Near room-temperature magnetocaloric properties of Gd-Ga alloys

作者：Jayaraman Tanjore V^*; Boone Laura; Shield Jeffrey E

来源：Journal of Magnetism and Magnetic Materials, 2014, 363: 201-209.

DOI：10.1016/j.jmmm.2014.03.082

• Gd-Ca alloys
• Magnetic entropy change
• Refrigerant capacity

The magnetocaloric properties of Gd-Ga alloys were examined with the aim to explore their potential application as magnetic refrigerants near room-temperature. A series of Gdmo,Ga, (x=0, 5, 10, 15, and 20 at%) alloys were prepared by conventional melting and rapid solidification. Both as-cast and meltspun alloys are comprised of alpha-Gd and Gd5Ga3 with differing microstructural characteristics. While the as-cast alloys have proeutectic alpha-Ga and eutectic alpha-Ga + Gd5Ga3 (grain size -50-100 mu m), the melt-spun alloys have nanostructurect (similar to 50-100 nm) alpha-Ga. and Gd5Ga3. The Curie temperature (T-C) derived from M-T curves indicates that alloying of Ga with Gd decreases T-C. The decrease in Tc for melt-spun alloys is gradual-similar to 0.5 K per at% of Ga, and the as-cast alloys (5 <= x <= 20) have similar T-C (similar to 286 K). The saturation magnetization (Ms) derived from M-H curves (260 K), show that alloying of Ga with Gd decreases Ms. Ms for melt-spun alloys decreases from -108 emuig for Gd to similar to 42 emuig for Gd80Ga20 and for as-cast alloys Ms decreases from similar to 120 emulg for Gd to similar to 62 emu/g for Gd80Ga20. Both maximum magnetic entropy change (-Delta S-M)(max) and refrigerant capacity (RC) for as-cast and melt-spun alloys are lower than Gd (-Delta S-M)(max) decreases by similar to 1.55% and -3.0% per atomic percent of Ga in as-cast and melt-spun alloys, respectively. A steeper decrease in RC is observed in melt-spun alloys than is observed for as-cast alloys-similar to 433 J/kg for Gd to similar to 235 J/kg for Gd80Ga20 for melt spun alloys and similar to 462 J/kg for Gd to similar to 306 J/kg for Gd80Ga20 for as-cast. As-cast alloys appear to have better magnetocaloric properties than the melt-spun alloys. Alloying of diamagnetic Ga with Gd provides superior magnetocaloric properties compared to other diamagnetic elements in Group 13. The near room-temperature magnetocaloric properties of Gd-Ga alloys were comparable to a few first-order-transition based magnetic refrigerants.

• 出版日期2014-8