HPHT Synthesis of Lithium and Nitrogen Codoped Single-Crystal Diamond and Formation of B Centers

In this research, lithium-doped and lithium–nitrogen codoped diamond single crystals were synthesized using a high-pressure high-temperature (HPHT) temperature gradient technique. Characterization of the impurities in diamonds was performed by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). According to the results from FTIR, XPS, and SIMS, lithium and nitrogen were simultaneously incorporated into the diamond lattice and bonded with carbon; the mutual influences between lithium and nitrogen impurities during the HPHT diamond growth were observed and analyzed. Annealing of the lithium–nitrogen codoped diamonds at 1600 °C and 3 GPa for a duration of 15 min resulted in the formation of B centers (N4 V), with lithium impurities supposed to play a…