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New high-pressure phase of GaAsO 4 : Implications for shape-memory materials

1995; American Physical Society; Volume: 51; Issue: 1 Linguagem: Inglês

10.1103/physrevb.51.38

1095-3795

S. M. Clark, Andrew G. Christy, Richard G. Jones, J. Chen, J. M. Thomas, G. Neville Greaves,

Crystal Structures and Properties

The effect of pressure on the crystal structure of ${\mathrm{GaAsO}}_{4}$ has been studied using energy-dispersive powder diffraction up to 19.7 GPa. A structural phase transition was observed between 6.3 and 9.5 GPa from the ambient hexagonal structure to a triclinic structure. A model for this new high-pressure phase is presented. The low- and high-pressure phases were found to have bulk moduli of 17.6 and 177.0 GPa, respectively. The phase transition is reversible and first order with a volume discontinuity of 8%. The implications for the related shape-memory materials are discussed.