M\"{o}ssbauer spectroscopy investigation of lithium oxide-hematite solid solution

Lithium oxide-doped hematite $x$Li$_{2}$O $_{\ast}$ (1-$x)$ $\alpha $-Fe$_{2}$O$_{3}(x=$ 0.1-0.7) solid solutions were prepared via ball milling. Samples were taken at 0, 2, 4, 8, and 12 hours ball milling time (BMT). Parameters for the obtained M\"{o}ssbauer spectra were determined by least-squares fitting using NORMOS-90 software. For all initial Li$_{2}$O concentrations, partial substitution of Fe$^{3+}$ in the Li$_{2}$O lattice and vice versa was seen beginning at two hours BMT. For $x=$ 0.1, 0.3, and 0.5, spectra were fit with one or two sextets and one quadrupole-split doublet. For $x=$ 0.7, all spectra were fit with a single sextet and one quadrupole-split doublet. With increased BMT, the abundance of the doublet increased, irrespective of initial Li$_{2}$O concentration. For example, the abundance of the doublet increased from 2.3{\%} at 2 h BMT to 11.1{\%} at 12 h BMT for $x=$ 0.1. The increasing abundance of the doublet indicates greater substitution of Li$^{+}$ by Fe$^{3+}$ in the Li$_{2}$O lattice. Increasing the initial concentration of Li$_{2}$O for constant BMT did not consistently increase the abundance of the doublet. The results of this experiment demonstrate the feasibility of forming solid solutions by purely mechanical methods, e.g. ball milling.