Y V G S Murti
Articles written in Bulletin of Materials Science
Volume 11 Issue 4 December 1988 pp 319-328
Results on the internal friction of disordered and partially ordered Cu0·81Pd0·19 alloy in the temperature range 160–300 K and frequency range 1–2 Hz are reported. All the peaks are classified into three groups. Two prominent peaks of the first group occurring between 180 and 200 K are observed only in completely disordered samples. A long annealing treatment removes these peaks. These peaks may be due to interaction of dislocations with preferentially clustered palladium atoms in the disordered alloy. A second group of peaks in the temperature range 210–270K is sensitive to the microstructure and are presumably related to dislocation-dislocation interactions. In partially ordered samples new peaks appear at between 210 and 285 K. Activation parameters of these peaks are presented.
Volume 20 Issue 4 July 1997 pp 435-440
Silver halide crystals AgCl and AgBr exhibit all the three types of intrinsic point defects, namely, cationic Frenkel disorder, Schottky disorder and the bound vacancy pair disorder. The ionic conductivity anomaly at high temperatures, the unusual behaviour in respect of self- and impurity diffusion and the contrasting features in the anion self-diffusion between AgCl and AgBr do not all satisfactorily fit into the prevailing models of ionic transport. We review these features critically. We also discuss the potential and polarization models used in the theoretical evaluation of the enthalpies of formation of the intrinsic defects in these crystals. Results of our recent investigations on these questions will be presented to highlight their implications to the defect physics of these materials.
Volume 20 Issue 4 July 1997 pp 451-454
We present new findings on the enthalpies of formation of vacancies and interstitial ion defects on either sublattice in the alkali halide crystals MX (X=F, Cl, Br and M=Li, Na) using the MPPI model. The model uses a minimum fit to crystal properties and is fully consistent with the dielectric response. The role of the non-Coulombic short range forces
Volume 20 Issue 4 July 1997 pp 579-582
Perfluoroethylene sulfonic acid polymer (NAFION) films are subjected to ion exchange in the medium of aqueous solutions of cadmium acetate, followed by ammonia passivation. The films are then treated with hydrogen sulfide gas for prescribed times. X-ray powder diffraction data of these samples have been analyzed for estimating the sizes of the nanocrystallites. The optical absorption spectra of the samples show an absorption edge beginning at 525 nm for the largest size clusters. A broad absorption band appears with a maximum around 410 nm–440 nm in the smaller size clusters.
Volume 45, 2022
Continuous Article Publishing mode
Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020
Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020
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