NICKEL-ASSISTED METASTABLE DIAMOND FORMATION (SURFACE RECRYSTALLIZATION) IN A DISSOLUTION MEDIUM AT ATMOSPHERIC-PRESSURE

Surface recrystallization of diamond has been found to occur at atmospheric pressure in a diamond dissolution medium containing nickel. The experimental procedure consisted of an initial dissolution of selected diamond crystal chips together with nickel in NaOH at a temperature around 1100 K followed by quenching the system to room temperature. Subsequent surface micromorphological examination of the chips revealed growth features which were identified and characterized as diamond growth after a detailed study by various techniques. Evidence for the role of nickel in the process was obtained, apparently similar to that in the case of high pressure diamond growth from solution: the occurrence of catalyst film covering the newly formed (recrystallized) diamond. Detailed surface microstructural examination gave evidence suggesting two distinct growth mechanisms to be possible. While the metastable growth of diamond from the vapour phase is now being accepted as a major technological achievement with far reaching consequences involving the exploitation of the unique properties of such films, a better route to larger diamond crystal growth is thought to be through low pressure growth from solutions.