Graphitization of Diamond

Abstract

IN an earlier article in Nature ¹ I reported some results of a study of the high-temperature transformation of diamond to graphite. In this work diamond powder of 0–1μ particle size was used. Samples which had been heated in vacuum to various temperatures in the range 1,000–2,000° C. were obtained and these were investigated by microscopy and diffraction in a Siemens electron microscope (Elmiskop I). Specimens which had not been heated above about 1,200° C. gave diamond diffraction patterns only, those which had been heated to 2,000° C. gave graphite patterns only, and those which had been heated to about 1,600° C. gave both diamond and graphite patterns and also some extra spots not due to either diamond or graphite. It was suggested that these extra spots were due to some intermediate arrangement of carbon atoms, possibly a regular array of diamond-like and graphite-like regions produced during the graphitization. More recent work has shown that this interpretation of the results is not justified, and it is the purpose of the present communication to describe the diffraction patterns in more detail and to give such interpretation of them as at present seems reasonable.