Structure control in atomic scale of relaxors with morphotropic phase boundary composition

（1）Pb（Sc_（1/2）Nb_（1/2））O_3/PbTiO_3超晶格薄膜的制备及介电性能采用脉冲激光沉积（PLD）技术在单台阶SrTiO_3（001）衬底上制备了高取向Pb（Sc_（1/2）Nb_（1/2））O_3（PSN）和PbTiO_3（PT）超晶格薄膜。SrRuO_3沉积在衬底上作为介电测量的底电极层。用X射线衍射（XRD）方法对薄膜的取向和结构进行了分析。通过XRD观察到清晰的超晶格反射，并由超晶格的XRD剖面计算出超晶格的周期、相关长度和镶嵌度。介电常数的真实的部分在室温下在102 ~ 105 Hz的频率范围内约为350。（2）在过渡金属氧化物薄膜中观察到的电场感生电阻开关我们发现，在各种过渡金属氧化物薄膜中，电场引起的非易失性电阻开关几乎以相同的方式发生。这一结果表明，与普遍接受的相反，钙钛矿锰氧化物绝不是这种现象的特殊化合物。还建议电阻切换不受每个样品的详细电子结构支配，而是受更一般的起源支配，例如，晶体缺陷

(1)Syntheses of super lattice thin films of Pb(Sc1/2Nb1/2)O3/PbTiO3 and dielectric propertiesHighly oriented Pb(Sc_<1/2>Nb_<1/2>)O_3 (PSN) and PbTiO_3 (PT) super-lattice thin films are synthesized on single-stepped SrTiO_3 (001) substrates by pulsed laser deposition (PLD) technique. SrRuO_3 is deposited on the substrate as a bottom electrode layer for dielectric measurements. The orientation and structure of the films are checked by X-ray diffraction (XRD) method. Clear super-lattice reflections are observed by XRD and the period of super-lattice, the correlation length and the mosaicity are calculated from XRD profiles of the super-lattice. Real part of the dielectric constant is about 350 at room temperature in the frequency range of 102〜105 Hz.(2)Electric-field-induced resistance switching observed in transition-metal-oxide thin filmsWe show that polarity-dependent, nonvolatile resistance switching by electric field occurs in the thin film of various transition-metal oxides in almost the same manner. This result indicates that contrary to the general acceptance, perovskite manganite is by no means a special compound for this phenomenon. It is also suggested that the resistance switching is not dominated by a detailed electronic structure of each sample, but dominated by a more general origin, e.g., crystalline defect.