摘要
The magnetocaloric(MC)responses of various rare-earth(RE)-dominated magnetic solids have been extensively investigated recently to develop high-performing MC materials for cryogenic cooling applications.Herein,we fabricated a family of single-phase RE-dominated magnetic ceramics,RE_(3)NbO_(7)(RE=Gd,Dy,Ho,and Er),via solid-state reactions and determined their structural and magnetic properties,specifically their cryogenic MC responses,through experiments and theoretical calculations.The prepared RE_(3)NbO_(7)ceramics all crystallize in the orthorhombic weberite-type structure(space group C2221,No.20).The constituent elements are uniformly distributed in the RE_(3)NbO_(7)ceramics and are in RE^(3+),Nb^(5+),and O^(2−)valence states.All the prepared RE_(3)NbO_(7)ceramics showed considerable cryogenic MC responses,identified by maximum magnetic entropy/temperature-averaged magnetic entropy changes and relative cooling power.Specifically,these MC parameters(ΔH=0–7 T)comprised 33.76/30.57 J/(kg K)and 362.23 J/kg for Gd3NbO7,19.39/18.72 J/(kg K)and 444.39 J/kg for Dy3NbO7,18.52/18.20 J/(kg K)and 495.9 J/kg for Ho3NbO7,and 20.26/19.31 J/(kg K)and 345.45 J/kg for Er3NbO7,respectively.These values are superior to those of RE_(3)RuO_(7) ceramics and comparable with those of recently reported RE-dominated MC materials featuring notable MC responses,indicating the promising potential of the RE_(3)NbO_(7)ceramics for cooling applications.
近年来,为了研发出高性能低温磁制冷材料并深入理解其本征的物理特性,稀土磁性固体材料的磁热效应得到了广泛而深入的研究.本文通过固相反应法制备出一系列单相稀土基磁性固体材料,即RE_(3)NbO_(7)(RE=Gd,Dy,Ho,Er)陶瓷,并通过实验测定结合理论计算对它们的晶体结构、微观组织和磁性进行了深入研究,特别是低温磁热效应RE_(3)NbO_(7)陶瓷均为正交型晶体结构(空间群C2221,No.20),其磁相变温度均低于2 K;且各组成元素均匀分布,分别以RE^(3+)、Nb^(5+)和O^(2-)价态存在.通过最大磁熵变、平均温度磁熵变和相对制冷能力分析表明,RE_(3)NbO_(7)陶瓷材料均具有比较优异的低温可逆磁热效应,其磁制冷参数明显优于RE3RuO7陶瓷,并可与最近报道的多数稀土基低温磁制冷材料相媲美,表明RE_(3)NbO_(7)陶瓷在磁制冷技术领域也具有一定的应用潜力.
基金
the Zhejiang Provincial Natural Science Foundation of China(LZ25E020002)。
