Copper-doped lanthanum manganite La <subscript>0.65</subscript> Ce <subscript>0.05</subscript> Sr <subscript>0.3</subscript> Mn <subscript>1- x </subscript> Cu <subscript> x </subscript> O <subscript>3</subscript> influence on structural, magnetic and magnetocaloric effects.

Bulk nanocrystalline samples of La 0.65 Ce 0.05 Sr 0.3 Mn 1- x Cu x O 3 (0 ≤ x ≤ 0.15) manganites are prepared by the sol-gel based Pechini method. The effect of the substitution for Mn with Cu upon the structural and magnetic properties has been investigated by means of X-ray diffraction (XRD), Raman spectroscopy and dc magnetization measurements. The structural parameters obtained using Rietveld refinement of XRD data showed perovskite structures with rhombohedral ( R 3̄ c ) symmetry without any detectable impurity phase. Raman spectra at room temperature reveal a gradual change in phonon modes with increasing copper concentration. The analysis of the crystallographic data suggested a strong correlation between structure and magnetism, for instance a relationship between a distortion of the MnO 6 octahedron and the reduction in the Curie temperature, T c . A paramagnetic to ferromagnetic phase transition at T C is observed. The experimental results confirm that Mn-site substitution with Cu destroys the Mn 3+ -O 2- -Mn 4+ bridges and weakens the double exchange (DE) interaction between Mn 3+ and Mn 4+ ions, which shows an obvious suppression of the FM interaction in the La 0.65 Ce 0.05 Sr 0.3 Mn 1- x Cu x O 3 matrix. The maximum magnetic entropy change -Δ S max M is found to decrease with increasing Cu content from 4.43 J kg -1 K -1 for x = 0 to 3.03 J kg -1 K -1 for x = 0.15 upon a 5 T applied field change.

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