EPR of NEW phosphorus-containing CENTERS in synthetic diamonds
V. A. Nadolinnyi1, A. Yu. Komarovskikh1, Yu. N. Pal’yanov2, I. N. Kupriyanov2
1A. V. Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences
2V. S. Sobolev Institute of Geology and Mineralogy, Siberian Division, Russian Academy of Sciences
Keywords: phosphorus, nitrogen, vacancy, synthetic diamond, BARS technology, electron paramagnetic resonance
Abstract
The effect is studied of electron and X-ray irradiation on phosphorous centers in synthetic diamonds grown in the P–C medium by the Bars technology. After exposure to X-ray irradiation, a new paramagnetic phosphorus-containing center NP6, in addition to the phosphorous centers NP4 and NP5, is observed in diamonds annealed at a temperature of 2300°С and pressure of 7.5 GPa. The spectrum of NP6 is simulated to give the following parameters: A1 = 29.42 G, A2 = 23.28 G, A3 = 75.85 G, g1 = 2.00085, g2 = 2.00083, and g3 = 2.00083. The NP4–NP6 centers are assumed to be genetically related to the three nitrogen–phosphorous centers NP1–NP3 and be formed as a result of the transformation of the tetrahedral environment around the phosphorous atom into an octahedral environment at an annealing temperature of 2300°C. The synthetic diamonds annealed at 2300°С were successively exposed to irradiation with electrons with energies of 3.5 MeV (5×1017 e/cm2) and annealing at temperatures of 500°C and 700°С. The EPR method is used to find that annealing of the electron-irradiated crystals at 700°С leads to the formation of a new paramagnetic center with spin S = 1 and hyperfine structure (HFS) from one phosphorus atom with the parameters: g = 2.0012, D = 19.7 G, and А(Р) = 3.6 G. The center is likely to have an eight-vacancy chain structure with a phosphorus atom located at the center.
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