Neutron scattering study of ferroelectric Sn2P2S6 under pressure

Article

关键词: PHASE-TRANSITION;    UNIAXIAL FERROELECTRICS;    HYDROSTATIC-PRESSURE;    PHONON INTERACTIONS;    CRYSTAL-STRUCTURE;    CRITICAL-BEHAVIOR;    SOLID-SOLUTIONS;    ORDER-DISORDER;    SOFT MODES;    TEMPERATURE;   

DOI  :  10.1103/PhysRevB.86.224106

来源: SCIE

【 摘 要 】

Ferroelectric phase transition in the semiconductor Sn2P2S6 single crystal has been studied by means of neutron scattering in the pressure-temperature range adjacent to the anticipated tricritical Lifshitz point (p approximate to 0.18 GPa, T approximate to 296 K). The observations reveal a direct ferroelectric-paraelectric phase transition in the whole investigated pressure range (0.18-0.6 GPa). These results are in a clear disagreement with phase diagrams assumed in numerous earlier works, according to which a hypothetical intermediate incommensurate phase extends over several or even tens of degrees in the 0.5 GPa pressure range. Temperature dependence of the anisotropic quasielastic diffuse scattering suggests that polarization fluctuations present above T-C are strongly reduced in the ordered phase. Still, the temperature dependence of the ((2) over bar 00) Bragg reflection intensity at p = 0.18 GPa can be remarkably well modeled assuming the order-parameter amplitude growth according to the power law with logarithmic corrections predicted for a uniaxial ferroelectric transition at the tricritical Lifshitz point.

【 授权许可】

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