Abstract
In this study we report the effect of lithium substitution on the structural, magnetic and magnetocaloric properties of La0.8K0.2-xLixMnO3 (0 ≤ x ≤ 0.075) samples synthesized by the sol–gel technique at low temperature. The investigated compounds crystallize in a rhombohedral system with R3¯c space group. The thermal variation of the magnetization under an applied magnetic field of 0.05 T showed that all our compounds exhibited a paramagnetic to ferromagnetic transition with decreasing temperature. With increasing lithium content, the Curie temperature TC, decreases from 287.4 K for x = 0 to 172.6 K for x = 0.075. The maximum of the magnetic entropy change, -ΔSMMax, is found to be 3.19, 3.51, 2.39 and 2.24 J kg−1 K−1 in a magnetic field change of 5 T for x = 0, 0.025, 0.05 and 0.075 respectively. The La0.8K0.175Li0.025MnO3 sample displays a higher maximum relative cooling power value of 320.5 J kg−1, equal to 78 % of that of gadolinium. Technically, this large value associated to a TC of 270 K makes the present sample very promising for magnetic refrigeration technology below room temperature.
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