La-,Ca-PbTiO_3纳米晶的结构和声子特性  

Structure of La-, Ca-PbTiO_3 nanocrystals and phonon characteristics

作　　者：邓昱[1] 张明生[1] 

机构地区：[1]南京大学物理系,固体微结构实验室江苏南京210093

出　　处：《微纳电子技术》2003年第7期529-530,535,共3页Micronanoelectronic Technology

基　　金：国家自然科学基金 (10 1740 3 4);江苏省自然科学基金 (BK2 0 0 10 2 6)资助项目

摘　　要：采用水热法制备了不同掺杂浓度的La PbTiO3(PLT)、Ca PbTiO3(PCT)纳米晶 ,平均粒径30nm。通过透射电境、X光衍射和拉曼散射对纳米晶的晶格结构和声子特性进行了研究。结果表明掺镧引起PbTiO3声子软化 ,相变温度降低 ,并导致晶格四方性减小 ,当掺镧浓度达到 15 %时 ,发生四方 立方相变 ;掺钙亦使PbTiO3四方性减小 ,但未引起声子软化及结构相变。我们认为PbTiO3纳米晶铅位掺杂引入多余电荷使Ti O杂化减弱 。PLT and PCT nanocrystals of various doping concentrations were prepared by hydrothermal technique, and the average grain size is 30 nm. Transmission electron microscope (TEM), Raman spectroscopy and X ray diffraction (XRD) were used to investigate the lattice structures, phonon properties of the samples. La doping lowers the phase transition temperature of PbTiO 3 nanocrystals, leading to the decrease of the tetragonality and softening behaviors of the phonons. A tetragonal cubic phase transition occurs when La concentration reaches 15%. While Ca doping decreases the tetragonality of PT without causing phonon softening and phase transition. We conclude that the charge introduced by doping might weaken the Ti O hybridization in PbTiO 3, which is the main cause of these doping effects.

关 键 词：水热法 La-PbTiO3 纳米晶 结构 声子特性 晶格结构 Ca-PbTiO3 

分 类 号：TB383[一般工业技术—材料科学与工程]