Magnetic exchange interactions in perovskite solid solutions. Part 1. Iron-57 and 1 5 1Eu Mössbauer spectra of EuFe1 –xCoxO3(0 < x < 1)

Abstract

The ^{1 5 1}Eu and ⁵⁷Fe resonances have been used to study magnetic exchange interactions in the orthorhombic perovskite solid solution EuFe_{1 –x}Co_xO₃(O < x < 1). The replacement of a neighbouring Fe³⁺ ion by diamagnetic Co³⁺ ion results in a reduction in the flux density of the supertransferred hyperfine field at the ⁵⁷Fe nucleus of 1.02 ± 0.05 T extrapolated to 0 K. The ^{1 5 1}Eu resonance is considerably broadened by substitution; this effect is proved to be of magnetic origin, and a detailed model is proposed which explains the data quantitatively. The flux density of the molecular exchange field at the ^{1 5 1}Eu nucleus when a neighbouring Fe³⁺ atom is substituted by Co³⁺ is expressed by the exchange constant (β/k)B_o^m(0)= 3.2 ± 0.1 K.