Photoand cathodoluminescence spectra of diamond single crystals formed by sintering of detonation nanodiamond

The photo- and cathodoluminescence spectra (PL, CL) of diamond single crystals synthesized under high-pressure and at high-temperature (HPHT sintering) from detonation nanodiamonds (DND) particles with Gd and Eu ion-functionalized surfaces have been studied. The HPHT sintering was made under pressures ($P \cong 7$ GPa) and temperature ($T = 1300$–$1500^\circ$ C). The DND particles have sizes of $4$–$5$ nm, hydrocarbons and/or alcohols were used at the HPHT synthesis instead of traditional metal catalysts. The initial and synthesized crystals were characterized by X-ray microanalysis, mass-spectroscopy, scanning electron microscopy (SEM), PL and CL. Mass spectra confirmed that Gd and Eu atoms were inserted into the volume of diamond single crystals in the HPHT sintering. A significant conversion of the PL and CL spectra of synthesized diamond single crystals compared with HPHT diamond crystals were observed. Transformation of the point defect assemblies inherent to the diamond crystal can explain the observed spectra.