LAUSR

Abstract The influence of the A-site cation size-disorder σ 2 on the structural and magnetic properties of the polycrystalline Pr 0.4 Re 0.1 Sr 0.5−y Ba y MnO 3 (Re = Pr, Sm, Eu, Gd, Dy and Ho) samples with a constant average ionic radius A > = 1.2445 A, is investigated. All samples were synthesized using the solid-state reaction. Rietveld refinement of the X-ray diffraction patterns shows that the substitution generates a structural transition from tetragonal to orthorhombic symmetry. The temperature dependence of magnetization indicates a weakening of ferromagnetism by the increase of σ 2 . The large difference between the field cooled and zero field cooled magnetization below Curie temperature suggests the presence of an inhomogeneous mixture of a ferromagnetic and antiferromagnetic domains at low temperature. The maximum of the magnetic entropy change decreases with increasing the mismatch effect. However, several peculiarities were observed in the magnetic behavior indicating that σ 2 is not the only factor controlling the physical properties; the nature and the magnetic moment of the substituent should be taken in consideration.