In this study,a novel method is proposed for producing perovskite rare-earth manganese oxide magnetic refrigeration materials that exhibit superior properties compared to similar materials.The maximum magnetic entropy...In this study,a novel method is proposed for producing perovskite rare-earth manganese oxide magnetic refrigeration materials that exhibit superior properties compared to similar materials.The maximum magnetic entropy change values for this sample are 1.44 and 3.75 J·kg-1·K^(-1)for magnetic fields of 2 and 7 T,respectively.Additionally,its relative cooling power has been calculated to be 101.96 and 404.78 J·kg^(-1),indicating good performance.Both results were obtained using the sample synthesized under a pressure of 4 GPa,and the sample has undergone a second phase transition.The critical behavior of the sample fits well with the mean field model.For different magnetic fields,there is a significant overlap between the values of the maximum magnetic entropy change and the temperature-averaged entropy change,indicating that the refrigeration performance of the sample after high pressure can approach its maximum capability.展开更多
Atomic-scale oxidation dynamics of Cu2O nanocrystallines （NCs） are directly observed by in situ high-resolution transmission electron microscopy. A two-stage oxidation process is observed： （1）The initial oxidatio...Atomic-scale oxidation dynamics of Cu2O nanocrystallines （NCs） are directly observed by in situ high-resolution transmission electron microscopy. A two-stage oxidation process is observed： （1）The initial oxidation stage is dominated by the dislocation-mediated oxidation behavior of Cu2O NCs via solid-solid transformations, leading to the formation of a new intermediate CuOx phase. The possible crystal structure of the CuOx phase is discussed. （2） Subsequently, CuOx is transformed into CuO by layer-by-layer oxidation. These results will help in understanding the oxidation mechanisms of copper oxides and pave the way for improving their structural diversity and exploiting their potential industrial applications.展开更多
基金supported by the State Key Development Program for Basic Research of China(51562032)and the 2021 Intramural Project(30234013)。
文摘In this study,a novel method is proposed for producing perovskite rare-earth manganese oxide magnetic refrigeration materials that exhibit superior properties compared to similar materials.The maximum magnetic entropy change values for this sample are 1.44 and 3.75 J·kg-1·K^(-1)for magnetic fields of 2 and 7 T,respectively.Additionally,its relative cooling power has been calculated to be 101.96 and 404.78 J·kg^(-1),indicating good performance.Both results were obtained using the sample synthesized under a pressure of 4 GPa,and the sample has undergone a second phase transition.The critical behavior of the sample fits well with the mean field model.For different magnetic fields,there is a significant overlap between the values of the maximum magnetic entropy change and the temperature-averaged entropy change,indicating that the refrigeration performance of the sample after high pressure can approach its maximum capability.
基金This work was supported by the National Basic Research Program of China （No. 2011CB933300）, the National Natural Science Foundation of China （Nos. 51671148, 51271134, J1210061, 11674251, 51501132, and 51601132）, the Hubei Provincial Natural Science Foundation of China （Nos. 2016CFB446 and 2016CFB155）, the Fundamental Research Funds for the Central Universities, and the CERS-1-26 （CERS-China Equip- ment and Education Resources System）, and the China Postdoctoral Science Foundation （No. 2014T70734）, and the Open Research Fund of Science and Technology on High Strength Structural Materials Laboratory （Central South University） and the Suzhou Science and Technology project （No. SYG201619）.
文摘Atomic-scale oxidation dynamics of Cu2O nanocrystallines （NCs） are directly observed by in situ high-resolution transmission electron microscopy. A two-stage oxidation process is observed： （1）The initial oxidation stage is dominated by the dislocation-mediated oxidation behavior of Cu2O NCs via solid-solid transformations, leading to the formation of a new intermediate CuOx phase. The possible crystal structure of the CuOx phase is discussed. （2） Subsequently, CuOx is transformed into CuO by layer-by-layer oxidation. These results will help in understanding the oxidation mechanisms of copper oxides and pave the way for improving their structural diversity and exploiting their potential industrial applications.
