title: An x-ray scattering study of Sn2P2S6: absence of incommensurate phase up to 1 GPa.
abstract: The ferroelectric phase transition in a semiconductor Sn(2)P(2)S(6) single crystal has been studied by means of high-resolution synchrotron x-ray diffraction in the pressure-temperature range where an incommensurate modulated phase has been anticipated for many years. In contrast with the predictions, the present measurements reveal only a direct ferroelectric-paraelectric phase transition close to T = 100 K, p = 1.1 GPa. In the vicinity of this phase transition, a characteristic critical diffuse scattering was observed, but no satellite peaks could be resolved there. It is concluded that the earlier hypothesis about the presence of an incommensurate phase and associated Lifshitz point in the temperature-pressure phase diagram of Sn(2)P(2)S(6) is incorrect.
authors: Institute of Physics, Academy of Sciences of the Czech Republic, Praha 8, Czech Republic. ondrejkovic@fzu.cz
authors: P
authors: P
authors: Ondrejkovic
authors: M
authors: M
authors: Guennou
authors: M
authors: M
authors: Kempa
authors: Y
authors: Y
authors: Vysochanskii
authors: G
authors: G
authors: Garbarino
authors: J
authors: J
authors: Hlinka