Synthesis Of Nano Bismuth Ferrite Multiferroics By Microcontroller Based Thermogravimetric Analyzer

Microcontroller based thermogravimetric analyzer (MTGA) is an home built technique used to study the thermal decomposition of inorganic solids, chemical properties of intermediate and final products, synthetic conditions and synthesis of nanomaterials. The MTGA has additional features like controlled gas delivery system suitable for synthesis of nanomaterials in various gas atmospheres. This paper reports characterization of nano bismuth ferrite-BifeO3 (BFO) synthesized by MTGA. The MTGA system has been calibrated for BFO precursors. The variation in mass of redox mixture (metal nitrates and gylcene) with respect to temperature (thermogram) reveal the ideal conditions for the preparation of nano BFO by different techniques. It was found that structural and electrical results of BiFeO3 synthesized by MTGA are in good agreement with that prepared by other techniques like solution combustion method, sol-gel method, Pechini method, sonochemical method, hydrothermal method etc. The microcontroller based thermogravimetric analyser is one of the good techniques for the preparation of nanomaterials in different gas atmaspheres

Characterization of Al2O3 thin films prepared by spray pyrolysis method for humidity sensor

Al2O3 thin films were deposited on silicon, steel and nickel substrates to fabricate MOS and MIM devices. The films were prepared by spray pyrolysis method using a spray solution of Aluminium acetyl acetonate dissolved in dimethyl formamide and this solution was sprayed on to the hot substrates at temperatures of 300 and 350 °C. The films were amorphous in nature as detected by XRD. Capacitance versus voltage (C-V), current versus voltage (I-V) and capacitance versus frequency (C-f) measurements were taken for these films. MOS capacitor was used as a humidity sensor using the home made humidity sensor setup. ac capacitance and parallel resistance of the capacitor as a function of humidity were studied. It was found that the capacitance value increases from 0.537 to 2.073 nf with the increase in relative humidity (RH) from 0 to 90 and the resistance decreases from 153 to 93 kΩ with the increase in relative humidity from 20 to 87. Relative dielectric constant versus temperature measurements were done for the MOS device to check its ferroelectric behavior and its critical temperature was found to be around 66 °C. MIM device was also used as a humidity sensor by measuring capacitance as a function of time by keeping the sensor in a dessicator. The 555 timer circuits were used to check the sensor behavior of the MOS device. Volume resistivity and breakdown electric field of the film deposited on steel were measured and found to be 5 à 1011 Ω cm and 5 MV/cm, respectively. © 2006 Elsevier B.V. All rights reserved

Contribution of NIEL for gain degradation (β) in Si8+ ion irradiated silicon power transistor

The concept of non-​ionizing energy loss (NIEL) has been found useful for characterizing displacement damage defects in materials and devices. When NPN power transistors (2N6688 manufd. by BEL, India) are exposed for 110 MeV Si8+ ion irradn. in the fluence range 5 × 109 to 1 × 1013 ions cm-​2 at room temp. (300 K) and at liq. nitrogen temp. (77 K) cause functional failure due to surface and bulk defects. The output collector characteristics are studied as a function of total ionizing dose (TID) and total displacement damage dose (Dd) obtained using TRIM Monte Carlo code. It is obsd. that the shift in the output satn. voltage is considerably less for heavy ion irradn. compared to lighter ions like lithium ion irradn. The gain of the transistor degrades with ion irradn. Base reverse biased leakage current (BRBLC) increases with increase in ion fluence. The obsd. results are almost independent of the irradn. temp. These studies help to improve the device fabrication technol. to make Radiation Hard Devices for advanced applications

Magnetic studies of Bi x Y3-x Fe5O12 fabricated using conventional method

A series of Bi substituted yttrium iron garnet (Bi-YIG) nanoparticles with nominal formula of BixY3 − xFe5O12 in which x varied in steps of 0.0, 0.25 and 0.5 are prepared by conventional method. Vibration sample magnetometer (VSM) at Room temperature (RT) shows saturation magnetization decreases from 27.4 to 25.2 (emu/g) as x value increases from 0.0 to 0.5. Room temperature 57Fe Mössbauer spectra are recorded for these series. The hyperfine field value for octahedral and tetrahedral of samples increases from 484 and 390 kOe to 491 and 397 kOe respectability, as Bi replaces Y in (BixY3 − xFe5O12) atom with increasing x value. The effect of Bi3 +  substitution for Y3 +  on lattice constants, morphology and magnetic properties of pure YIG has been investigated

Relation between sedimentary layer thickness and fundamental frequency of the H/V spectra for Bangalore city

Soil amplification and topographical effects play a major role in earthquake damage to civil structures. Study of sedimentary layer thickness and behaviour under stress cycles is crucial for earthquake hazard analysis. Borehole logs for Bangalore are used to benchmark the relation between sedimentary thickness and resonant frequency of the soil layer for this region. Microtremor measurements are carried out at the locations where borehole drilling was done and the frequencies corresponding to spectral peaks of the H/V ratio are estimated, where H and V denote the horizontal and vertical spectral component of the microtremor displacement respectively. The thicknesses of the soil layer (D), obtained from borehole logs and the soil layer resonant frequencies (fr) determined from the H/V spectral peaks are used to obtain a regression relation between them. The regression relation obtained is given by D = (58.29 ± 8.8) � fr -(0.95±0.1)·Using the data from the work of Divya et al., a similar regression relation is plotted. The results obtained arein agreement with the field data. This relation can be used for computing the depth to the bedrock for Bangalore using microtremor survey at a location where borehole data is not available

The 3s Proton Occupancy in 206-Pb

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Test of the DWBA Description of Transfer Reactions at Intermediate Energies by Measuring a Complete Set of Single Nucleon and Elastic Scattering Data

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

A modular focal plane detector system for the heavy ion reaction analyzer at NSC, New Delhi

A detector system has been developed for the focal plane of the HIRA. It consists of two independent detectors, a low-pressure multiwire proportional counter (LP-MWPC) followed by a split-anode ionization detector. Details of the design and test results are presented. Using slow preamplifiers, the position resolution is ≥1 mm and the time resolution is estimated to be 1.5 ns for the LP-MWPC. The ionization detector gives 2.4% energy resolution for 150 MeV 28Si scattered off a gold target and the ΔZ/Z obtained for 28Si+27Al is 1/42 for Z=14. Some results for fusion and transfer studies for the 48Ti+58Ni and 28Si+68Zn systems, respectively, at energies around the Coulomb barrier, are presented to highlight the performance of the detector system

Transfer measurements for the Ti plus Ni systems at near barrier energies

Large enhancements have been observed in the sub-barrier fusion cross sections for Ti + Ni systems in our previous studies. Coupled channel calculations incorporating couplings to 2(+) and 3(-) states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer were carried out for Ti-46,Ti-48 + Ni-64 systems. The present paper gives the results of these studies