Hyperfine properties of La(V_1−xFe_x)O₃ compounds

LaV_1−xFe_xO₃ perovskites were synthesized in the vanadium-rich concentration range (i.e., x < 0.5) and characterized structurally and for the hyperfine properties of the iron nuclear probe. The aim of this investigation was to better understand the physical transformations that take place in the undoped compound (LaVO₃) at low temperatures. For that, X-ray diffraction analysis and, more extensively, ⁵⁷Fe Mössbauer spectroscopy were applied. The results revealed that the LaV₁-xFexO₃ vanadium-rich perovskites are orthorhombic at RT, and their lattice parameters decrease with increasing vanadium concentration. Lowering the temperature, the system becomes magnetic, with the iron moment freezing progressively. The presence of two magnetic subspectral components obtained at the lowest measurement temperatures suggests that the vanadium-rich samples, including LaVO₃, undergo a phase transition from an orthorhombic to a monoclinic structure at low temperatures.