Ferroelectric soft mode of polar ZnTiO3 investigated by Raman spectroscopy at high pressure

Article

关键词: GENERALIZED GRADIENT APPROXIMATION;    PHASE-TRANSITION;    THIN-FILMS;    LINBO3;    PEROVSKITE;    PHONONS;    1ST-PRINCIPLES;    DEPENDENCE;    LITAO3;    TEMPERATURE;   

DOI  :  10.1103/PhysRevB.91.214110

来源: SCIE

【 摘 要 】

We explore the vibrational behavior and stability of ferroelectric ZnTiO3 under high pressure by Raman spectroscopy and second-harmonic-generation (SHG) measurements. Ab initio lattice-dynamics calculations have been employed to solve a controversy concerning the phonon-dispersion relations of ZnTiO3 and to carry out an assignment of the Raman modes. A ferroelectric to paraelectric phase transition has been observed both by Raman spectroscopy and SHG at 20.8 GPa. Contrary to LiNbO3, the ferroelectric soft mode of ZnTiO3 has been found to be the A(1)(2) and not the A(1)(1) mode. The calculated eigenvectors show that the A(1)(2) mode of ferroelectric ZnTiO3 is an antiphase vibration of the Ti atom against the oxygen framework, similar to the soft modes observed in ferroelectric perovskites. The SHG signal of ZnTiO3 has been found to be independent of the grain size below the phase transition, indicating that ZnTiO3 is a phase-matchable compound.

【 授权许可】

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