Influence on Thermal Stability of lib Type Diamond Single Crystals under High Temperature Annealing

The synthesizing experiments ofⅡb type diamond single crystals were carded out at six-anvil high-pressure apparatus with iron-based catalysts doped with hBN made by powder metallurgy method.The diamond crystals were annealed in inert gases for 60min at 600℃,800℃and 1100℃respectively.DTA and TG analysis were carried through on the diamonds before and after annealing by a thermal analysis system.And their thermal stability was compared in atmosphere at the same time.The results indicate that the thermal stability of theⅡb type diamonds is improved obviously by annealing process,however,while anneal temperature is getting higher and higher,the thermal stability ofⅡb type diamond single crystals appeares downtrend,so there is an optimum temperature annealed for the crystals.