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Phase transitions of BaSi 2 at high pressures and high temperatures

1998; American Physical Society; Volume: 58; Issue: 18 Linguagem: Inglês

10.1103/physrevb.58.11922

1095-3795

Motoharu Imai, Toshiyuki Hirano, Takumi Kikegawa, Osamu Shimomura,

Rare-earth and actinide compounds

In situ x-ray diffraction measurements reveal that ${\mathrm{BaSi}}_{2}$ has three high-pressure, high-temperature phases: a trigonal, a cubic, and an additional phase, at pressures up to 7 GPa and temperatures up to 1300 K. The trigonal phase exists at lower temperatures than previously reported, and the additional phase appears in the pressure-temperature region reported as the trigonal region previously. The structures that appear at high pressures are the same as those at ambient conditions of the other alkaline-earth-metal disilicides with a smaller atomic number metal. This is different from structural sequence for pure elements or for ${\mathrm{AB}}_{2}$-type compounds such as dioxides of 4A group elements.