In this study,zirconium(Zr) successfully substituted for erbium(Er) in Er_(6-x)Zr_(x)MnSb_(2)(x=0,0.5,1,1.5) of the Fe_(2)P type,with comprehensive characterizations on crystal structure,electronic structure and magne...In this study,zirconium(Zr) successfully substituted for erbium(Er) in Er_(6-x)Zr_(x)MnSb_(2)(x=0,0.5,1,1.5) of the Fe_(2)P type,with comprehensive characterizations on crystal structure,electronic structure and magnetic properties.According to synchrotron powder X-ray diffraction data analysis and density functional theory calculation,Zr does not randomly but preferentially occupy during the doping process and results in weaker magnetic exchange interactions and depressed ordering temperatures.The electronic structure data show that the doping of Zr can weaken interaction between Er and Mn atoms.Owing to multiple transitions,the Er_(6-x)Zr_(x)MnSb_(2)(x=0,0.5,1,1.5) exhibit table-like magnetocaloric effect.Er_(6)MnSb_(2) displays wide δT_(FWHM)(full width at half maximum of the magnetic entropy change curve) of 116 K and high relative cooling power of 388.62 J/kg for 3 T.The maximum magnetic entropy change of Er_(6-x)Zr_(x)MnSb_(2) is increased from 3.81 to 7.69 J/(kg·K) with the Zr content up from x=0 to x=1.5.展开更多
Rare earth Er^(3+)doped(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)(x=0.1,0.2,and 0.3)ceramic samples were synthesized using a solid state reaction method.The microstructure and thermal properties of these ceramics were investigat...Rare earth Er^(3+)doped(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)(x=0.1,0.2,and 0.3)ceramic samples were synthesized using a solid state reaction method.The microstructure and thermal properties of these ceramics were investigated to evaluate their potential as thermal barrier coating materials.The results show that ceramics are compact with regular-shaped grains of 1-5μm size.(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)has a pyrochlore structure mainly determined by ionic radius ratio,but the ordering degree decreases with increase of the Er_(2)O_(3)content.There is no phase transformation from 1000 to 1200℃,and the(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics exhibit excellent phase stability during thermal treatment at 1200℃for 100 h and 1400℃for 50 h.The thermal conductivities of dense(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics range from 1.52 to 1.59 W/(m·K),which is lower than that of Sm_(2)Zr_(2)O_(7),and decrease as the Er2O3content increases.Besides,the thermal expansion coefficient of(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)is higher than that of Sm_(2)Zr_(2)O_(7).展开更多
基金Project supported by the National Natural Science Foundation of China (51861003)the Research Grants Council of Hong Kong(17208120)。
文摘In this study,zirconium(Zr) successfully substituted for erbium(Er) in Er_(6-x)Zr_(x)MnSb_(2)(x=0,0.5,1,1.5) of the Fe_(2)P type,with comprehensive characterizations on crystal structure,electronic structure and magnetic properties.According to synchrotron powder X-ray diffraction data analysis and density functional theory calculation,Zr does not randomly but preferentially occupy during the doping process and results in weaker magnetic exchange interactions and depressed ordering temperatures.The electronic structure data show that the doping of Zr can weaken interaction between Er and Mn atoms.Owing to multiple transitions,the Er_(6-x)Zr_(x)MnSb_(2)(x=0,0.5,1,1.5) exhibit table-like magnetocaloric effect.Er_(6)MnSb_(2) displays wide δT_(FWHM)(full width at half maximum of the magnetic entropy change curve) of 116 K and high relative cooling power of 388.62 J/kg for 3 T.The maximum magnetic entropy change of Er_(6-x)Zr_(x)MnSb_(2) is increased from 3.81 to 7.69 J/(kg·K) with the Zr content up from x=0 to x=1.5.
基金Project supported by the National High Technology Research and Development Program of China(2015AA034403)National Natural Science Foundation of China(51762036)The Science and Technology Program of Inner Mongolia(2019)。
文摘Rare earth Er^(3+)doped(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)(x=0.1,0.2,and 0.3)ceramic samples were synthesized using a solid state reaction method.The microstructure and thermal properties of these ceramics were investigated to evaluate their potential as thermal barrier coating materials.The results show that ceramics are compact with regular-shaped grains of 1-5μm size.(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)has a pyrochlore structure mainly determined by ionic radius ratio,but the ordering degree decreases with increase of the Er_(2)O_(3)content.There is no phase transformation from 1000 to 1200℃,and the(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics exhibit excellent phase stability during thermal treatment at 1200℃for 100 h and 1400℃for 50 h.The thermal conductivities of dense(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)ceramics range from 1.52 to 1.59 W/(m·K),which is lower than that of Sm_(2)Zr_(2)O_(7),and decrease as the Er2O3content increases.Besides,the thermal expansion coefficient of(Sm_(1-x)Er_(x))_(2)Zr_(2)O_(7)is higher than that of Sm_(2)Zr_(2)O_(7).
