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

Highlights: • The samples crystallize in the rhombohedral structure with R-3C space group. • T_C shows a maximum at x = 0.01 followed by a minimum at x = 0.03 for La-lacunar oxides. • T_C decrease with increasing vacancy content for strontium-deficient samples. • (1/χ) versus temperature indicates Griffiths phase occurrence. • Result show that the paramagnetic-ferromagnetic transition is of second order. We investigated the effect of both lanthanum and strontium deficiencies upon the structural, magnetic and magnetocaloric properties in La_0.7Sr_0.3MnO₃ mixed-valence manganite. Lacunar powder oxides La_0.7−x□_x Sr_0.3MnO₃ and La_0.7Sr_0.3−x□_xMnO₃ (x = 0, 0.01, 0.02 and 0.05), where □ is a vacancy, were prepared by the sol–gel technique by sintering at 750 °C and 850 °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.