Effect of A-site deficiency on investigation of structural, magnetic and magnetocaloric behaviors for (LaSr)-lacunar manganites

We investigated the effect of both lanthanum and strontium deficiencies upon the structural, magnetic and magnetocaloric properties in La0.7Sr0.3MnO3 mixed-valence manganite. Lacunar powder oxides La-0.7 x square x Sr0.3MnO3 and La-0.7 x square x Sr0.3MnO3 (x= 0, 0.01, 0.02 and 0.05), where square is a vacancy, were prepared by the sol-gel technique by sintering at 750 degrees C and 850 degrees C. Our synthetized samples crystallize in a rhomboedrically distorted perovskite structure with space group R-3C. Both these series of samples are ferromagnets and undergo second order paramagnetic-ferromagnetic transition with decreasing temperature. Magnetization measurements versus magnetic applied field at low temperature confirm the ferromagnetic behavior of our lacunars samples. Curie temperature decrease with increasing vacancy content for strontitum-deficient samples, while, its shows a maximum at about x = 0.01 (T-c = 358 K) followed by a minimum for x = 0.03 (T-c = 336 K) for lanthanum- deficient compounds. All compounds undergo a large magnetocaloric effect and have consequently potential applications in magnetic refrigeration domain around room temperature. (C) 2018 Elsevier B.V. All rights reserved.