Preparation of the smallest ferroelectric particle of barium titanate and the investigation of its transformation temperature

下面的市售钛酸钡粉末的目的是找出最小的四方颗粒的大小。酒井化学工业株式会社生产的水热钛酸钡；BT-01和BT-006的标称尺寸分别为100纳米和6纳米。KCM公司的另一种粉体，采用固态反应制得，其标称尺寸为700 nm。后一种粉末在室温下在1GPa条件下反复电激电泳，通过粉末x射线衍射、透射电镜和热容测量对其进行表征。CIPed一次粉末的幼崽转变焓为普通粉末的1/15。然而，经过60次CIPed后，晶体尺寸减小到47 nm，但仍呈四边形。此外，透射电镜还发现了由塌缩边界区和调制晶格阵列组成的扭曲和/或挤压织构。一些文献报道了BT-01的立方钛酸钡。然而，这项研究表明，所有的…更多的粉末是四方的，收到BT-01和BT-006，以及他们的加热样品。这一结论是由以下结果得出的，然而，即使非常仔细的电子衍射检查也未能在收到的BT-01粉末上检测到任何四方性。对113和400衍射的半高宽度随温度的变化进行了监测，发现了它们的可逆变化。结果表明，在室温下，两种衍射的半高宽度由于其四方分裂而变宽，而在温度高于Tc时，半高宽度变小。喇曼光谱随温度变化的系统测量支持了钛酸钡热液粉末的四边形。我们在样品上检测了立方钛酸钡在150℃时的抑制光谱。也就是说，抑制光谱不能用于识别晶体的点群。然而，我们监测了在转变温度下抑制光谱强度的急剧可逆变化，得出了样品在室温下为四方钛酸钡的结论。少

The following commercially available barium titanate powders were investigated with the intentions t find the size of the smallest tetragonal particle. Those were hydrothermal barium titanate made by Sakai Chemical Industry Co., Ltd ; BT-01 and BT-006 with respective nominal sizes of 100 nm and 6 nm, respectively. Another powder of KCM Corp., was made by a solid state reaction with a nominal size of 700 nm.The latter powder was CIPed under 1GPa repeatedly at room temperature to characterize by powder X-ray diffraction, TEM and heat capacity measurements. The tet-cub transformation enthalpy of the CIPed once powder was 1/15 of that of the normal. However, it was tetragonal after CIPed for 60 times although the crystallite size was decreased to 47 nm. Further, tweedy and /or squeezed texture was revealed by TEM to comprise collapsed boundary zones and modulated lattice arrays.Some papers have reported about cubic barium titanate of BT-01. However, this research made it clear that all the … More powders were tetragonal for as received BT-01 ad BT-006, and their heated specimens. This conclusion was derived from following results, however, even very careful electron diffraction examinations failed to detect any tetragonalty on as received powder of BT-01. The half height widths of 113 and 400 diffractions were monitored as functions of temperature to find their reversible changes. These results said that the half height widths of the two diffractions were wide at room temperature because of their tetragonal splittings, and those became smaller at higher temperature that Tc.Systematic measurements of Raman spectrum as functions of temperature supported the tetragonal barium titanate of hydrothermal powders. We had detected on specimens the inhibited spectra for cubic barium titanate at 150℃. That is the inhibited spectra are no use to identify the point group of the crystals. However, we had monitored the sharp reversible changes in intensities of inhibited spectra at transformation temperatures to conclude the specimens were tetragonal barium titanate at a room temperature. Less