Thermal stability of osmium mixed oxides. IV. SrOsO 3 decomposition products. A new metastable SrOsO 4 phase

Abstract

The thermal decomposition of SrOsO 3 in a dynamic air flow has been studied using differential thermal analysis, thermogravimetry and X-ray powder diffraction. After decomposition above 920°C, a new phase was discovered, which has the formula SrOsO 4, a scheelite structure and tetragonal unit cell parameters a 0 = 5.422 Å, c 0 = 11.92 Å, Z = 4, space group I4 1/ a, and a pycnometric density of 6.46 g cm −3. Above 1030 ± 6°C, SrOsO 4 decomposes into SrO, osmium tetroxide and osmium metal.