Structure, magnetic and magnetiocaloric properties in La1.4Sr1.6−xCaxMn2O7 perovskite compounds

Abstract The nominal compositions of La 1.4 Sr 1.6− x Ca x Mn 2 O 7 (0.0 ≤  x  ≤ 1.6) have been synthesized using solid-state reaction method. The XRD analyses show that the compounds are pure I 4/ mmm tetragonal bilayered perovskites phase for x  ≤ 0.8, while they are mixture of a main orthorhombic ABO 3 -type perovskite and a slight cubic calcium oxide for x  ≥ 1.0. For lightly doped samples ( x  ≤ 0.8), the 3D ferromagnetic (FM) transition temperature first declines and then disappears due to the depression of the interlayer exchange interaction by Ca 2+ doping. However, the intralayer exchange interaction is strengthened in the x  = 0.4 sample on account of large Jahn–Teller distortion of MnO 6 octahedra. A large magnetic entropy change of 2.28 J kg −1  K −1 is obtained in the nominal composition La 1.4 Sr 1.6− x Ca x Mn 2 O 7 ( x  = 1.6) upon 1 T applied magnetic field, which makes it suitable for sub-room temperature magnetic cooling material.