Structural phase transitions in CaSi2 under high pressure
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 regularly 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.
- Publication:
-
Physical Review B
- Pub Date:
- November 2000
- DOI:
- 10.1103/PhysRevB.62.11392
- Bibcode:
- 2000PhRvB..6211392B
- Keywords:
-
- 61.50.Ks;
- 61.10.-i;
- 74.62.Bf;
- 81.30.Bx;
- Crystallographic aspects of phase transformations;
- pressure effects;
- X-ray diffraction and scattering;
- Effects of material synthesis crystal structure and chemical composition;
- Phase diagrams of metals and alloys