1. Condensed-Matter Physics & Materials Science Seminar

    "Growth and electric field induced phase transition in (Pb, La)(Zr, Sn, Ti)O{3} antiferroelectric single crystal near MPB"

    Presented by Qiang Li, Tsinghua University, China

    Tuesday, November 26, 2013, 1 pm
    Bldg. 734, ISB Conf. Rm. 201 (upstairs)

    Hosted by: Genda Gu

    As a novel candidate for electrical energy storage devices and smart materials, La modified perovskite antiferroelectric Pb(Zr,Sn,Ti)O3(PLZST) single crystal, with a composition near the morphotropic phase boundary(MPB), has been grown successfully from a PbO-PbF2-B2O3 flux in our lab, for its extinguished Ps and strain.[1] PbF2-evaporation-dependent was considered as mainly result of PLZST single crystal growth in PbO-PbF2-B2O3 flux.[2] Mass loss and growth produces investigations indicated that the compositions of as-grown crystal was strongly influenced, but could be adjusted by changing the ratio of starting materials. In order to understand the influence of phase structure on the polarization and phase transition behaviors, as-grown single crystal was studied by X-ray diffraction and dielectric properties analysis. It revealed that as-grown PLZST single crystal was antiferroelectric/ferroelectric (AFE/FE) phase coexistence with the AFE phase dominated at room temperature. Temperature-dependent polarization and strain measurements indicated the AFE phase could be induced into a metastable field-induced FE phase (FEin). The FEin phase could be maintained in the crystal below a critical temperature of 90℃ and recovered to AFE phase around this temperature, accompany with abrupt change in the field-induced strain. The largest strain at 90℃ was ten times larger than that at room temperature. Microstructure and domain of PLZST single crystal were studied by Raman and in situ polarized light microscope (PLM).[3,4] Polarization studies indicated that the dielectric and ferroelectric properties of PLZST single crystals were strongly orientation-dependent. And Ps along [111] direction was much higher than that of other else. Reference [1]. N.N. Luo, Y.Y. Li, Z.G. Xia, Q. Li, Progress in lead-based ferroelectric and antiferroelectric single crystals: composition modification, crystal growth and properties, CrystEngComm, 14(2012)4547 [2]. Y