Effect of Ti Substitution on V–V Dimerization in Ilmenite-Type MgVO 3

The origin of V–V dimerization, a characteristic phenomenon observed in ilmenite-type vanadium oxides, remains unclear. To elucidate this origin, we must first clarify the conditions under which such dimers can form. Here, we investigate the effect of Ti 4+ substitution at the V 4+ sites in MgVO 3, a representative ilmenite-type vanadium oxide. Synchrotron X-ray diffraction measurements revealed that increasing the Ti content lowers the structural phase transition temperature associated with V–V dimerization. Furthermore, magnetic susceptibility measurements indicated that Ti substitution suppresses the formation of V–V bonds, which are disrupted concomitantly with the structural phase transition. MgV 0.70 Ti 0.30 O 3 adopts a rhombohedral ilmenite-type structure without long-range V–V dimer ordering even at low temperatures. This study provides experimental insights into the stability and collapse of V–V dimers.