Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Rama...Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Raman spectroscopy.The pressure dependence of phonon modes up to 30GPa reveals two characteristic pressures:one is at around 4.6GPa which corresponds to the rhombohedral-to-tetragonal phase transition,showing that the pressure strongly suppresses the coupling between the off-centered A-and B-site cations;the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure∼13–15GPa with certain degree of order-disorder transition,evidenced by the abnormal changes of intensity and FWHM in Raman spectrum.展开更多
Refractive indices and extinction coefficients of O.92Pb（Mgl/3Nb2/3）O3-O.O8PbTiO^（PMN-O.OSPT） single crystaJ are investigated by variable angle spectroscopic ellipsometry （VASE） at different wavelengths. The par...Refractive indices and extinction coefficients of O.92Pb（Mgl/3Nb2/3）O3-O.O8PbTiO^（PMN-O.OSPT） single crystaJ are investigated by variable angle spectroscopic ellipsometry （VASE） at different wavelengths. The parameters relative to the energy band structure are obtained by fitting to the single-oscillator dispersion equation, and the band gap energy is also deduced from the Tauc equation. Similar to most oxygen-octahedra ferroelectries, PMN-O.OSPT has the same dispersion behavior described by the refractive-index dispersion parameters.展开更多
文摘通过溶剂热法制备Cd0.01Co0.79Cr0.8S2粉体。XRD、FESEM、TEM、纳米激光粒度分析表明制备的Cd0.01Co0.79Cr0.8S2是纳米级的粉体,颗粒细小、结晶良好,呈现简单立方结构。Cd0.01Co0.79Cr0.8S2粉体的比表面积为6.582 0m2/g,属于介孔材料。Cd0.01Co0.79Cr0.8S2在可见光区域透光率超过95%,禁带宽度为3.49 e V,电阻较大,体积电阻率为108!·mm,呈现较好的绝缘性。Cd0.01Co0.79Cr0.8S2在688 nm左右发射一个较强的红光带,显示了较好的荧光性能,有望在LED器件中获得应用。
基金Supported by the National Natural Science Foundation of China(Grant Nos.11674231,11974250,and 51772192)the Science and Technology Commission of Shanghai Municipality(Grant Nos.17070502700 and 19070502800)the Shenzhen Development and Reform Commission Foundation for Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressures.
文摘Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Raman spectroscopy.The pressure dependence of phonon modes up to 30GPa reveals two characteristic pressures:one is at around 4.6GPa which corresponds to the rhombohedral-to-tetragonal phase transition,showing that the pressure strongly suppresses the coupling between the off-centered A-and B-site cations;the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure∼13–15GPa with certain degree of order-disorder transition,evidenced by the abnormal changes of intensity and FWHM in Raman spectrum.
基金Supported by the National High-Tech Research and Development Program of China under Grant Nos 2008AA03Z410 and 2006AA03Z107, the National Natural Science Foundation of China under Grant Nos 60837003, 50777065 and 50602047, the Innovation Funds from Shanghai Institute of Ceramics of Chinese Academy of Sciences under Grant No SCX0608, and the Fund of National Engineering Research Center for Optoelectronic Crystalline Materials （2005DC105003） under Grant No 2007K05.
文摘Refractive indices and extinction coefficients of O.92Pb（Mgl/3Nb2/3）O3-O.O8PbTiO^（PMN-O.OSPT） single crystaJ are investigated by variable angle spectroscopic ellipsometry （VASE） at different wavelengths. The parameters relative to the energy band structure are obtained by fitting to the single-oscillator dispersion equation, and the band gap energy is also deduced from the Tauc equation. Similar to most oxygen-octahedra ferroelectries, PMN-O.OSPT has the same dispersion behavior described by the refractive-index dispersion parameters.
