Low-Symmetry Aspects in EPR Spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ Sites in BiVO$\text{}_{4}$ Single Crystal

Zero-field splitting parameters obtained from EPR X-band experiments of Baran et al. (1985) and Yeom et al. (1992) are reanalyzed. Transformation relations are derived to express the two sets of data in the same axis system. Problems arising from using a truncated zero-field splitting Hamiltonian in fitting the experimental data are elucidated. Low-symmetry aspects in EPR spectra of Mn$\text{}^{2+}$ at Bi$\text{}^{3+}$ sites in BiVO$\text{}_{4}$ single crystal are considered. Good agreement for orthorhombic parameters b$\text{}_{2}^{0}$ and b$\text{}_{2}^{2}$ is obtained indicating that the centres observed in the two cases are the same Mn centres. The remaining b$\text{}_{k}^{q}$ parameters accounting for the actual site symmetry around Mn$\text{}^{2+}$ impurity which seems to be lower than orthorhombic in the ferroelastic phase cannot be unambiguously determined from the existing EPR data.