Modeling EPR powder spectra of triclinic BiNb$_{1-x}$Mn$_x$O$_{4-\delta}$

EPR of solid solutions BiNb$_{1-x}$Mn$_x$O$_{4-\delta}$ in triclinic modification have been studied. The EPR spectra revealed sextet structure of Mn(II) ions with $8.4$ mT splitting and some features at $g=3.80$ and $1.47$, and a broad diffuse band with $g\approx2.2$ having a sextet with $8\div9$ mT splitting and $g=2.0$ against its background. The modeling has shown that the best reproduction of the components of the spectrum of triclinic BiNb$_{1-x}$Mn$_x$O$_{4-\delta}$ is observed with the following parameters: $g=2.0$, $D=1580\cdot10^{-4}$ cm$^{-1}$, $E=495\cdot10^{-4}$ cm$^{-1}$, $\Delta D/D=\Delta E/E=0.08$, $A=8.4$ mT, Lorentzian shape of the individual line with $\Delta B_{pp}=2.5$ мТ.