A new triclinic modification of the pyrochlore-type KOS2O6 superconductor

A new modification of KOS2O6, the representative of a new structural type (Pearson symbol aP18, a = 5.5668(1)angstrom, b = 6.4519(2)angstrom, c = 7.2356(2)angstrom, alpha = 65.377(3)degrees, beta = 70.572(3)degrees, gamma = 75.613(2)degrees space group P-1, no. 2 was synthesized employing high pressure technique. Its structure was determined by single-crystal X-ray diffraction. The structure can be described as two OsO6, octahedral chains relating to each other through inversion and forming big voids with K atoms inside. Quantum chemical calculations were performed on the novel compound and structurally related Cubic compound. High-pressure X-ray study showed that cubic KOS2O6 phase was stable up to 32.5(2)GPa at room temperature. (C) 2008 Elsevier Inc. All rights reserved.