EPR ofMn+2in Calcium Fluorophosphate. I. The Ca(II) Site

There are two different calcium sites in calcium fluorophosphate, called Ca(I) and Ca(II). Manganese ions have been found at the Ca(I) site by several investigators using EPR techniques. We report the observation of manganese at the Ca(II) site. The EPR spectrum of these ions, i.e., of Mn(II), has been fit with a spin Hamiltonian which includes crystalline $D$ and $E$ terms, an isotropic hyperfine term, and an axial superhyperfine term expressing its coupling to a nearby fluorine ion. The symmetry properties of the spectrum and the superhyperfine coupling to fluorine are the basis for the identification with Mn(II). The dependence of the concentrations of Mn(I) and Mn(II) upon the manganese concentration in the melt has been measured and is consistent with current speculations about the substitution of manganese into calcium fluorophosphate.