Phase relations and equation of state of ZrO₂to 100 GPa

Abstract

The phase relations and equation of state of ZrO 2 were investigated up to 100 GPa by means of in situ observation using laser heating in a diamond anvil cell and synchrotron radiation. A cotunnite (PbCl 2 )-type phase, which appears above 12.5 GPa, is stable to a pressure of 100 GPa and a temperature of 2500 K. No post-cotunnite phase was observed under the present experimental conditions. The unit-cell parameters and the volumes of the cotunnite-type ZrO 2 were determined as a function of pressure at room temperature using a laser-annealing technique. The cotunnite-type ZrO 2 shows rather isotropic compression. The bulk modulus calculated using the Birch-Murnaghan equations of state is 278 GPa, which suggests that high-density ZrO 2 is a candidate for potentially very hard materials. In situ high-temperature experiments performed below 12.5 GPa revealed that a tetragonal fluorite (CaF 2 )-type phase is stable up to 3000 K, although a cubic fluorite-type phase has been assumed to exist in this high-temperature regime. The result suggests the possibility that stoichiometric ZrO 2 does not show the cubic structure up to the melting temperature.

Effect of Annealing on the Crystal Structure and Microstructure of Pr Doped ZrO2-Y2O3Nanocrystals

“…• C. At high pressure, the monoclinic ZrO 2 transforms to orthorhombic phases (OrthoI: space group P bca, OrthoII: space group P nma) [12]. Annealing of bulk monoclinic zirconia, in agreement with the phase diagram (see e.g.…”

“…Ref. [12]), leads to transformation to higher symmetry (T or C) phases. Both high-temperature polymorphs exhibit properties being advantageous for specific applications.…”

Thermally induced permittivity enhancement in La-doped ZrO2 grown by atomic layer deposition on Ge(100)

“…This value resembles the one expected for c-and is higher than the one of monoclinic ͑m-͒ZrO 2 ͑ϳ20͒, thermodynamically stable on Si͑100͒. 23,24 An active role in determining the of as-grown films might be played by the large ionic radius ͑i rad ϳ 1.23 Å͒ of La atoms, inserted into the ZrO 2 lattice, softening the ZrO 2 IRactive modes. 21,25 The intercept of the linear fit to the CET data confirms the presence of an IL between La-ZrO 2 and Ge͑100͒ and clarifies the higher values of La-ZrO 2 compared to the one of the stack.…”

Stability of the MgSiO3 analog NaMgF3 and its implication for mantle structure in super‐Earths

“…[14] The baddeleyite-type phase is normally found instead of pyrite type, with both of these phases transforming to the SrI 2 -type phase before transforming to cotunnite at higher P [Ohtaka et al, 2005]. However, systematic high resolution investigation of SiO 2 analogs at high temperature and quasihydrostatic conditions is lacking.…”