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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Observation of enhanced magnetocaloric properties with A-site deficiency in La0.67Sr0.33MnO3 manganite
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Observation of enhanced magnetocaloric properties with A-site deficiency in La0.67Sr0.33MnO3 manganite

机译：La0.67SR0.33MNO3锰的现场缺乏增强磁热性能的观察

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摘要

In this paper, we have studied the effect on the structural, magnetic and magnetocaloric properties of La and Sr-deficiencies in the La0.67Sr0.33MnO3 compound. Rietveld refinement of the X-ray powder diffraction patterns confirms that all of the compounds have crystallized into a rhombohedral crystal symmetry with an R (3) over barc space group. X-ray photoelectron spectroscopy measurements revealed that the parent compound has a mixed valance of Mn3+/Mn4+, whereas Mn2+/Mn3+/Mn4+ mixed valency is found in the case of both La and Sr-deficient compounds. The La0.67Sr0.33MnO3 compound shows a magnetic transition temperature of 365 K, while the La and Sr-deficient compounds exhibit transition temperatures of 367 K and 355 K, respectively. Among the studied compounds, the Sr-deficient compound shows the highest magnetic entropy change (Delta S-M) of 5.08 J kg(-1) K-1 at 352 K for a 50 kOe field with a relative cooling power (RCP) of 142 J kg(-1) and an adiabatic temperature change of 3.48 K, while the parent and La-deficient compounds exhibit a -Delta S-M of 4.78 J kg(-1) K-1 at 364 K and of 4.12 J kg(-1) K-1 at 364 K, respectively. The temperature dependence of the electrical resistivity with and without applied magnetic fields reveals that the La-deficient compound has one order and the Sr-deficient compound has two orders of suppression in the electrical resistivity. Thus, the Sr-deficient compound shows promising behaviour for reduction of the magnetic transition temperature towards room temperature, along with an increase in the Delta S-M values, and enhancement in the electrical conductivity. Therefore, it could be possible to tune the transition temperature towards room temperature without compromising the magnetic entropy change in order to develop materials for magnetic refrigeration applications.
机译：本文研究了LA0.67SR0.33mNO3化合物中LA和SR缺乏的结构，磁性和磁热性能的影响。 X射线粉末衍射图案的RIETVELD细化证实，所有化合物都结晶成菱形晶体对称，并在BARC空间基团上用R（3）。 X射线光电子能谱测量显示，母体化合物具有Mn3 + / mn4 +的混合算命，而Mn2 + / Mn3 + / Mn4 +混合级在La和Sr缺陷的化合物的情况下发现。 LA0.67SR0.33MNO3化合物显示出365 k的磁化转变温度，而LA和SR缺陷的化合物分别表现出367 k和355 k的过渡温度。在所研究的化合物中，SR缺陷的化合物显示出552k的最高磁熵变化（Delta Sm），在352k，对于50只koe田，具有142 j的相对冷却功率（RCP） kg（-1）和3.48k的绝热温度变化，而父母和洛杉矶缺乏的化合物在364k和4.12J kg（-1）下表现出4.78J kg（-1）k-1的-delta sm K-1分别为364 k。电阻率与施加磁场的电阻率的温度依赖性揭示了La缺陷的化合物具有一个阶，并且Sr缺陷的化合物在电阻率下具有两个抑制级。因此，SR缺陷的化合物显示出用于将磁性转变温度降低到室温的有希望的行为，以及ΔS-M值的增加，以及导电性的增强。因此，可以在不影响磁熵变化的情况下使过渡温度朝着室温调谐，以便为磁制冷应用产生材料。

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