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=358K) followed by a minimum for x=0.03 (T_C=336K) for lanthanum- deficient compounds. All compounds undergo a large magnetocaloric effect and have consequently potential applications in magnetic refrigeration domain around room temperature.

我们研究了镧和锶的缺乏对La _0.7 Sr _0.3 MnO ₃混合价锰矿的结构，磁性和磁热性能的影响。腔隙性粉末氧化物La _0.7-x □ _x Sr _0.3 MnO ₃和La _0.7 Sr _0.3-x □ _x MnO ₃（x = 0，0.01，0.02和0.05），其中□为空位，是通过溶胶-凝胶技术通过在750°C和850°C的温度下烧结而制备的。我们合成的样品在带有R-3C空间群的菱形扭曲的钙钛矿结构中结晶。这两个系列的样本都是铁磁体，并且随着温度的降低而经历二阶顺磁-铁磁跃迁。低温下的磁化强度与磁场的关系证实了我们腔隙样品的铁磁行为。对于缺乏晶状体的样品，居里温度随着空位含量的增加而降低，而居里温度在x = 0.01（T _C = 358K）时显示最大值，随后在x = 0.03（T _C）时显示最小值。= 336K），用于缺乏镧的化合物。所有化合物都具有很大的磁热效应，因此在室温附近的磁制冷领域具有潜在的应用前景。