Effects of chemical compositions and temperatures on the distortion phenomena observed in perovskite-type structures.

化学成分和温度对钙钛矿型结构中观察到的变形现象的影响。

基本信息

批准号：
10490009
负责人：
HORIUCHI Hiroyuki
金额：
$ 6.46万
依托单位：
Hirosaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

The relationship between chemical compositions and crystal structures were investigated through the materials surveying of perovskite-type phases. The behaviors of structural changes due to chemical compositions and temperatures were studied mainly on the double-oxide perovskite phases. On the other hand, phase stability conditions of boride perovskite phases were considered based on the boron contents as well as their physical properties such as hardness. Syntheses were performed by solid-solid reaction for double-oxides, and flux and arcmelting methods were used for the syntheses of boride perovskite phases. Crystallographic characterizations were mainly carried out by powder X-ray diffraction using shield tube source, and synchrotron radiation were applied in case of the necessity of high-resolution analyses for peak separations. The results of this research project were briefly summarized as follows :1. Double-oxide perovskite phases : Combination of trivalent rare-earth elements a … More nd Al^<3+>, that of divalent alkali-earth and tetravalent rare-earth elements as well as Zr^<4+>, were considered, and structures and structural changes of their end-member and solid solution phases were investigated. As a result, the phases of BaCeO_3, and BaPrO_3, belong to orthorhombic structures and BaZrO_3 is cubic as reported in literatures. However, BaTbO_3 is concluded to be an orthorhombic structure against the past report to be trigonal (rhombohedral lattice). Furthermore, we found that solid solutions of Ba(Pr_<1-x>, Zr_x)O_3 and Ba(Tb_<1-x>, Zr_x)O_3 show the changes from orthorhombic to cubic structures through trigonal lattice in the compositional range of x=0〜1, and that BaPrO_3 shows a similar structure change by temperature increase. These phenomena should be compared with similar structural change which takes place in the solid solution of (Sm_<1-x>, Nd_x) AlO3 by changing x and/or temperatures. Thus, the perovskite-type structures are controllable by an appropriate selection of A and B ions and a temperature condition.2. Boride perovskite : The relationship between chemical composition and structure stability of RB_<1-x>X_3 (R : Rare- earth, X : Noble metal) were mainly investigated based on the syntheses and crystallographic characterizations. The physical properties such as hardness and anti-oxidation properties were considered as well. New materials with interesting structural and physical properties are prospected by conjunction with extensive surveying of various phases, their stoichiometry and structures. Less

通过对钙钛矿型相的材料研究，研究了化学成分和晶体结构之间的关系，主要研究了双氧化物钙钛矿相的化学成分和温度引起的结构变化行为。根据硼含量及其物理性质（例如硬度）来考虑硼化物钙钛矿相的合成，通过双氧化物的固-固反应进行合成，并使用助熔剂和电弧熔炼方法来合成。硼化物钙钛矿相的晶体学表征主要通过使用屏蔽管源的粉末 X 射线衍射进行，并在需要高分辨率分析峰分离的情况下应用同步辐射。如下：1. 双氧化物钙钛矿相：三价稀土元素和 Al^<3+> 的组合，二价碱土元素和四价稀土元素的组合考虑了Zr^<4+>元素，研究了它们的端元相和固溶体相的结构和结构变化，结果表明BaCeO_3和BaPrO_3属于斜方结构，BaZrO_3为斜方晶系。然而，BaTbO_3 被认为是斜方晶系结构，而过去的报道则为三角晶系（菱面体结构）。此外，我们发现Ba(Pr_<1-x>,Zr_x)O_3和Ba(Tb_<1-x>,Zr_x)O_3的固溶体在组成上表现出通过三角晶格从正交结构到立方结构的变化。 x=0〜1的范围内，BaPrO_3随着温度的升高表现出类似的结构变化，这些现象应该与固体中发生的类似结构变化进行比较。通过改变x和/或温度来制备(Sm_<1-x>,Nd_x)AlO3。因此，钙钛矿型结构可以通过适当选择A和B离子以及温度条件来控制。2．主要基于合成和晶体学表征研究了RB_<1-x>X_3（R：稀土，X：贵金属）的化学成分与结构稳定性之间的关系。通过对各种相、化学计量和结构的广泛研究，还考虑了诸如硬度和抗氧化性能的新材料。