EPR study of Si‐ and Ge‐related defects in HPHT diamonds synthesized from Mg‐based solvent‐catalysts

Abstract

In this work, high pressure high temperature (HPHT) diamonds synthesized in the Mg–C system with germanium, silicon and boron additives were studied. In the photoluminescence spectra of the samples doped with Ge, an intense system 602 nm attributed to germanium‐vacancy defects was detected. In the electron paramagnetic resonance (EPR) spectra of these samples, a new paramagnetic center with S = 1 was detected along with substitutional nitrogen P1 and silicon‐vacancy KUL1 (SiV0) centers. The angular dependence investigation of the new spectrum allowed us to establish its spin Hamiltonian parameters: g|| = 2.0025, g⊥ = 2.0027, D = 80.3 mT, E = 0. The center was determined to have the symmetry axis parallel to 〈111〉. Hyperfine structure (HFS) of one 73Ge atom (I = 9/2) was observed for the new spectrum. The novel paramagnetic center was proposed to be the neutral germanium split‐vacancy defect. EPR and luminescence studies of diamonds doped with Si and B revealed a new paramagnetic center that can be associated with the sharp luminescence system 720 nm. An analysis of the angular dependence of the EPR spectrum showed that it had electronic spin S = 1/2 and anisotropic g‐factor: g1 = 2.0033, g2 = 2.0004, and g3 = 2.0024. Based on the principal values and directions of the g‐tensor the detected center was suggested to have the structure of silicon and boron atoms in the nearest carbon positions.