In this work, diamond synthesized under high-pressure high-temperature (HPHT) conditions in the phosphorus-carbon system with addition of aluminum has been studied by electron paramagnetic resonance (EPR). It is established that microcrystals with different defect concentrations are formed. Nitrogen-phosphorus defects NP3 are observed in some microcrystals, although pure phosphorus paramagnetic centers NP8 and NP9 are detected in other microcrystals. The NP8 center has an electron spin S = 1/2, gxx = gyy = 2.0016, gzz = 2.0048, and hyperfine structure (HFS) of one phosphorus atom Axx = Ayy = 3.2 mT, Azz = 5.6 mT. The NP9 center has an electron spin S = 1/2, gxx = gyy = 2.0038, gzz = 2.0030, and HFS of two inequivalent phosphorus atoms A(P1)xx = A(P1)yy = 8.8 mT, A(P1)zz = 13.6 mT, A(P2)xx = A(P2)yy = 2.2 mT, A(P2)zz = 1.4 mT. The structures of the NP8 and NP9 centers are discussed. Concentration of phosphorus impurity in some microcrystals is high enough to detect conductivity electrons. Subsequent annealing of the samples at 2273 K leads to the disappearance of the NP3, NP8, and NP9 spectra; the NP4 spectrum is observed.
|Number of pages||4|
|Journal||Physica Status Solidi (A) Applications and Materials Science|
|Publication status||Published - 2015|
- electron paramagnetic resonance