparent. The crystal size ranged about 35 mm x 8 mm x 6 mm. The results are reported.

2 illus, 2 tables, 7 ref

011707   Garg R K;Ram R S (NO, National Physical Laboratory, New Delhi-110 012) : Calibration of Broad band UV intensity meters. MAPAN 2003, 18, 67-72.

ultraviolet radiation emitted from natural and artificial sources has found applications in many fields including industrial, agricultural, scientific, medical, technological, health and safety etc. These appliations have generated accurate and low cost measurement and calibration requirement s of UV sources and measuring instruments. However, the exponential decrease of solar irradiance of five orders of magnitudes especially inthe UV-B(280-320 nm) spectral range with decreasing wavelength, coupled with relatively large amount of solar irradiance at larger wavelength (Visibel and IR radiation)put very stringet requiremnts on measuring instruments. Broadband, low cost UV-A, UV-B and UV-C intensity meters with accuracy of the order of ± 10% arebeing widely used for the measurement purposes in the laboratories and industries vary considerably. For the UV-A meter, errors ranging from 18 to 42% were observed. This is because of non-existence of accepted standard specification adn the components used in the fabrication fo the UV Intesity Meters by different manufacturer specially the filters. Calibration procedures and typical measurement results of few UV Intesity meter will be described.

2 illus, 3 tables,5 ref

011706   Durai S;Babu P (Department of Physics, A.M. Jain College, Chennai-600 114) : Influence of second order elastic constants on debye temperature and superconducting transition temperature. Acta Cienc Indica-Phys 2002, 28(3), 129-32.

A modified empirical relation connecting the Debye Temperature and second order elastic constants has been tried and applied to eight metals. All the related parameters like the superconducting transition temperature and electronic specific heat coefficients are also evaluated. The results are good supporting the theoritical approach. As a self test of this theory, a reverse calculation viz. evaluation of the elastic constants from the experimental values of Debye temperature is also attempted.

3 tables, 10 ref

011705   Dissanaike G (Department of Physics, University of Peradeniya, Peradeniya, Sri Lanka) : Sunrise from high altitude in clear and polluted skies. Phys Educ 2002, 19(3), 257-62.

Presents few photographs of sunrise taken at high altitudes on two occasions, when the skies were clear and clean over the Indian Ocean, and when the skies were over the Middle East were intensely polluted as a result of the Kuwait oil fires of 1991. The colours seen in the sky at high altitude on these two occasions are in striking construct, conveying an important message concerning atmospheric pollution. A most colourful picture of a sunrise taken from admist the hills of Kandy shows Nature as its best, and confirms that the atmosphere over the region is clean and free of pollution.

6 illus, 2 ref

011704   Dilwar N;Varandani D;bandyopadhyay A K; (NO, National Physical Laboratory, New Delhi-110 012) : Differential pressure measurments through automated data acquisition. MAPAN 2003, 18, 25-33.

Describes thecharacterizationof a differential pressure transducer against a twin pressure balance using the automated data acquisition through on A/D interface card. The transducer is a strain gauge type with a differrential pressure range of 0-3.5 MPa upt to a high line gas pressure of 7 MPa and a reported accuracy of 0.04% FS. The twin pressure balance used for characterization isthe secondary pneumatic pressure standard NPL-8,with a pressure range of 0-20 MPa and with a relative expanded uncertainty in the pressure measurement of 30 x 10^-6 (at k=l) for each balance. The data card is a 16-bit A/D card, which is used through the software developed in Visual Basic. The data is acquired in trigger-operated mode at a sampling rate of 10k. The transducer is characterized at line pressure of 0.5, 2, 3.5, 5 and 7 MPa. The details of the characterization are discussed.

6 illus, 3 tables, 10 ref

011703   Dhote D S;Yawale S P;Yawale S S (NO, , ) : Structural characterization of vanadium-borate semiconduction glasses. Acta Cienc Indica-Phys 2002, 28(4), 185-90.

Structural characterization of semiconduction V₂O₅-B₂O₃ glass system for 5-25 mol of V₂O₅ is done. The percent crystallinity is found to be negligible as compared to the amorphous state hence the over all behaviour in the properties would be due to amorphous nature. The randomly connected BO₃ and BO₄ groups may be associated with some spaces (intertials) between them and the intertials are occupied by the V⁴⁼ and V⁵⁼ ions. The values of glass transitions temperature are found to be small as compared to the other glasses, indicating the glasses are soft.

