La1-zNdz(Fe0.88Si0.12)13 and their hydrides were investigated to obtain large magnetocaloric effects (MCEs) in a wide temperature range, including room temperature, for applications in magnetic refrigents. Since the magnetization change due to the itinerant-electron metamagentic (IEM) transition for La1-zNdz(Fe0.88Si0.12)13 becomes larger with increasing z, the isothermal magnetic entropy change ΔSm and the relative cooling power (RCP) are enhanced. In addition, the Curie temperatrue TC of La0.8Nd0.2(Fe0.88Si0.12)13 is increased from 193 to 319 K by hydrogen absorption, with the IEM transition. The maximum value of -ΔSm,-ΔSm max, in a magnetic field change of 2 T for La0.8Nd0.2(Fe0.88Si0.12)13H1.1 is about 23 J/kg K at TC=288 K, which is larger than that of 19 J/ kg K at TC=276 K for La(Fe0.88Si0.12)13H1.0. The value of RCP=179 J/kg of the former is also larger than 160 J/ kg of the latter. It is concluded that the partial substitution of Nd improves MCEs in a wide temperautre range, including room temperature.
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