NOPR Collection:

Absolute hardness of carbazole doped anthracene single crystals by Vickers’ indentation

Fri, 01 Jun 2001 00:00:00 GMT

Title: Absolute hardness of carbazole doped anthracene single crystals by Vickers’ indentation Authors: Yagnik, J H; Vaidya, Nimisha; Shah, B S Abstract: The absolute hardness value of carbazole doped anthracene has been obtained using the Vickers’ hardness technique. The absolute hardness value is defined as the hardness which is independent of load. The results by graphical analysis do not compare well as in the case of pure anthracen³. The extrapolation function method has been employed. Page(s): 411-412

Effect of temperature on lyoluminescence of divalent impuriy doped sodium chloride

Fri, 01 Jun 2001 00:00:00 GMT

Title: Effect of temperature on lyoluminescence of divalent impuriy doped sodium chloride Authors: Chourasia, Bhawna; Khare, P K; Chandra, B P Abstract: The effect of temperature on the lyoluminescence (LL) of divalent impurity doped sodium chloride has been reported. When the NaCl crystallites irradiated using ⁶⁰Co source are dissolved in distilled water, initially the LL intensity increases with time, attains a maximum value, then it decreases and finally disappears. The peak l_m, of LL intensity versus time curve initially increases with temperature, attains an optimum value at a particular temperature and then it decreases with further increase in temperature. However, the total intensity I_T and time t_m, corresponding to the peak of LL intensity versus time curves decrease with increasing temperature of the solution. The peak intensity l_m, is maximum at a particular temperature because of the competition between increase in rate of dissolution of NaCl with temperature and decrease in efficiency η and density of F-centres with temperature. The value of time t_m, decreases with increasing temperature of the solution because of the increasing rate constant for the recombination of hydrated electrons with holes. The efficiency η and n_F decrease with temperature and therefore, the total intensity I_T decreases with increasing temperature of the solution. The decay time τ depends inversely on the rate of dissolution α, of solute in the solvent. Since α increases with increasing temperature of the solution, τ decreases with increasing temperature of the solution. Page(s): 392-396

Impedance spectroscopic analysis of nanophase Ag₂HgI₄ and Ag₂HgI₄-Al₂O₃ nanocomposites

Fri, 01 Jun 2001 00:00:00 GMT

Title: Impedance spectroscopic analysis of nanophase Ag₂HgI₄ and Ag₂HgI₄-Al₂O₃ nanocomposites Authors: Potty, S Sankara Narayanan; Khadar, M Abdul Abstract: Nanoparticles of Ag₂HgI₄have been prepared by chemical precipitation. The average particle size has been determined from x-ray line broadening. Grain and grain boundary contributions to the electrical conductivity of nanophase Ag₂HgI₄ and Ag₂HgI₄- Al₂O₃ nanocomposites are analyzed using impedance spectroscopy. The variations of these contributions with temperature and with the weight percentage of nano alumina are determined. The grain boundary conduction has been found to be less than the grain conduction in all the samples. The enhanced impedance of grain boundaries are attributed to the grain boundary properties of nanophase materials and the microsize space charge effects. Page(s): 366-372

On performance of pump current modulated charge pump PLL

Fri, 01 Jun 2001 00:00:00 GMT

Title: On performance of pump current modulated charge pump PLL Authors: Hati, A; Sarkar, B C Abstract: Since the performance of a charge pump PLL (CP-PLL) is strongly influenced by the pump current magnitude in the pump ON interval, this paper examines the effect of linearly increasing pump current on the transient response of the CP-PLL. It has been established through the numerical solution of the system equation and a simulation experiment using MAT-LAB software, that the process of pump current ‘‘modulation’’ may be used to enhance the transient behaviour of the CP-PLL. Page(s): 404-410

NOPR Collection:

Absolute hardness of carbazole doped anthracene single crystals by Vickers’ indentation

Effect of temperature on lyoluminescence of divalent impuriy doped sodium chloride

Impedance spectroscopic analysis of nanophase Ag2HgI4 and Ag2HgI4-Al2O3 nanocomposites

On performance of pump current modulated charge pump PLL

Impedance spectroscopic analysis of nanophase Ag₂HgI₄ and Ag₂HgI₄-Al₂O₃ nanocomposites