Abstract Magnetic phase transitions in two Mg 2 Ni 3 Si -type of Gd2Rh3Ge and Er2Rh3Ge compounds (space group R 3 ‾ m , hR18) belonging to rhombohedral Laves phases are studied in this paper. Structural investigations using X-ray diffraction and subsequent Rietveld analysis confirm the rhombohedral R 3 ‾ m Laves phase for both compounds. Magnetization as a function of temperature, M ( T ) , identifies the ferromagnetic transition temperature in both samples with T C = 64 K and 20 K for Gd2Rh3Ge and Er2Rh3Ge respectively which is supported by the specific heat, C p ( T ) . Arrott plots, universal scaling curves by normalizing magnetic entropy changes ( Δ S m ) and field dependent Δ S m revealed that both compounds undergo second order ferromagnetic phase transitions at T C . Significant magnetocaloric effect (MCE) is observed for both compounds, attaining a value of 12 J kg−1 K−1 at T = 64 K, H = 7 T for Gd2Rh3Ge and 11 J kg−1 K−1 at T = 20 K, H = 7 T for Er2Rh3Ge. The adiabatic temperature change is 5.9 K for Gd2Rh3Ge and 10.5 K for Er2Rh3Ge for H = 7 T.

中文翻译：

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Gd2Rh3Ge和Er2Rh3Ge三元菱形Laves相的磁相变和磁热效应

摘要 本文研究了属于菱面体Laves 相的两种Mg 2 Ni 3 Si 型Gd2Rh3Ge 和Er2Rh3Ge 化合物（空间群R 3 ‾ m , hR18）的磁相变。使用 X 射线衍射和随后的 Rietveld 分析进行的结构研究证实了两种化合物的菱形 R 3 ‾ m Laves 相。作为温度函数的磁化 M ( T ) 确定了两个样品中的铁磁转变温度，Gd2Rh3Ge 和 Er2Rh3Ge 的 TC = 64 K 和 20 K，由比热 C p ( T ) 支持。阿罗特图、通过归一化磁熵变 (ΔSm) 和场相关的 ΔSm 得到的通用标度曲线表明，这两种化合物在 TC 处都经历了二阶铁磁相变。两种化合物均观察到显着的磁热效应 (MCE)，在 T = 64 K 时达到 12 J kg-1 K-1，Gd2Rh3Ge 的 H = 7 T 和在 T = 20 K 时达到 11 J kg-1 K-1，Er2Rh3Ge 的 H = 7 T。Gd2Rh3Ge 的绝热温度变化为 5.9 K，H = 7 T 时 Er2Rh3Ge 的绝热温度变化为 10.5 K。