Polaronic Conductions in Transition Metal Oxides and its Application for Condensers.

在大多数过渡金属氧化物中，大多数载流子是极化子。极化子是定域在离子上的电子(或空穴)和电子-声子相互作用引起的电子周围晶格形变的结合。极化子在具有晶格形变的离子之间的跳跃过程导致这种氧化物中的电导。因此，由于晶格形变，极化子的有效质量与半导体中的传导电子和金属中的传导电子相比非常大，因此可以预期极化子的漂移迁移率很低。另一方面，带电荷的极化子运动会产生偶极矩，介电常数预计会很高。极化子的这些特性导致了一种以极化子为主要载流子的氧化物可能是电容器的候选者之一。本项目就是基于这一策略进行的。本项目包括测量Diele…的实验更多的介电性质和直流电导，以及利用Anderson的极化子吸引势和壳模型进行的理论计算。进行了La_2O_3和MnO_2掺杂的Li_xNi_&lt；1-x&gt；O，Li_xCo_t；1-x&gt；O，α-Li_xMn_2O_3，SrMnO_3，3-x&gt；和SrTiO_3。Li_xNi_(lt；1-x&gt；O)、Li_xCo_(1-x&gt；O)和α-Li_xMn_2O_3的实验结果显示了极化子跳跃过程的典型行为，并给出了一些与极化子有关的重要参数。这些参数在极化子的理论研究中是必不可少的。此外，对Li_xNi_(1-x)&Gt；O的理论计算还证明了极化子在氧化物中是稳定的，并给出了电子-声子相互作用的强度和局域电子周围离子的位移量。除α-Li_xMn_2O_3外，其他氧化物具有较高的介电常数和较低的电导率，但在室温下不是绝缘体。然而，已经在技术上建立起来的陶瓷边界层绝缘方法必须解决这一难题。掺杂La_2O_3和MnO_2的SrMnO_3、3-x&gt_3和SrTiO_3并没有表现出极化子导电性，但这些氧化物的实验为介电材料的理论研究提供了非常有用和重要的知识。较少

In most transition metal oxides, majority carriers are polarons. A polaron is the combination of an electron (or a hole) localized at an ion and the lattice deformation around the electron induced by electron-phonon interactions.The hopping process of polarons between ions with lattice deformations gives rise to conductivities in such oxides. The effective mass of polarons are, therefore, very large in comparison with conduction electrons in semiconductors like Si, Ge and so on and metals because of lattice deformations and, consequently, one can expect very low drift mobilities of polarons. On the other hand, a motion of a polaron with an electronic charge results in a dipolemoment and the dielectric constant is expected to be very high. These characteristics of polarons lead to a possibility that an oxide which has polarons as majority carriers is one of candidates for condensers. The present project is based upon this strategy.This project consists of the experiments measuring diele … More ctric properties and dc-conductivities and theoretical calculations using Anderson's attractive potential for polarons and a shell model. Experiments on Li_xNi_<1-x>O, Li_xCo_<1-x>O, alpha-Li_xMn_2O_3, SrMnO_<3-x> and SrTiO_3 doped with La_2O_3 and MnO_2 are carried out. The experimental results of Li_xNi_<1-x>O, Li_xCo_<1-x>O and alpha-Li_xMn_2O_3 show typical behaviors due to hopping process of polarons and yield several important parameters relevant to polarons which have been unknown. These parameters are indispensable in theoretical investigations of polarons. Theoretical calculation on Li_xNi_<1-x>O, in addition, proves that polarons can be stable in oxides, and also yield the strength of electron-phonon interaction and magnitudes of displacements of ions around the localized electron. These oxides except alpha-Li_xMn_2O_3 have high dielectric constants and low conductivities as expected, but are not insulators at room temperature. However, the method to insulate boundary layrs in ceramics, which has been technically established, must resolve this difficulty. SrMnO_<3-x> and SrTiO_3 doped with La_2O_3 and MnO_2 do not show polaronic conductions but very useful and important knowledges on theoretical studies of dielectrics are available from the experiments on these oxides. Less