2006 年 48 巻 6 号 p. 424-428
The charge ordered (CO) state in spinel A1V2O4, which appears below 700 K, was examined by electron and synchrotron x-ray diffraction experiments. It was found that the CO structure is characterized by the formation of V clusters (heptamers), each of which is consisting of 7 vanadium atoms and is in a spin-singlet state as a total. In addition, it was revealed that the Cr substitution for V in A1V2O4 suppressed the formation of the long-ranged CO structure and induced the charge disordered (CD) state. As a result, the coexisting state between the CO and CD states with the 20-30 nm size was stabilized in A1V2-xCrxO4 with x=0.125.