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

The precise crystal structure of Y1-xCaxTiO3 (x = 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 T-mono 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. (c) 2006 Elsevier B.V. All rights reserved.