$^{13}$C and $^{11}$B NMR spectroscopy of high-pressure high-temperature boron-doped diamonds

Diamond micropowders with a boron content of 1 and 2.5% that have been synthesized under high pressure and high temperature conditions and studied. The method of nuclear magnetic resonance on $^{13}$C and $^{11}$B nuclei has been used for a comparative analysis of boron-doped diamond and boron-doped graphite. It has been shown that the structure of diamonds with a high boron content is disordered and contains a significant amount of carbon with trigonal coordination. The main signal in the $^{11}$B spectra of diamond microcrystals is due to the sum of contributions from single boron atoms with tetragonal and trigonal carbon environments. An additional signal in the spectra with a chemical shift of more than 60 ppm can be due to boron atoms in the areas of dislocation clusters, sub-boundaries, and other defective areas.