Electron paramagnetic resonance spectroscopic study of carbonate-bearing fluorapatite: New defect centers and constraints on the incorporation of carbonate ions in apatites

摘要

X-band electron paramagnetic resonance (EPR) spectra of gamma-irradiated crystals of carbonate-bearing fluorapatite from the Levant mine, Cornwall, England, revealed the presence of two previously characterized centers (i.e., an O– defect and an O–_F defect, where _F represents a vacancy at the F site), a CO₂– radical, and a new oxygen-associated hole-like center in the anion column. The O–_F center in carbonate-bearing fluorapatite is stable at room temperature, whereas in carbonate-free fluorapatite the stability of this radical is shifted to lower temperatures ( F–F–F–+ Ca2+ + PO₄3–.