The phases and magnetocaloric effect in the alloys （Gd1-xNdx）Co2 with x = 0, 0.1, 0.2, 0.3, and 0.4 were investigated by X-ray diffraction analysis and magnetization measurement. The samples are single phase with a ...The phases and magnetocaloric effect in the alloys （Gd1-xNdx）Co2 with x = 0, 0.1, 0.2, 0.3, and 0.4 were investigated by X-ray diffraction analysis and magnetization measurement. The samples are single phase with a cubic MgCu2-type structure. The To decreases obviously with increasing Nd content from 404 K of the alloy with x = 0 to 272 K of the alloy with x = 0.4; forx = 0.3, the To is 296 K, which is near room temperature. In the samples （Gd1-xNdx）Co2 with x = 0.0, 0.1, 0.2, 0.3, and 0.4, the maximum magnetic entropy change is 1.471, 1.228, 1.280, 1.381 and 1.610 J·kg^-1·K^-1, respectively, in the applied field range of 0-2.0 T. The results of Arrott plots confirmed that the transition type were second order magnetic transition forx = 0, 0.3, and 0.4.展开更多
In this paper, we study the effects of Pr substitution on the hydrogenating process and magnetocaloric properties of La（1-x）PrxFe11.4Si1.6Hy hydrides. The powder x-ray diffraction patterns of the La1-xPrxFe11.4Si1.6...In this paper, we study the effects of Pr substitution on the hydrogenating process and magnetocaloric properties of La（1-x）PrxFe11.4Si1.6Hy hydrides. The powder x-ray diffraction patterns of the La1-xPrxFe11.4Si1.6 and its hydrides show that each of the alloys is crystallized into the single phase of cubic Na Zn13-type structure. There are hydrogen-absorbing plateaus under 0.4938 MPa and 0.4882 MPa in the absorbing curves for the La0.8Pr0.2Fe11.4Si1.6 and La0.6Pr0.4Fe11.4Si1.6 compounds. The releasing processes lag behind the absorbing process, which is obviously different from the coincidence between absorbing and releasing curves of the La Fe11.4Si1.6 compound. The remnant hydrogen content for La0.6Pr0.4Fe11.4Si1.6 is significantly more than that for La0.8Pr0.2Fe11.4Si1.6 after hydrogen desorption, indicating that more substitutions of Pr for La are beneficial to retaining more hydrogen atoms in the alloys. The values of maximum magnetic entropy change are 14.91 J/kg·K and 17.995 J/kg·K for La0.8Pr0.2Fe11.4Si1.6H0.13 and La0.6Pr0.4Fe11.4Si1.6H0.87,respectively.展开更多
The phases and the magnetocaloric effect in the alloys R（Co1-xSnx）2 with X = 0, 0.025, 0.050, 0.075, and 0.100 were investigated by X-ray diffraction analysis and magnetization measurement. The substitution of Sn in...The phases and the magnetocaloric effect in the alloys R（Co1-xSnx）2 with X = 0, 0.025, 0.050, 0.075, and 0.100 were investigated by X-ray diffraction analysis and magnetization measurement. The substitution of Sn in RCo2 is limited. The cubic MgCu2-type structure for the alloys of RCo2 was confirmed by X-ray powder diffraction and the remaining alloys mainly consisted of the RCo2 phase, along with some RCo3 and R5Sn3 impurity phases. The impurity phases increase with the increase of Sn content. The Tc of the alloys is not very sensitive to the Sn substitution for Dy（Co1-xSnx）2 and Tb（Co1-xSnx）2, whereas in Gd（Co1-xSnx）2, the Curie temperatures significantly increase. The maximum magnetic entropy changes in the alloys Dy（Co1-xSnx）2 （x = 0, 0.025, 0.050, 0.075） are 5.78, 5.43, 3.88, and 2.98 J·kg^-1·K^-1, respectively, and those in the Tb（Co1-xSnx）2 （x = 0, 0.025） are 3.44, and 2.29 J·kg^-1·K^-1 respectively in the applied field change of 0-2.0 T.展开更多
