Inversion boundaries developed by etching on{1010} of ZnO crystal

Etch pattern on surfaces of ZnO crystal has been observed by using an E.M. and an S.E.M. Two kinds of boundaries on which stacking orders of Zn and O atomic planes change have been developed on the plane {1010} by using etching technique. Hydrofluoric acid (～46%) was used as etchant. One boundary on which stacking of Zn and O planes changes from one order, -O.Zn-O.Zn-, to the other order, -Zn.O-Zn.O-, is a twin boundary. While, the other boundary on which stacking of Zn and O planes changes from the latter order to the former one is not considered as a twin one. Results of observation suggest to us that the decrease in the growth rate of the crystal needle is due to the generation of twin boundaries in the crystal

Simple method of obtaining replicas of selected and rather wide areas in electron microscopic study.

A simple method of obtaining replicas of selected areas of specimen surface is described. In the method, no specific apparatus other than an usual optical microscope is required as in Fourie\u27s method, in addition, handlings involved are very simple. The method is based on an usual two-stage filmy replica technique, and to observe rather wide area the slit type specimen carrier is employed. The correct positioning of the replica on the specimen carrier is done with ease in a short time. The advantages, disadvantages and applications of the method are also discussed