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Magnetocaloric Effect, Electric, and Dielectric Properties of Nd 0.6 Sr 0.4 Mn x Co 1-x O 3 Composites
Journal of Magnetism and Magnetic Materials ( IF 2.7 ) Pub Date : 2018-07-01 , DOI: 10.1016/j.jmmm.2018.02.087
I.A. Abdel-Latif , A.M. Ahmed , H.F. Mohamed , S.A. Saleh , J.A. Paixão , Kh.A. Ziq , M.Kh. Hamad , E.G. Al-Nahari , M. Ghozza , S. Allam

Abstract The magnetocaloric effect (MCE) and electric-dielectric properties of the Nd-cobaltate perovskites Nd0.6Sr0.4Co1−xMnxO3 (x = 0, 0.3, 0.7 and 1) were investigated for possible use in magnetic cooling applications. Upon Mn substitution, the magnetic exchange interaction is affected by the (Mn4+/Mn3+) ratio, which in turn impacts several physical properties. The XRD patterns of the synthesized composites revealed a single phase with an orthorhombic structure with space group Pbnm (62). The orthorhombic lattice distortion increases linearly with the Mn content, reaching a maximum value (D = 7.377 × 10−3) for Nd0.6Sr0.4MnO3. The temperature and frequency dependence of the dielectric permittivity was studied and analyzed using Maxwell-Wagner interfacial polarization and Koops phenomenological theory. The rapid increase in magnetic susceptibility around the paramagnetic (PM)–ferromagnetic (FM) transition temperature TC is greatly affected by Mn substitution. The decrease in susceptibility with increasing temperature can be attributed to a charge ordering effect. The PM-FM transition occurs in the temperature range of 150–200 K. Moreover, the presence of spontaneous magnetization with second-order phase transitions is observed from Arrott plot isotherms. The MCE was also investigated by determining ΔSM and the relative cooling power (RCP), and the maximum value is found for Nd0.6Sr0.4Co0.3 Mn0.7O3. These results compare favorably with those reported for similar materials, indicating our materials as a possible candidate for use in magnetocaloric refrigerators.

中文翻译:

Nd 0.6 Sr 0.4 Mn x Co 1-x O 3 复合材料的磁热效应、电学和介电性能

摘要 研究了 Nd-钴酸钙钛矿 Nd0.6Sr0.4Co1-xMnxO3 (x = 0, 0.3, 0.7 和 1) 的磁热效应 (MCE) 和电介电特性,以用于磁冷却应用。Mn 取代后,磁交换相互作用受 (Mn4+/Mn3+) 比的影响,进而影响多种物理性质。合成的复合材料的 XRD 图案显示具有正交结构的单相,空间群为 Pbnm (62)。正交晶格畸变随 Mn 含量线性增加,Nd0.6Sr0.4MnO3 达到最大值(D = 7.377 × 10-3)。使用 Maxwell-Wagner 界面极化和 Koops 现象学理论研究和分析介电常数的温度和频率依赖性。顺磁 (PM)-铁磁 (FM) 转变温度 TC 附近磁化率的快速增加受 Mn 取代的影响很大。随着温度升高,磁化率降低可归因于电荷排序效应。PM-FM 转变发生在 150-200 K 的温度范围内。此外,从 Arrott 曲线等温线观察到自发磁化和二阶相变的存在。还通过确定 ΔSM 和相对冷却功率 (RCP) 来研究 MCE,发现最大值是 Nd0.6Sr0.4Co0.3 Mn0.7O3。这些结果与报告的类似材料的结果相比更胜一筹,表明我们的材料可能是用于磁热冰箱的候选材料。
更新日期:2018-07-01
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