In-rich Phase Research Articles

Positron lifetime study of the β'-PdIn phase

Positron lifetime measurements on the ordered beta -Hume-Rothery phase of the alloy PdIn (B2 structure) and on Pd-rich and In-rich phases are reported. The samples were studied both in thermal equilibrium and after quenching. Constitutional defects (In-rich side) and antistructure atoms (Pd-rich side) were detected. The change of the lifetime as a function of composition is discussed.

Thermodynamic and mass transport properties of “LiIn”

The EMF of the vario-stoichiometric phase “LiIn” lies between 497 and 145 mV relative to pure lithium at 415°C over the composition range from 46.7 to 63.3 a/o Li, corresponding to a lithium activity varying from 2.29×10 −4 to 8.67×10 −2 at that temperature. On the Li-deficient side of LiIn, the chemical diffusion coefficient increases rapidly with decreasing lithium concentration, approaching the value of 3.98×10 −5 cm 2/sec near the In-rich phase boundary of “LiIn”. In the region of positive deviations from the ideal stoichiometry, the chemical diffusion coefficient remains essentially constant up to a composition about 57.8 a/o Li. At higher lithium concentrations, the chemical diffusion coefficient first decreases and then increases as more lithium is added to the sample, and shows a minimum value of 4.73×10 −7 cm 2/sec at 62.2 a/o Li.

Pressure-induced phase transformation in In 2Bi

We have made measurements of the pressure dependence of the superconducting transition temperature, T c , for In 2Bi and related alloys. For In 2Bi- phase alloys, a large discontinuity in T c is seen at 15–20 kbar, which we associate with a phase transformation first seen by Bridgman [1]. Our measurements suggest that this transformation is produced by the decomposition of In 2Bi into In 5Bi 3 and an In-rich phase. In the low pressure phase, T c shows a minimum at 9–15 kbar whereas it depends linearly on pressure in the high pressure phase with ϖ T c /ϖ P equal to -4.9 × 10 -5 K bar -1.