d-Al-Dy system materials were prepared by the technique of powder sintering. Twolayers gradient function materials with compositions of (Gd_0.9Dy_0.1)_3Al_2 and Gd_3Al_2 respectively were studied. The results show tha...d-Al-Dy system materials were prepared by the technique of powder sintering. Twolayers gradient function materials with compositions of (Gd_0.9Dy_0.1)_3Al_2 and Gd_3Al_2 respectively were studied. The results show that the Curie temperature (Tc) of the monolayer material decreases with the increment of Dy content. The Tc values of the twolayer gradient function material agree well with the layer numbers and corresponding to Dy content. For the Tc gradiently changed twolayers Gd-Al-Dy system material, its ΔSm changes smoothly with temperature. Therefore, the magnetic refrigeration is improved.展开更多
Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measuremen...Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measurement. The samples were single phase with cubic MgCu2- type structure; with the increase of Dy content, Tc decreased from 240 K （TbCo2） to 130 K （DyCo2）, and the maximum magnetic entropy change ｜ △SM,max｜ increased from 3.133 to 8.176 J/kg-K under low magnetic field of 0-2 T. The Arrott plot and the change of ｜△SM,max｜ showed that magnetic phase transition from second order to first order occured with the increase of Dy content between x=-0.6 and 0.8.展开更多
The phases in the compounds （Gd1-xCex）Co2 with x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 were investigated by X-ray diffraction, and the magnetocaloric effect for x = 0-0.4 was studied by magnetization measurements. The sa...The phases in the compounds （Gd1-xCex）Co2 with x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 were investigated by X-ray diffraction, and the magnetocaloric effect for x = 0-0.4 was studied by magnetization measurements. The samples are almost single phase with a cubic MgCu2-type structure for x = 0-0.5. The magnetization decreases with an increase in Ce content. There is almost no magnetic transition for x = 0.5 at 100-350 K. The Curie temperature （To） of the （Gd1-xCex）Co2compounds with x from 0.1 to 0.4 are 350, 344, 340, and 338 K respectively. The maximum magnetic entropy change is 2.34 J·kg^-1·K^-1 when x = 0.3. The results of Arrott plots show that the magnetic phase transition is second-order magnetic phase transition in these compounds.展开更多
基金the National Natu-ral Science Foundation of China (No. 50371058)
文摘The phases and magnetocaloric effect in the alloys （Gd1-xNdx）Co2 with x = 0, 0.1, 0.2, 0.3, and 0.4 were investigated by X-ray diffraction analysis and magnetization measurement. The samples are single phase with a cubic MgCu2-type structure. The To decreases obviously with increasing Nd content from 404 K of the alloy with x = 0 to 272 K of the alloy with x = 0.4; forx = 0.3, the To is 296 K, which is near room temperature. In the samples （Gd1-xNdx）Co2 with x = 0.0, 0.1, 0.2, 0.3, and 0.4, the maximum magnetic entropy change is 1.471, 1.228, 1.280, 1.381 and 1.610 J·kg^-1·K^-1, respectively, in the applied field range of 0-2.0 T. The results of Arrott plots confirmed that the transition type were second order magnetic transition forx = 0, 0.3, and 0.4.
