Articles written in Bulletin of Materials Science
Volume 2 Issue 3 August 1980 pp 207-216
Positron lifetime has been measured in SmS under external pressures from 0 to ∼ 16 kbar, and in (Sm0·8Gd0·2)S at temperatures from 10 K to 300 K. An abrupt drop in the lifetime was observed at the valence transition at a pressure of 6·5 kbar in SmS and at a temperature of ∼ 120 K in (Sm0·8Gd0·2)S. Measurement of the Doppler broadening of the annihilation photons was made in (Sm0·8 Gd0·2)S as a function of temperature. The line shape parameter of the Doppler broadened spectrum also showed an abrupt change at the transition. Angular correlation of annihilation photons was measured in the semiconducting phase of SmS and in the metallic phase of (Sm0·8Tb0·2)S. The correlation profile in the mixed valence (metallic) phase was broader than that in the semi-conducting phase. These results have been explained on the basis of the electronic structure of the semiconducting and the metallic phases of these materials.
Volume 9 Issue 1 March 1987 pp 21-27
Magnesium nickel hydride, Mg2NiH4, exists in two crystallographic modifications, the low temperature phase crystallizing in monoclinic structure and the high temperature phase having a cubic structure. The phase transition (∼510 K) was accompanied by a small composition change. The enthalpies and entropies of formation of these hydrides were calculated from the DTA data and compared with the values obtained by other methods.
Volume 15 Issue 3 June 1992 pp 213-217
The characteristics of materials like ferrites, garnets, ferroelectrics temperaturecompensated dielectrics and copper-coated PTFE-based composites, extensively used in microwave devices are discussed.
Volume 16 Issue 5 October 1993 pp 381-391
The oxygen content in YBa2Cu3O7-δ has been varied by substitution at Ba site with Sr or K and its influence on the structural and superconducting properties has been studied. These properties are compared with that of unsubstituted YBa2Cu3O7-δ prepared by quenching. The increase in
Volume 21 Issue 5 October 1998 pp 427-431 Positron Annihilation Studies
Time differential perturbed angular correlation (TDPAC) and positron life-time measurements on cold-worked and hydrogen charged
Volume 22 Issue 4 June 1999 pp 751-755 Oxide Materials
The effect of doping iron at the yttrium site in hexagonal KCaY(PO4)2 is studied for various concentrations of
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