Nd-Ba-Cu-O高温超导体的高分辨电子显微术研究

HIGH RESOLUTION ELECTRON MICROSCOPY STUDY ON HIGH T_c SUPERCONDUCTOR Nd-Ba-Cu-O

用电子衍射和高分辨电子显微术研究了Nd-Ba-Cu-O高温超导体,主相属正交晶系,具有畸变钙钛矿亚结构的三倍超结构,晶胞参数为a=3.84,b=3.87,c=11.7,样品中存在大量的缺陷,用点阵象技术观察到刃位错,反向畴,并借助结构象确定了NdBa_2Cu_3O_(-)的结构模型。在不同成象条件下,高分辨电子显微象上或者重原子为白点,或者氧原子为白点,当成象条件适当时,可以在象上区分氧原子和氧空位。

Nd-Ba-Cu-O high Tc superconductor is studied with electron diffraction and high resolution electron microscopy. The main phase is orthrombic with distorted perovskite structure. The lattice parameters are a = 3.84A, b = 3.87A, c= 11.7A. There are many defects in the sample. Edge dislocations and anti-phase domains are observed by lattice imaging. The structure mode) of NdBa2Cu3O7-δ is determined from the structure image. Depending on the imaging conditions either the heavy atoms or oxygen atoms appear as white dots in the high resolution electron microscope images. The oxygen atoms can be distinguished from the vacancies in the image under a suitable imaging condition.