In-situ observation of the phase conditions of rare erath manganites controlled by structure and crystal structure and application of new properties

结构和晶体结构控制稀土锰矿物相条件的原位观察及新性能应用

基本信息

批准号：
18560662
负责人：
NAKANO Hiromi
金额：
$ 1.81万
依托单位：
Ryukoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

We synthesized new rare-earth manganites, and analyzed new crystal structures and new properties.1. Study of new rare earth manganites with K_2NiF_4 structureNew phase of BaLnMnO4 (Ln = Nd, La) was obtained by annealing the single crystal (I4/mmm) in a reducing atmosphere. The structural change was caused by an oxygen deficiency, and a small amount of Mn^<2+> ions was formed by annealing in a reducing atmosphere. Na-oxide has a crystal structure with Fmmm symmetry, and La-oxide has Cccm symmetry.2. Study of new oxides with perovskite related structuresMany new phases have been synthesized and investigated their structures, electrical properties, thermal properties and magnetic properties. In the case of (A^<0.67>Ln^<0.33>)(Mn^<0.33>Ti^<0.67>)O_3 (Ln=rare earth, A=Ca, Sr), the electrical conductivity was closely related with structural parameters (Mn-O angles, Mn-O distances, ionic radii, t-factors, and coulomb potentials).3. In-situ observations of phase conditions at elevated temperatureWe found a first-order phase transition in BaLn_2Mn_2O_7 with a layered perovskite structure using a high-temperature TEM and XRD. The structure change was caused by a distortion of structure and change in electrical structure. In-situ observation by a high-temperature TEM was effective in order to know the structural change at real time. On the other hand, secondary-order phase transition was observed in perovskites with ABO_3 structure. The phase transition was caused by tilting of octahedra BO_6.

我们合成了新的稀土锰，并分析了新的晶体结构和新特性。1。通过在还原的大气中退火，通过退火，可以获得Balnmno4（Ln = nd，la）的K_2NIF_4结构相（Ln = ND，LA）结构阶段的研究。结构变化是由氧缺乏引起的，少量的Mn^<2+>离子是通过在还原气氛中退火而形成的。 Na-氧化物具有带有FMMM对称性的晶体结构，LA-氧化物具有CCCM对称性。2。与钙钛矿相关结构的新氧化物的研究已合成并研究了它们的结构，电性能，热性质和磁性。在（a^<0.67> ln^<0.33>）（Mn^<0.33> ti^<0.67>）O_3（Ln =稀土，A = CA，SR）的情况下，电导率与结构参数（Mn-O Angles，Mn-O距离，Mn-O距离，Mn-O距离，Iromieniic Radii，Ionion Radii，Terfacts和coulb）密切相关。在升高温度下对相条件的原位观察，在Baln_2MN_2O_7中发现了使用高温TEM和XRD的层状钙钛矿结构的一阶相变。结构变化是由结构的失真和电结构变化引起的。高温TEM的原位观察是有效的，可以实时了解结构变化。另一方面，在具有ABO_3结构的钙钛矿中观察到次级相变。相转换是由Octahedra BO_6倾斜引起的。