HIGH PRESSURE HIGH TEMPERATURE MATERIALS PROCESSING

The purpose of the research proposal is to enable the Warwick Diamond Research Group to take advantage of a unique opportunity to acquire a High Temperature High Pressure Tetrahedral Diamond Press (HTHP Press) for extreme high-temperature materials processing under stabilising pressures. This HPHT Tetrahedral Diamond Press can access temperatures up to 3000 deg C and hydrostatic pressures up to 20 GPa (equivalent to 2 million atmospheres), which is equivalent to a depth of >600 km. The HPHT Press was constructed by Element Six Ltd for an in-house research project at the Diamond Trading Company research Centre, Maidenhead, who now no longer routinely utilise its capabilities and are willing donate it to the University of Warwick as part of their continued support for University research. The HPHT Press would provide a world leading, state of the art capability in the UK, enabling new science and innovative research programmes. The initial focus of the feasibility studies will be on HPHT diamond processing, however the potential of the HPHT Tetrahedral Diamond Press to impact significantly on the research of other materials will not be overlooked. The data obtained in the feasibility studies will enable informed and focused full research proposals, utilising the extreme processing conditions, which will follow. Many of the important physical and technologically useful properties of materials are obtained by processing at elevated temperatures and are controlled by diffusion. The exceptional properties of diamond (e.g. electronic, optical, mechanical etc) and recent advances in synthesis provide the academic and technological motivation to study diffusion in diamond. Very high temperatures are required to initiate bulk diffusion in diamond, but at these temperatures diamond is not stable and will convert to graphite unless very large pressures are applied. This HPHT Press provides enabling technology that will allow investigation of self and impurity diffusion in diamond via monitoring concentration profiles with Secondary Ion Mass Spectroscopy, pre and post HPHT annealing. Samples with interfaces where the carbon isotope abundance (12C:13C) or the impurity (e.g. nitrogen, boron, hydrogen etc) concentration changes abruptly are available for these feasibility studies. In addition to diffusion experiments, HPHT annealing studies will be performed to investigate the feasibility of dopant activation, the removal of defects which degrade the electronic/optical properties and the kinetics of defect complex formation/dissociation at very high temperatures.UK research groups have a reputation for world leading diamond research. This project strives to establish a new UK research effort by accessing the extreme processing conditions which should lead to breakthroughs in diamond science and facilitate new technological applications of diamond.