Structural phase transitions in CaSi2 under high pressure

P. Bordet, M. Affronte, S. Sanfilippo, M. Núñez-Regueiro, O. Laborde, G. L. Olcese, A. Palenzona, S. LeFloch, D. Levy, M. Hanfland

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Abstract

In situ x-ray-diffraction measurements under high pressure (P up to 20 GPa) have been used to study structural changes in the rhombohedral and the tetragonal phases of CaSi2 at room temperature. Lattice parameters of the tetragonal phase regularl̊y change with increasing pressure while the rhombohedral phase undergoes two structural phase transitions: A trigonal structure is observed for 9<P<16 GPa and a new AlB2-like phase appears for P>16 GPa. These observations lead to ascribe the appearance of superconductivity to the trigonal phase while the highest Tc's can be related to the transition towards the AlB2-like phase that differs from the low-pressure phases by the almost planar bonds of silicon.

Original languageEnglish
Pages (from-to)11392-11397
Number of pages6
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume62
Issue number17
DOIs
StatePublished - 1 Nov 2000
Externally publishedYes

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