HREM STUDY OF OXYGEN-DEFECTIVE LAMNO3-X WITH TWIN STRUCTURE

Oxygen-defective LaMnO3-x with twin structure was studied using an HRE M. On the basis of direct observation with a 200-kV HREM and with the aid of computer simulation, an optimum imaging condition was found, wh ere metal La and Mn atoms and oxygen atoms were imaged as dark spots a nd bright spots, respectively, The through-focus observation and inten sity profile observed from the image contrast support the view that th e oxygen vacancies could be detected from the intensity distribution o f bright spots in the observed image, which represents the positions o f the oxygen atoms, A structure image under the optimum imaging condit ion reflected the twin structure with oxygen vacancies in LaMnO3-x. Tw in structures were found to consist of two kinds of twin planes, (110) and (112), including oxygen vacancies.