3 illus, 2 tables, 4 ref

011702   Dey T K;Ray A;Ghatak DS K (Cryogenic Engineering Centre, Dep of Physics and Meteorology, Indian Institute of Technology, Kharagpur-721 302) : A novel method for sensing rotational speed, linear displacement and current using superconducting BPSCCO magnetic sensor. Bull Mater Sci 2002, 25(6), 463-7.

The characteristics of a magnetic sensor, based on the non linear electromagnetic response of the weak links present in the polycrystalling BPSCCO super conductor are reported. the second harmonic response of sintered superconducting BPSCCO pellet in an alternating magnetic field at 40 kHz and 77 K being a strong linear function of low d.c. magnetic field has been utilized for the development of highly sensitive magnetic field sensors.The noise limited resolution of the sensor is found to be 3.16x10⁹T/√Hz for H_a.c.=16 Oe and frequency 40 kHz.

4 illus, 16 ref

011701   Dey A;Chatterjee M;Naskar M K;Dalui S;Basu K (Sol-Gel Div, Composite Div, Central Glass and Ceramic Research Institute, Kolkata-700 032) : A novel technique for fabrication of near-net-shape CMCs. Bull Mater Sci 2002, 25(6), 493-5.

A sol-gel vacuum infiltration technique has been developed for the fabrication of near-net-shape ceramic matrix composites (CMCs) using discontinuous mullite fibre perform with 15 vol. % of fibre content and ZrO₂.10wt.% Y₂O₃

3 illus, 1 table, 3 ref

011700   Das S K (Department of Physics, Maulana Azad College, Kolkata-700 013) : Thermodynamics of an ideal gas in a constant gravitational field. Phys Educ 2002, 19(3), 205-10.

Thermodynamic properties of an ideal gas in a gravitational field are studied by using the conventional laws of thermodynamics. Investigations reveal striking differences with those of an ideal gas in absence of the gravitational field.

2 illus, 1 table, 4 ref

011699   Das M L; (NO, National Physical Laboratory, New Delhi-110 012) : Corrosion study of materials used for fabricating mass standards. MAPAN 2003, 18, 115-17.

Stainless steel, Ni-Cr alloy, platinum, aluminium, brass and cast iron are generally used for fabricating various types of standards fo mass or weights. But the stability of all these weights is affected by corrosion. to findout the extent of instability of the weights, corrosion tests were caried out in Mass Metrology Section of NPL, New Delhi. Accelerated corrosion test (ASTM, D-2247) and indoor corrosion test were carried out for the samples of above mentioned materials. Outdoor corrosion test was carried out only for iron sample. Accelerated corrosion rates were found as 94.93, 161.14, 200.00, 677.08, 896.86, 44140.39 and indoor corrosion rates were found as 2.52, 4.79, 5.74, 24.26, 31.56, 65.56 for platinum , stainless teel, Ni-Cr alloy, aluminium, brass and cast iron samples respectively. Outdoor corrosion rate for cast iron sample was found as 2436367. Corrosionn rates (mass gain)were calculated in the unit of ±g/cm² hrx 10^-4.

2 tables, 3 ref

011698   Das B P;Choudhary R N P;Mahapatra P K (Dep of Phy and Meteorology, Indian Institute of Technology, Kharagpur-721 302) : Structural, dielectric and electrical properties of Sm-modified Pb(SnTi)O₃ ferroelectric system. Bull Mater Sci 2002, 25(6), 517-19.

Synthesized (Pb_1-xSm_x)(Sn_yTi_1-x/4O₃ (PSmST) polycrystalline ferroelectric ceramics with X = 0.05, 0.07 and y = 0.45 by a solid-state reaction technique and performed preliminary X-ray diffraction (XRD) analysis, detailed temperature and frequency dependence dielectric measurements on them. The a.c. conductivity has been investigated over a wide range of temperature and the activation energy (E_a.c) has also been calculated. It is observed that (i) the dielectric permittivity (ε) and loss tangent (tan δ) are dependent on frequency, (ii) the temperature of dielectric permittivity maximum shifts toward lower temperature side with the increase of samarium ion (Sm⁺³) concentration at the Pb sites, and (iii) observed and calculated d-values of XRD patterns show that the compounds have been formed in orthorhombic single phase.

