Recently, a massive magnetocaloric effect near the liquefaction temperature of hydrogen has been reported in the ferromagnetic material HoB₂. Here we investigate the effects of Dy substitution in the magnetocaloric properties of Ho_1-x Dy _x B₂ alloys (x = 0, 0.3, 0.5, 0.7, 1.0). We find that the Curie temperature (T _C) gradually increases upon Dy substitution, while the magnitude of the magnetic entropy change |ΔS _M| and adiabatic temperature change ΔT _ad showed a gradual decrease. On the other hand, due to the presence of successive transitions in these alloys, the peak height of the above magnetocaloric properties tends to be kept in a wide temperature range, leading to a relatively robust figure of merit in a wide temperature span. These alloys could be interesting candidates for magnetic refrigeration in the temperature range of 10 – 60 K.

近来，在铁磁材料HoB _2中已经报道了在氢的液化温度附近的大量磁热效应。在这里，我们研究了Dy置换对Ho _{1- x} Dy _x B ₂合金（x = 0、0.3、0.5、0.7、1.0）的磁热性质的影响。我们发现居里温度（T _C）在Dy取代后逐渐增加，而磁熵变的幅度| ΔS _M | 和绝热温度变化ΔT _ad 显示逐渐减少。另一方面，由于这些合金中存在连续的转变，上述磁热性质的峰高趋于保持在宽的温度范围内，从而导致在宽的温度范围内相对稳健的品质因数。这些合金可能是10 – 60 K温度范围内磁制冷的有趣候选材料。