Magnetocaloric properties of Fe-substituted La-Sr-manganites

The effect of Fe doping on the structural, magnetic and magnetocaloric properties was studied on La1-xSrxMn1-yFeyO3 (x = 0.10, 0.20; y = 0.00, 0.10, 0.15) manganites prepared by solid state reaction method. X-ray structural analysis showed that the substitution of manganese by iron does not change the phase state in the rhombohedral series (x = 0.20). In the orthorhombic series (x = 0.1), the substitution of manganese by iron leads to a phase transition from the Jahn-Teller O' phase to the ordinary O & nbsp;phase. We explain this transition by a decrease in the concentration of Mn3+ ions, which are Jahn-Teller centers. In addition, we recorded an increase in the unit cell parameters in the iron-containing samples of both series. We explain this effect by the presence of a certain amount of Fe4+ ions. Magnetic measurements showed that all samples undergo a second order FM-PM transition at the Curie temperature (Tc). The Curie temperature T-C and the Curie-Weiss temperature (theta) decrease with increasing Fe content. The relationship between the variation of T-C and structural parameters the Me-O bond length and the bond angle of Me-O-Me with increasing Fe content has been established. In the paramagnetic temperature range, the formation of magnetic clusters was suggested from isothermal magnetization data. For a magnetic field variation of 5 T, the entropy change is evaluated.

Automated summary

The effect of Fe doping on the structural, magnetic and magnetocaloric properties of La1-xSrxMn1-yFeyO3 manganites has been studied. The substitution of manganese by iron leads to changes in crystal structure, phase state, and phase transitions. The Curie temperature and Curie-Weiss temperature decrease with increasing Fe content.