6 illus, 2 table

011697   Chakravarty B C (Electronic Materials Div, National Physical Laboratory, New Delhi-110 012) : Calibration methods of solar cells and panels. MAPAN 2003, 18, 15-23.

The positive developments of Photovoltaic energy increse the importance of reference Solar Cells. There is a substantial demand by the manufactureres, customers, research laboratories etc. to determine the actual efficiency of photovoltaic systems by means of accurately calibrated reference cells. They arealso used for quality assurance, monitoring as well as for the comparison and assessment of different devices and technologies,Solar cells and PV moduels can routinely be calibrated at industrial level innatural or simulated solar radiation against a reference device which matches the tet device both spectrally and geometrically/opically as closely as possible (Secondary calibration). Comparative picture will be presented for standard reference and secondary reference silicon solar cells. Also merits and demerits of outdoor and indoor calibrations at AM 1.5 spectrum of intensity 100 mw cm^-2 will be highlighted. Finally calibration methods of Solar Panels will be described in brief.

7 illus, 2 tables, 10 ref

011696   Biswal S;Pradhan M (Department of Physics, Nayagarh College, Nayagarh-752 069) : Magnetohydrodynamic unsteady free convection flow past an infinite plate with constant suction and heat sinks including dissipative heat. Acta Cienc Indica-Phys 2002, 28(4), 231-43.

An analysis of magnetohydrodynamic unsteady free convective flow of viscous fluid past an infinite plate has been carried out under the following conditions : (i) constant suction, (ii) presence of heat sinks, (iii) heat transfer with the consideration of dissipation. Approximate solutions have been derived for the mean velocity and temperature fields, the transient velocity and temperature fields, the skin-friction and the rate of heat transfer with their amplitudes and phases. Velocity and temperature distributions have been shown graphically, whereas the values of the skin-friction and the rate of heat transfer have been entered in tables. It is observed that the external transverse magnetic field and the heat absorbing sink influence the flow field and temperature field to a great extent.

8 illus, 4 tables, 13 ref

011695   Bhattacharjee B;Ganguli D;Lakoubovski K; Stesmans A;Chaudhuri S (Materials Science Dep, Indian Association for the Cultivation of Science, Kolkata-700 032) : Syntheisis and characterization of sol-gel derived ZnS : Mn<. Bull Mater Sci 2002, 25(3), 175-80.

Synthesis and characterization of undoped and Mn²⁺ doped ZnS nanocrystallites (radius 2-3 nm) embedded in a partially densified silica gel matrix are presented. Optical transmittance, photoluminescence (PL), ellipsometric and electron spin resonance measurements revealed manifestation of quantum size effect. PL spectra recorded at room temperature revealed broad blue emission signal centred at <126> 420 nm and Mn²⁺ related yellow-orange band centred at <126> 590 nm while ESR indicated that Mn in ZnS was present as dispersed impurity rather than Mn cluster.

10 illus, 23 ref

011694   Banerjee A;Haldar A K;Mondal J;Sen A;Maiti H S (Electroceramics Section, Central Glass and Ceramic Research Institute, Kolkata-700 032) : Bi-layer functionally gradient thick film semiconducting methane sensors. Bull Mater Sci 2002, 25(6), 497-9.

Gas sensors based on metal oxide semiconductors like tin dioxide are widely used for the detection of toxic and combustible gases like carbon monoxide, methane and LPG. One of the problems of such sensors is their lack of sensitivity, which to some extent, can be circumvented by using different catalysts. However, highly reactive volatile organic compounds (VOC) coming from different industrial an ddomestic products (e.g. paints, lacquers, varnishes etc) can play havoc on such sensors and can give rise to false alarms. Any attempt to adsorb such VOCs (e.g.by using activated charcoal) results in sorption of the detecting gases (e.g.methane) too. To get round the problem, bi-layer sensors have been developed such tin oxide based functionally gradient bi-layer sensors have different compositions at the top and bottom layers.

4 illus, 10 ref

011693   Arun P;Gaur N (Department of Physics Astrophysics, University of Delhi, Delhi-110 007) : How Simple is Simple Pendulum?. Phys Educ 2002, 19(3), 185-91.