基金supported by the National Natural Science Foundation of China(Grant Nos.51301008 and 51171003)the Beijing Natural Science Foundation,China(Grant No.1112005)
文摘In this paper, we study the effects of Pr substitution on the hydrogenating process and magnetocaloric properties of La（1-x）PrxFe11.4Si1.6Hy hydrides. The powder x-ray diffraction patterns of the La1-xPrxFe11.4Si1.6 and its hydrides show that each of the alloys is crystallized into the single phase of cubic Na Zn13-type structure. There are hydrogen-absorbing plateaus under 0.4938 MPa and 0.4882 MPa in the absorbing curves for the La0.8Pr0.2Fe11.4Si1.6 and La0.6Pr0.4Fe11.4Si1.6 compounds. The releasing processes lag behind the absorbing process, which is obviously different from the coincidence between absorbing and releasing curves of the La Fe11.4Si1.6 compound. The remnant hydrogen content for La0.6Pr0.4Fe11.4Si1.6 is significantly more than that for La0.8Pr0.2Fe11.4Si1.6 after hydrogen desorption, indicating that more substitutions of Pr for La are beneficial to retaining more hydrogen atoms in the alloys. The values of maximum magnetic entropy change are 14.91 J/kg·K and 17.995 J/kg·K for La0.8Pr0.2Fe11.4Si1.6H0.13 and La0.6Pr0.4Fe11.4Si1.6H0.87,respectively.
基金The work was financially supported by the National Natural Science Foundation of China (No. 50371058).
文摘The phases and the magnetocaloric effect in the alloys R（Co1-xSnx）2 with X = 0, 0.025, 0.050, 0.075, and 0.100 were investigated by X-ray diffraction analysis and magnetization measurement. The substitution of Sn in RCo2 is limited. The cubic MgCu2-type structure for the alloys of RCo2 was confirmed by X-ray powder diffraction and the remaining alloys mainly consisted of the RCo2 phase, along with some RCo3 and R5Sn3 impurity phases. The impurity phases increase with the increase of Sn content. The Tc of the alloys is not very sensitive to the Sn substitution for Dy（Co1-xSnx）2 and Tb（Co1-xSnx）2, whereas in Gd（Co1-xSnx）2, the Curie temperatures significantly increase. The maximum magnetic entropy changes in the alloys Dy（Co1-xSnx）2 （x = 0, 0.025, 0.050, 0.075） are 5.78, 5.43, 3.88, and 2.98 J·kg^-1·K^-1, respectively, and those in the Tb（Co1-xSnx）2 （x = 0, 0.025） are 3.44, and 2.29 J·kg^-1·K^-1 respectively in the applied field change of 0-2.0 T.
文摘d-Al-Dy system materials were prepared by the technique of powder sintering. Twolayers gradient function materials with compositions of (Gd_0.9Dy_0.1)_3Al_2 and Gd_3Al_2 respectively were studied. The results show that the Curie temperature (Tc) of the monolayer material decreases with the increment of Dy content. The Tc values of the twolayer gradient function material agree well with the layer numbers and corresponding to Dy content. For the Tc gradiently changed twolayers Gd-Al-Dy system material, its ΔSm changes smoothly with temperature. Therefore, the magnetic refrigeration is improved.
文摘Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measurement. The samples were single phase with cubic MgCu2- type structure; with the increase of Dy content, Tc decreased from 240 K （TbCo2） to 130 K （DyCo2）, and the maximum magnetic entropy change ｜ △SM,max｜ increased from 3.133 to 8.176 J/kg-K under low magnetic field of 0-2 T. The Arrott plot and the change of ｜△SM,max｜ showed that magnetic phase transition from second order to first order occured with the increase of Dy content between x=-0.6 and 0.8.
文摘The phases in the compounds （Gd1-xCex）Co2 with x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 were investigated by X-ray diffraction, and the magnetocaloric effect for x = 0-0.4 was studied by magnetization measurements. The samples are almost single phase with a cubic MgCu2-type structure for x = 0-0.5. The magnetization decreases with an increase in Ce content. There is almost no magnetic transition for x = 0.5 at 100-350 K. The Curie temperature （To） of the （Gd1-xCex）Co2compounds with x from 0.1 to 0.4 are 350, 344, 340, and 338 K respectively. The maximum magnetic entropy change is 2.34 J·kg^-1·K^-1 when x = 0.3. The results of Arrott plots show that the magnetic phase transition is second-order magnetic phase transition in these compounds.
