Ion Dynamics in Superionic Conductors Studied by a Spectral Hole-Burning Effect

(1)研究了Eu^&lt；3+&gt；掺杂CeO_2-Y_2O_3和ZrO_2-Y_2O_3(YSZ)离子中^7F_0-^5 D_0跃迁的光学吸收和发光光谱。通过对位置选择性激发下的发光带的详细研究，得到以下结果。在Eu^&lt；3+&gt；/CeO^2-Y_2O_3中，发现了三种类型的三价离子中心：无空位、近邻位置有一个空位、次近位位置有一个空位。在YSZ中发现了无空位的三价离子中心和最近的Nieghbor空位上的1个和2个空位。(2)研究了不同成分的Eu^&lt；3+&Gt；掺杂的YSZ(ZrO_2-Y_2O_3)晶体的荧光线变窄(FLN)谱。在80K和300K之间，均匀的线宽与T^&lt；2.6&gt；成正比。由于均匀线宽和非均匀线宽具有不同的成分依赖关系，因此R(=Gamma_&lt；Inhomo&gt；/Gamma_&lt；Homo&gt；)在某些成分处有最大值。发现19mol%YSZ在20K时有一个极大值，R=5000。这一结果表明Eu^&lt；3+/YSZ体系可用于频域光存储。(3)在掺入2%Pr^&lt；3+&gt；的10mol%YSZ中，在6115A处发现了持续的烧孔效应。该空穴可在25K以下烧制，4.2K时其宽度为0.35 GHz。孔的宽度假定等于2GAMMA_lt；Homo&gt；，具有温度依赖性。这种温度依赖关系与嵌入在聚合物中的染料分子非常相似，并强烈地表明该体系的退相机制涉及稀土离子与TLS(二能级系统)的耦合。持续空穴可以作为一种新的工具来研究YSZ中可移动离子与缺陷中心的微观结构和相互作用。下一步，作为频域存储器的演示也将是一个富有成效的主题。

(1) The optical absorption and luminescence spectra of ^7F_0 -^5 D_0 transition in Eu^<3+> ions are studied for Eu^<3+> -doped CeO_2 -Y_2 O_3 and ZrO_2-Y_2O_3 (YSZ) systems. From a detailed study of the luminescence bands under site selective excitation, following results are obtained. In Eu^<3+> /CeO^2-Y_2O_3, three types of trivalent ion sites are found ; the site without vacancy, with one vacancy on the nearest neighbor site, and with one vacancy on the 2nd nearest site. In YSZ, trivalent ion site without vacancy and one and two vacancies on the nearest nieghbor site are found.(2) The FLN(fluorescence line narrowing) spectra are studied in Eu^<3+> -doped YSZ(ZrO_2-Y_2O_3) crystals with various compositions. The homogeneous line width is found to be proportional to T^<2.6> between 80K and 300K. Since the homogeneous and inhomogeneous line widths have different composition dependence, R(=GAMMA_<inhomo>/GAMMA_<homo>) has a maximum value at certain composition. It is found that the 19mol% YSZ has a maximum value, R=5000, at 20K. This result suggests usefulness of the Eu^<3+>/YSZ system for a frequency domain optical memory.(3) In 10mol%YSZ doped with 2%Pr^<3+>, we found a persistent hole-burning effect for ^3H_4-^1D_2 transition at 6115A. The hole can be burned below 25K and its width is 0.35GHz at 4.2K. The hole width, which is assumed to be equal to 2GAMMA_<homo>, has a T^<1.3> temperature dependence. This temperature dependence is very similar to that of the dye molecules embedded in polymers, and strongly suggests that the dephasing mechanism in this system involves a coupling of the rare-earth ions with TLS(two level system). The persistent hole can be used as a new tool to investigate the microscopic structures and the interaction of the mobile ions with the defect centers in YSZ. A demonstration as a frequency domain memory will be also a fruitful subject as a next step.