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Scheelite CaWO 4 at high pressures

2003; IOP Publishing; Volume: 15; Issue: 43 Linguagem: Inglês

10.1088/0953-8984/15/43/010

1361-648X

Andrzej Grzechnik, Wilson A. Crichton, Michael Hanfland, Sander van Smaalen,

X-ray Diffraction in Crystallography

The high-pressure room-temperature behaviour of scheelite CaWO4 (I41/a,Z = 4) is studied using high-resolution synchrotron angle-dispersive x-ray powder diffraction in diamond anvil cells loaded with helium or a mixture of methanol and ethanol as the pressure-transmitting media. At about 10 GPa, there occurs a phase transition to the fergusonite type (I 2/a,Z = 4) without any discontinuity in the pressure dependence of the unit cell volumes. These observations are discussed in relation to the high-pressure–high-temperature systematics of the AMX4 and AX2 type compounds.