Ruiz-Fuertes, J., Martínez-García, D., Marqueño, T., Errandonea, D., MacLeod, S. G., Bernert, T., Ibanez, J., … Bettinelli, M. (2018). High-Pressure High-Temperature Stability and Thermal Equation of State of Zircon-Type Erbium Vanadate. Inorganic Chemistry, 57(21), 14005–14012. https://doi.org/10.1021/acs.inorgchem.8b01808
The zircon to scheelite phase boundary of ErVO4 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 ErVO4 transforms to scheelite at 8.2 GPa and 293 K and at 7.5 GPa and 693 K. The analyses yield bulk moduli K0 of 158(13) GPa for the zircon phase and 158(17) GPa for the scheelite phase, with a temperature derivative of dK0/dT = −[3.8(2)] × 10–3 GPa K–1 and a volumetric thermal expansion of α0 = [0.9(2)] × 10–5 K–1 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 (α0) for zircon-type ErVO4 in the 300–395 K range is [1.4(2)] × 10–5 K–1, in good agreement with previous data and with our experimental value given from the thermal equation of state fit within the limits of uncertainty.