Synthesis and Properties of Sr 9 Ce 2 W 4 O 24 Quaternary Perovskite

We report details on the synthesis and properties of strontium cerium tungstate, Sr 9 Ce 2 W 4 O 24, a quaternary perovskite that has not yet been synthesized in pure form. Room-temperature powder X-ray diffraction (XRD) identified the most probable space group as tetragonal I 4 1 / a . X-ray photoelectron spectroscopy confirmed that the material obtained after synthesis contained cerium in both 3+ and 4+ charge states, as well as tungsten in 5+ and 6+ states. Temperature-dependent Raman and XRD measurements done at 1 atm air and N 2 excluded the possibility of a phase transition occurring within the 8–873 K; however, when exposed to air, the compound decomposes to a mixture of various salts and oxides just above 573 K. When compressed at room temperature, a possible transition toward lower-symmetry, monoclinic ( C 2/ c or C 2/ m ) space groups was detected between 12.5 and 15 GPa.