Paramagnetic resonance of trivalent iron in single-crystal potassium tetrafluoaluminate

Single-crystal potassium tetrafluoaluminate-doped substitutionally with iron has been prepared. The room-temperature spectrum of isolated iron ions may be described by a conventional spin Hamiltonian with parameters: g∥=2.005, g⊥=1.999, D=0.1471 cm-1, a=0.0020 cm-1, and F=0.007 cm-1. From the linewidths an upper limit to the fluorine hyperfine structure is estimated. © 1967 The American Institute of Physics.