Size and temperature induced phase transition behaviors of barium titanate nanoparticles
Size and temperature induced phase transition behaviors of barium titanate nanoparticles
复制标题
DOI：
10.1063/1.2179971
复制
发表时间：
2006-03-01
影响因子：
3.2
通讯作者：
Yashima, M
中科院分区：
文献类型：
--
作者：
Hoshina, T;Kakemoto, H;Yashima, M
采用草酸钛钡两步热分解和后处理法制备了密度高、几乎无杂质、无缺陷、粒径在20 ~ 1000 nm的钛酸钡（BaTiO3）细颗粒。利用同步辐射x射线衍射仪（XRD）研究了这些颗粒的晶体结构与尺寸和温度的关系。结果表明，尺寸诱导的铁电相变（四方-立方）发生在30nm左右。此外，晶体结构的温度依赖性表明，135℃时的一种相变随着晶粒尺寸的减小而分化为两种相变行为，即在135℃时，无论晶粒尺寸大小，四方立方相变温度都是恒定的，而胞体膨胀温度随着晶粒尺寸的减小而向低温转移。此外，拉曼散射光谱的温度依赖性表明，在阻尼因子不连续变化时的温度与XRD测量的电池体积膨胀温度基本一致。这些结果表明，纳米BaTiO3的相变行为与BaTiO3单晶的相变行为有很大的不同。
High density, almost impurity-free and defect-free barium titanate (BaTiO3) fine particles with various sizes from 20 to 1000 nm were prepared by the two-step thermal decomposition of barium titanyl oxalate and postheating treatment. The crystal structures of these particles were investigated as a function of the size and the temperature using synchrotron radiation x-ray diffraction (XRD) measurement. As a result, the size-induced ferroelectric (tetragonal-cubic) phase transition observed at around 30 nm. Moreover, the temperature dependence of the crystal structures revealed that one phase transition at 135 degrees C separated into two kinds of phase transition behaviors with decreased particle sizes, i.e., the tetragonal-cubic phase transition temperature was constant at 135 degrees C despite particle sizes while the cell volume expansion temperature shifted to low temperature with decreasing particle sizes. Moreover, the temperature dependence of Raman scattering spectra clarified that the temperature at a discontinuous change of damping factor was almost consisted with the cell volume expansion temperature from the XRD measurement. These results suggested that the phase transition behavior of the BaTiO3 nanoparticles was quite different from that of the BaTiO3 single crystals.