Thermal and magnetic properties of regenerator material Gd2O2S
Thermal and magnetic properties of regenerator material Gd2O2S
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DOI：
10.1088/1742-6596/897/1/012010
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发表时间：
2017-09
期刊：
影响因子：
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通讯作者：
K. Matsumoto;T. Numazawa;Y. Ura;T. Ujiyama;S. Abe
中科院分区：
文献类型：
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作者：
K. Matsumoto;T. Numazawa;Y. Ura;T. Ujiyama;S. Abe
磁性材料在改善再生式制冷机性能方面发挥着重要作用，因为它们在磁转变温度下具有高体积比热。硫氧化钆（Gd2O2S，GOS）在 5 K 时具有反铁磁转变，当其用于工作温度低于 10 K 的第二级蓄热器的冷侧时，可改善制冷器的冷却性能。较小的磁化率和对磁场不敏感的比热对于减少磁场对制冷器性能的影响非常重要。我们测量了陶瓷 GOS 在高达 5 T 的磁场中的磁化强度和比热。GOS 的磁化强度代表了反铁磁材料的典型温度依赖性，并且没有观察到变磁转变。至于GOS的比热，随着磁场从0T增加到5T，峰值温度从5.5K降低到5.0K，并且磁场中的转变仍然很尖锐。据观察，GOS 的热导率对磁场的依赖性非常小。
Magnetic materials play a significant role in improvement of regenerative cryocooler performance, because they have high volumetric specific heat at magnetic transition temperatures. Gadolinium oxysulfide (Gd2O2S, GOS) that has an antiferromagnetic transition at 5 K improved the cooling performance of cryocoolers when it was used in colder side of the second stage regenerator operating below 10 K. Small magnetic susceptibility and specific heat insensitive to magnetic field is important in order to reduce influence of magnetic field on the performance of cryocooler. We measured magnetization and specific heat of ceramic GOS in magnetic field up to 5 T. The magnetization of GOS represented typical temperature dependence for antiferromagnetic materials and no metamagnetic transition was observed. As for specific heat of GOS, peak temperature decreased from 5.5 to 5.0 K with increasing magnetic field from 0 to 5 T and the transitions remained sharp in magnetic fields. Thermal conductivity of GOS was observed to have very small magnetic field dependence.