スピネル化合物AlV_2O_4における電荷秩序構造と不純物置換効果 Charge Ordered Structure and its Impurity Doping Effect in Spinel AlV_2O_4
The charge ordered (CO) state in spinel A1V<SUB>2</SUB>O<SUB>4</SUB>, 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 A1V<SUB>2</SUB>O<SUB>4</SUB> 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 A1V<SUB>2-x</SUB>Cr<SUB>x</SUB>O<SUB>4</SUB> with x=0.125.
日本結晶学会誌 48(6), 424-428, 2006-12-25
The Crystallographic Society of Japan