Experimental and theoretical investigations on ThGeO4 at high pressure

Abstract

We report here the combined results of angle-dispersive x-ray diffraction experiments performed on ThGeO4 up to 40 GPa and total-energy density-functional theory calculations. Zircon-type ThGeO4 is found to undergo a pressure-driven phase transition at 11 GPa to the tetragonal scheelite structure. A second phase transition to a monoclinic M-fergusonite type is found beyond 26 GPa. The same transition has been observed in samples that crystallize in the scheelite phase at ambient pressure. No additional phase transition or evidence of decomposition of ThGeO4 has been detected up to 40 GPa. The unit-cell parameters of the monoclinic high-pressure phase are a = 4.98(2) A, b = 11.08(4) A, c = 4.87(2) A, and beta = 90.1(1), Z = 4 at 28.8 GPa. The scheelite-fergusonite transition is reversible and the zircon-scheelite transition non-reversible. From the experiments and the calculations, the room temperature equation of state for the different phases is also obtained. The anisotropic compressibility of the studied crystal is discussed in terms of the differential compressibility of the Th-O and Ge-O bonds.

arXiv comment24 pages, 5 figures, 2 tables

References in corpus (7)

• Pressure-induced alpha-to-omega transition in titanium metal: A systematic study of the effects of uniaxial stress
• Pressure effects on the structural and electronic properties of ABX4 scintillating crystals
• High-pressure structural study of the scheelite tungstates CaWO4 and SrWO4
• Determination of the high-pressure crystal structure of BaWO4 and PbWO4
• High-pressure x-ray diffraction study of SrMoO4 and pressure-induced structural changes
• High-pressure structural investigation of several zircon-type orthovanadates
• Landau theory applied to phase transitions in calcium orthotungstate and isostructural compounds

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