X‐ray topographic investigation of growth defects in natural calcium fluoride crystals

Abstract

AbstractCalcium fluoride crystals have been cleaved along {111} faces and the freshly cleaved faces have been chemically etched in 2.6 N nitric acid solution. The etched faces have been optically studied. One‐to‐one correspondence of dislocation etch pits have been established on the matched cleavage faces and on the opposite sides of thin flakes. The same crystal has been studied using X‐ray topographic technique. By using 022‐ and 022 reflections, stereopair projection topographs were studied and compared with the optical micrographs. The close resemblance between dislocation etch pits and dislocation out‐crop images has been established. The orientation of the Burgers vectors of the dislocation lines has been identified using AgKα radiation with 111‐, 111‐ and 111 reflections. It has been confirmed that Burgers vectors of dislocation lines lie parallel to 〈110〉 directions. The implications are discussed.