Explains as to why some precautions are taken up and what will happen if the same are relaxed.

7 illus

011692   Angadi B;Jali V M;Lagare M T;Kini N S;Umarji A M (Physics Dep, Gulbarga University, Gulbarga-585 106) : Synthesis and thermal expansion hysteresis of Ca_1-xSr_xZr₄P₆O₂₄. Bull Mater Sci 2002, 25(3), 191-6.

The low thermal expansion ceramic system, Ca_1-xSr_xZr₄P₆O₂₄ for the compositions with x=o, 0.25, 0.50, 0.75 and 1 was synthesized by solid-state reaction. The sintering characteristics were ascertained by bulk density measurements. The fracture surface microstructure examined by scanning electron microscopy showed the average grain size of 2.47 μm for all the compositions. The thermal expansion data for these ceramic systems over the temperature range 25-800°C is reported. The sinterability of various solid solutions and the hysteresis in dilatometric behaviour are shown to be related to the crystallographic thermal expansion anisotropy. A steady increase in the amount of porosity and critical grain size with increase in x is suggested to explain the observed decrease in the hysteresis.

4 illus, 2 tables, 21 ref

011691   Ali S T;Rao J V;Varma K S;Prakash T L (Centre for Materials for Electronics Technology (C-MET), , IDA Phase II, Cherlapally, HCL PO, Hyderabad-500 051) : Purification of cadmium up to 5N+ by cacuum distillation. Bull Mater Sci 2002, 25(6), 479-81.

Cadmium was refined by vacuum distillation, a technique suitable for low boiling and melting point materials, to remove the heavy and low vapour pressure impurities at ppm level. The detailed analysis of the purified CD as well as raw Cd was done by ICP-OES techniques for 27 impurity elements. Purification was carried out in an efficient high-yield cacuum distillation system designed and fabricated for purifying 3N+ purity indigenous cadmium to 5N+ (99.999%). Analysis confirmed the reduction of total impurity content from 134 ppm (3N7) for raw Cd to 3 ppm (5N7) upon vacuum distilled Cd. Te study shows that the analysis of impurities such as Fe, Mg and Ca are contributed from environmental effect, whereas impurities such as Pb, Bi, Ag, Ni, Cu, Zn and Tl require adaptation of elemental analysing technique to counter dilution effect. The Hg trace analysis can however be carried out by hydride generation techniques.

1 illus, 1 table, 5 ref

011690   Al-Share M (Department of Physics, Mutah University, Mutah-karak-Jordan) : Determination of the HCH bond angle of CH₃CN and CD₃CN molecules. Acta Cienc Indica-Phys 2002, 28(3), 133-6.

The interbond angle HCH of the ¹³C and ¹⁵N taged isotopes of CH₃CN and CD₃CN has been determined within an accuracy of 5 x 10^-4 degree. The average value for all isotopes was found to be 109.0619° which is in good agreement with the values reported in literature. The deviation between the values of HCH and DCD bond angle was found to be 0.0217°.

2 tables, 28 ref

010563   Xialing G (NO, , Beijing, 102413 China) : The R/D of high power proton accelerator technology in China. Pramana J Phys 2002, 59(6), 951-5.

In China, a multipurpose verification system as a first phase of our ADS program consists of a low energy accelerator (150 MeV/3 mA proton LINAC) and a swimming pool light water subritical reactor. The activies of HPPA technology related to ADS in China, which includes the intense proton ECR source, the RFQ accelerator and some other technology of HPPA are described.

4 illus, 11 ref.

010562   Weisser D C;Lobanov N R;Hausladen P A;Fifield L K;Wallace H J ;Tims S G;Apushkinsky E G (Department of Nuclear Physics, Australian National University, Canberra, ACT 0200 Australia) : Novel matching lens and spherical ionizer for a cesium sputter ion source. Pramana J Phys 2002, 59(6), 997-1106.

The beam optics of a multi-sample sputter ion source, based on the NEC MCSNICS, has been modified to accommodate cathode voltages higher than 5 kV and dispenses with the nominal extractor. The cathode voltage in Cs sputter sources plays the role of the classical extractor accomplishing the acceleration of beam particles from eV to keV energy, minimizing space charge effects and interactions between the beam and residual gas. The higher the cathode voltage, the smaller are these contributions to the emittance growth. The higher cathode voltage also raises the Child's law limit on the Cs current resulting in substantially increased output. The incidental focusing role of the extractor is reallocated to a deceration Einzel lens and the velocity change needed to match to the pre-acceleration tube goes to a new electrode at the tube entrance. All electrodes are large enough to ensure that the beam fills less than 30 of the aperture to minimize aberrations. The improvements are applicable to sputter sources generally.

