Abstract The effects of Ta substitution on the phase transition have been studied in Hf1-xTaxFe1.98 (x=0.125, 0.13, 0.135) alloys with kagome-type lattice. Increased Ta substitution leads into the reduced metamagnetic transition temperature (Tt). The nature of such phase transition is also changed from second-order type to the weak first-order one, suggested by the gradually observed hysteresis. The magnetic entropy change (ΔS) is meanwhile enhanced from 3.04 Jkg-1K-1 to 3.4 Jkg-1K-1. Such enhanced magnetocaloric effects are strongly correlated with the enhanced magneto-elastic effect, which is further confirmed by the maximized saturation magnetostriction (λs//) of ∼1700 ppm near the Tt of Hf0.865Ta0.135Fe1.98 alloy. The concurrence of maximized ΔSmax and λs// suggests the strong magneto-elastic coupling during phase transition and the high linear co-efficiency of negative thermal expansion can be triggered in Fe-deficient Hf0.865Ta0.135Fe1.98 alloy.

中文翻译：

---

(Hf,Ta)Fe1.98 Laves 相中的相变诱导磁弹性耦合和负热膨胀

摘要 在具有kagome 型晶格的Hf1-xTaxFe1.98 (x=0.125, 0.13, 0.135) 合金中研究了Ta 取代对相变的影响。增加的 Ta 取代导致降低的变磁转变温度 (Tt)。逐渐观察到的滞后表明，这种相变的性质也从二阶类型变为弱一阶类型。同时，磁熵变 (ΔS) 从 3.04 Jkg-1K-1 增强到 3.4 Jkg-1K-1。这种增强的磁热效应与增强的磁弹性效应密切相关，Hf0.865Ta0.135Fe1.98 合金的 Tt 附近约 1700 ppm 的最大饱和磁致伸缩 (λs//) 进一步证实了这一点。