Mössbauer spectra of ⁵⁷Fe in La_0.75M_0.25Cr_0.75Fe_0.25O₃ (M = Ca, Sr, Ba)

La_0.75M_0.25Cr_0.75Fe_0.25O₃ (M = Sr, Ba) compounds are synthesized by a wet chemical method, the crystal structure of the compounds belongs to the orthorhombic system. The Mössbauer spectra of ⁵⁷Fe reveal that all the iron ions in the compounds are trivalent and in high-spin state. There is a linear relationship between the quadrupole splitting of the ⁵⁷Fe nucleus and the electronegativity of the M ion in La_0.75M_0.25Cr_0.75Fe_0.25O₃ (M = Ca, Sr, Ba). Unlike in La_1-xSr_xFeO₃, the substitution of the divalent alkaline earth ion for the trivalent lanthanum ion does not lead to an increasing valence state of the Fe³⁺ ion in La_0.75M_0.25Cr_0.75Fe_0.25O₃ (M = Sr, Ba). Doping the alkaline earth ion will more likely lead to an increasing valence state of the Cr³⁺ ion.