10 illus, 2 ref.

010561   Vyas B M (Phys Dep, Sukhadia University, Udaipur313 001) : Study of ionospheric drift and anisotropy parameters from first and second order echoes over low latitude. Bull pure appl Sci-Sect D 2002, 21(2), 105-9.

Ionospheric drift observations have been carried out at a low latitude station, namely, Udaipur (Geo.Mag. Lat, 14.5° N), during the first and second order radiowaves reflection conditions from the ionosphere. The spaced fading records have been subjected to similar fade and full correlation methods of analysis. It is observed that on an average the result of second order echoes show the lower value of apparent and true drift speed. However, the random component is more observed is second multiples reflection conditions. apparent drift direction, true drift direction and size of ionospheric irregularities do not show any variation in their value in first and second order echoes case. The results are interpreted in the light of nature of HF ratio were reflection processes.

3 illus, 10 ref

010560   Vockenhuber C;Golser R ;Kutschera W;Priller A;Steier P;Winkler S;Liechtenstein V (NO, Institute for Isotopic Research and Nuclear Physics University of Vien, Vienna, Australia) : Accelerator mass spectrometry of the heaviest long-lived radionuclides with a 3-MV tandem accelerator. Pramana J Phys 2002, 59(6), 1041-51.

A 3-MV pelletron tandem accelerator is the heart of the Vienna environmental research accelertor (VERA). The original design of the beam transport components allows the transport of ions of all elements, from the lightest to the heaviest. For light ions the suppressionof neighboring masses was sufficient to measure isotopic ratios of ¹⁴C/¹²C and ²⁶ AI/²⁷ AI as low as 10^-15 and ¹⁰ Be/⁹Be down to 10^-13. To suppress neighboring masses for the heaviest radionuclides in the energy range of 10-20 MeV, the resolution of VERA was increased both by improving the ion optics of existing elements at the injection side and by installing a new high-resolutionelectrostatic separator at the high-energy side. Interfering ions which pass all beam filters are identified with a Bragg-typ ionization detector and a high -resolution time-of-flight system. Two ultra-thin diamond-like carbon (DLC) foils are used in the start and stop detector, which substantially reduces losses due to beam straggling. This improved set up enables us to measure even the heaviest long-lived radionuclides, where stable isobraic interferences are absent (e.g. ²³⁶U and ²⁴⁴Pu), down to environmental levels. Moreoever, the advantage of a 'small' and well manageable machine like VERA lies in its higher stability and reliability which allows to measure these heavy radionuclides more accurately, and also a large number of samples.

6 Illus, 14 Ref.

010559   Venugopalan K;Lakshmi N (Phys Dep, M L Sukhadia Uinversity, Udaipur-313 001) : Hyperfine interactions studies on some ternary Fe-Based alloys. Bull pure appl Sci-Sect D 2002, 21(2), 139-42.

Three Fe-based ternary alloys, Fe₂CrSb, Fe₂MnAl and Fe₂TaAl were prepared and studied using Fe-57 Mossbauer spectroscopy. the Mossbauer spectra show that these alloys were poly-phased with only Fe₂CrSb showing cobic structure.

1 illus, 1 table, 8 ref

010558   U[adjuau P N;Yogendra Kumar;Nilima Kumari; Arvind Kumar (Dep of Physics, Nalanda Mahila College, ) : An analysis on the π<. Acta Cienc Indica-Phys 2002, 28(2), 79-80.

Presents some results on the study of the background level in the η' (958) mass region.

1 illus, 3 ref

010557   Upadhyay P N;Prakash R;Kumari N (Phys Dep, Nalanda Mahila College, Biharsharif-803 101) : Neutral Decay mode of the φ (1020) meson. Acta Cienc Indica-Phys 2002, 28(2), 81-2.

An account of the results of the φ→ all neutral decay mode has been presented here. The absence of an enhancement is attributed mainly to low branching ration of the φ of meson.

1 illus, 5 ref