Study On The Color Of Diamond Treated By High Temperature And High Pressure Annealing And Electron Irradiation

For diamond gets excellent physical and chemical properties,it has been widely used in many aspects of industry production and normal life.In recent years,with the improvement in high temperature and high pressure synthetic diamond research and manufacturing,it already extent alleviated the urgent needs of the industrial production of diamond products,some diamonds with high quality even already put on the market to further facilitate the social consumer demand for diamond.However,there are still a considerable amount of the diamond products can not be utilized well for their minor inner or apparent defects.It is a great waste of resources and economic losses.Therefore,it is very essential to use scientific and safe methods to deal with certain synthetic diamond.Which will not only effectively improve resource utilization rate,further reducing manufacturing cost,but also greatly promote the development and comprehensive competitiveness of diamond enterprises in China.This paper take the hinged cubic press as the experiment instrument,try to do the study on the color of synthetic diamond treated by high temperature and high pressure annealing by exploring the optimal selection of pressure medium and the reasonable adjustment of the assembly structure of the core chamber in 5-7GPa,1500 to 2000 ℃.Meanwhile,the study use common industrial irradiation source to do the type IIa diamond irradiation,and try to find out the color difference before and after the experiment.Our study has found:First,in the same assembly structure,the temperature and pressure range when take the special substance X as the medium is larger than the choice of graphite,Moreover,the stability which take this substance as the medium is better than which take graphite as the medium under the same temperature and pressure condition.Second,the color change process of the type I b diamond during the high temperature and high pressure annealing treatment is quite complex.In the early period,the content of graphite or amorphous carbon decrease sharply due to the homogeneous multiphase transformation,which make the related dark tone fade seriously.But for the original isolated nitrogen atoms absorbed on the graphite or amorphous carbon still in their formal place,which makes the diamond occurs a uneven dark brown color.After that,with the deeper migration and aggregation of the isolated nitrogen,the initial diamond can turn to even lightcolor,until to a near colorless type Ia diamond.Third,the green fluorescence captured by DiamondView was probably due to the isolated nitrogen atoms absorbed on the graphite or amorphous carbon in the diamond crystals.Fourth,it is not wisely by to increase the annealing temperature and pressure unlimited,because when temperature and pressure exceeds the diamond synthesis temperature,it becomes much easier to cause digitization of diamond surface.At the same time,high temperature and high pressure will be a threat to operation of high temperature and high pressure equipment and normal experiment and production.Firth,it was found that after the electron irradiation by the use of dynamitron accelerator,the initial colorless type IIa diamond crystal would add a pink color,and there were some burning traces on the surface of the diamond,which was caused by the oxidizing reaction under High temperature condition during the irradiation.The color of fluorescence captured by DiamondView was changed from light blue to golden yellow.The highlight of this study is successfully explains the complex color change experienced by the type Ib diamond with black color treated by HPHT annealing.After long time repetition,the result of this research was turned effective,especially the one to make the dark appearance diamond colorless and the one to make colorless sample a pink color after specific treatment,both of them were thought to be a promising technology in the production and market promotion.