We report the single-crystal X-ray analysis of the structure of the pyrochlore oxide superconductor KOs2O6. The structure was identified as the β-pyrochlore structure with space group and lattice constant at : the K atom is located at the 8b site, not at the 16d site as in conventional pyrochlore oxides. We found an anomalously large atomic displacement parameter at for the K cation, which suggests that the K cation weakly bound to an oversized Os12O18 cage exhibits intensive rattling, as recently observed for clathrate compounds. The rattling of A cations is a common feature in the series of β-pyrochlore oxide superconductors AOs2O6 (A=Cs, Rb and K), and is greatest for the smallest K cation. 相似文献
The two double perovskite oxides Sr2AlSbO6 and Sr2CoSbO6 were prepared and their structures studied with the X-ray powder diffraction method. At room temperature the crystal structure of Sr2AlSbO6 is cubic , with . It was found that depending on the preparation conditions, the Al3+ and Sb5+ cations can be either entirely or partially ordered. In the case of the partially ordered Sr2AlSbO6 sample, the extension of cation ordering was estimated from the -dependent broadening of the diffraction peaks and the results were interpreted as evidence of the formation of anti-phase domains in the material. Low-temperature Raman spectroscopic measurements demonstrated that the cubic phase of Sr2AlSbO6 is stable down to 79 K.The room-temperature crystal structure of Sr2CoSbO6 is trigonal (space group with and . At 470 K, however, the material undergoes a continuous phase transition and its structure is converted to cubic (space group . The studied Sr2CoSbO6 sample was partially ordered, but unlike Sr2AlSbO6, no indication of the formation of anti-phase domains was observed. 相似文献
By the use of TG—MS, the thermal dissociation of anhydrous CuSO4 and Al2(S04)3 was found to proceed according to the reactions: followed by the reactions: No SO3 was indicated in the dissociation of alunite. The sulfate ion appears to dissociate by at least two different mechanisms although the parameter which controls the mechanisms has not been elucidated. 相似文献
Boiling intensifies the radiolytic conversion of diglyme since it stimulates the cleavage of the C–O bonds in the excited molecules and the primary radical cations, enhances the radical exchange reactions, and weakens the diglyme regeneration reactions.
