Cubic perovskite polymorph of strontium metasilicate at high pressures

Abstract

By using a diamond-anvil cell (DAC) with laser heating technology, a cubic perovskite polymorph of SrSiO 3 has been synthesized at ∼38 GPa and 1500-2000 K for the first time. The P-V data of this new phase give ambient temperate elastic constants of V 0 = 49.18(5) Å 3 , K 0 = 211(3) GPa, respectively, when they are fitted against the Birch-Murnaghan equation of state with a fixed K 0 ′ at 4. On decompression, the SrSiO 3 cubic perovskite phase becomes unstable at ∼6.2 GPa and disappears completely at ∼4.7 GPa. The transformed product can be considered as an amorphous phase with a minor amount of small sized crystals in the amorphous matrix. First principle calculations predicted structural properties of both the cubic and the six-layer-repeated hexagonal perovskite polymorphs of SrSiO 3 in good agreement with experimental results. The experimental and theoretical results indicate that the larger Sr 2+ cation can substitute the Ca 2+ cation and enter into the lattice of the cubic perovskite phase of CaSiO 3 at lower mantle conditions with only a small lattice strain. These results indicate that Sr can be hosted in cubic perovskite CaSiO 3 found as inclusions in diamonds originating from the lower mantle.

Structural Relaxation of Oxide Compounds from the High-Pressure Phase

“…, Sr 2+ , and Ba 2+ cations are stabilized as hexagonal and/or cubic forms under high pressure [34][35][36][37][38]. These transformations have been confirmed by high-pressure experiments.…”

“…Therefore, expansion of the A-site cations disrupts the framework and makes the structure amorphous. Amorphization of the cubic perovskite structure has also been observed for SrSiO 3 [38] and BaSiO 3 [46]. Considering the structural similarity, the hexagonal perovskite structures could become amorphous during decompression.…”

High-temperature order–disorder phase transition in nacaphite, Na2CaPO4F

“…Experimental studies of phase transitions in minerals with perovskite-type structures continue to attract considerable attention due to their importance for the understanding of behavior of mineral matter subjected to the effects of high temperature and pressure in the deep Earth geospheres (Xiao et al 2012(Xiao et al , 2013Knight et al 2014Knight et al , 2015. A particular class of perovskite-related materials are antiperovskites, where cations and anions are interchanged so that perovskite-type units are built from anion-centered instead of cation-centered octahedra (Mitchell 2002).…”

Lattice Parameters, Electronic, and Magnetic Properties of Cubic Perovskite Oxides ARuO3 (A=Sr, Rb): A First‑Principles Study

“…Cubic perovskites (ABO3) have been studied extensively in the last two decades. For example, Xiao et al [6] reported lattice parameters between 3.50 and 3.61 Å for SrSiO3. Tariq et al [7] theoretically computed lattice parameters between 3.80 and 3.85 Å for cubic perovskites of SrAO3 (A = Cr, Fe, and Co).…”