Metal-insulator transition in Y1-xCaxTiO3Y1-xCaxTiO3 studied by X-ray scattering

The precise crystal structure of Y1-xCaxTiO3Y1-xCaxTiO3 (x=0.38x=0.38) has been investigated by the single crystal X-ray scattering. We have demonstrated the sequence of structural phase transitions, i.e. the high-temperature orthorhombic structure to monoclinic one (Mono) at TmonoTmono and the Mono to the low-temperature orthorhombic structure (LTO) at the lower temperature. It provides a strong evidence that the structural phase transition, LTO-Mono, is responsible for the metal-insulator (MI) transition, though the phase separation of LTO and Mono was reported to be the origin of the MI transition. The pressure–temperature phase diagram of the crystal structure was also determined to elucidate the relation between the MI transition and the LTO-Mono phase transition.