High-Pressure High-Temperature Stability and Thermal Equation of State of Zircon-Type Erbium Vanadate.

Author(s) Ruiz-Fuertes, J.; Martínez-García, D.; Marqueño, T.; Errandonea, D.; MacLeod, S.G.; Bernert, T.; Haussühl, E.; Santamaría-Pérez, D.; Ibáñez, J.; Mallavarapu, A.; Achary, N.; Popescu, C.; Bettinelli, M.
Journal Inorg Chem
Date Published 2018 Nov 05

The zircon to scheelite phase boundary of ErVO has been studied by high-pressure and high-temperature powder and single-crystal X-ray diffraction. This study has allowed us to delimit the best synthesis conditions of its scheelite-type phase, determine the ambient-temperature equation of state of the zircon and scheelite-type structures, and obtain the thermal equation of state of the zircon-type polymorph. The results obtained with powder samples indicate that zircon-type ErVO transforms to scheelite at 8.2 GPa and 293 K and at 7.5 GPa and 693 K. The analyses yield bulk moduli K of 158(13) GPa for the zircon phase and 158(17) GPa for the scheelite phase, with a temperature derivative of d K/d T = -[3.8(2)] × 10 GPa K and a volumetric thermal expansion of α = [0.9(2)] × 10 K for the zircon phase according to the Berman model. The results are compared with those of other zircon-type vanadates, raising the need for careful experiments with highly crystalline scheelite to obtain reliable bulk moduli of this phase. Finally, we have performed single-crystal diffraction experiments from 110 to 395 K, and the obtained volumetric thermal expansion (α) for zircon-type ErVO in the 300-395 K range is [1.4(2)] × 10 K, in good agreement with previous data and with our experimental value given from the thermal equation of state fit within the limits of uncertainty.

DOI 10.1021/acs.inorgchem.8b01808
ISSN 1520-510X
Citation Inorg Chem. 2018;57(21):1400514012.

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