Magnetic properties and cryogenic magnetocaloric effect of pyrochlore structure RE₂Ti₂O₇ (RE = Gd, Tb, and Ho) compounds

Magnetic refrigeration technology is regarded as one of the ideal solutions for cryogenic refrigeration, while magnetocaloric materials are the crucial ones. A series of polycrystalline RE₂Ti₂O₇ (RE = Gd, Tb, and Ho) compounds were prepared by a simple one-step solid-phase reaction method in the atmosphere. The crystal structure, magnetic properties, and magnetocaloric effect (MCE) of these compounds were systematically investigated. Crystallographic research indicates that these compounds crystallized in a pyrochlore structure. Meanwhile, magnetic measurements illustrate that this class of pyrochlore oxides is highly frustrated magnetic materials and exhibits complex magnetic behavior. In addition, under the field change of 0-1 T, the values of the maximum magnetic entropy change ( − Δ S M max ) and the refrigeration capacity are calculated to be 0.9 and 5.8 J/kg for Gd₂Ti₂O₇, 9.0 and 32.9 J/kg for Tb₂Ti₂O₇, 9.9 and 29.9 J/kg for Ho₂Ti₂O₇, respectively. Therefore, RE₂Ti₂O₇ (RE = Tb and Ho) pyrochlores exhibit excellent MCEs under low magnetic fields, providing candidate materials for the application of cryogenic magnetic refrigeration technology.