The crystal structures and magnetic properties of novel Eu TrGa3-r （T=Pd, It, Rh） in termetallic compounds are investigated by using powder x-ray diffraction and magnetic measurements. EuTrGa3-r crystallizes in orth...The crystal structures and magnetic properties of novel Eu TrGa3-r （T=Pd, It, Rh） in termetallic compounds are investigated by using powder x-ray diffraction and magnetic measurements. EuTrGa3-r crystallizes in orthorhombic structure with space group of Cmcm and Z = 4. There are four kinds of nonequivalent 4c crystal positions in EuTrGaa-r unit cell, which are occupied by 4Eu, 4GaⅠ, 4（GaⅡ, T） and 4GaⅢ, respectively. EuTrGa3-r ex- hibits the complex magnetic states in low-temperature regime, with the three-, two- and one-antiferromagnetic transitions occurring for T=Ir, T=Rh and T=Pd, respectively. It might be due to the Kondo effect： a localized antiferromagnetic interaction of the isolated impurity spins with the surrounding conduction electrons at low-temperature regime.展开更多
A nano-laminated Y_(3)Si_(2)C_(2) ceramic material was successfully synthesized via an in situ reaction between YH_(2)and SiC using spark plasma sintering technology.A MAX phase-like ternary layered structure of Y_(3)...A nano-laminated Y_(3)Si_(2)C_(2) ceramic material was successfully synthesized via an in situ reaction between YH_(2)and SiC using spark plasma sintering technology.A MAX phase-like ternary layered structure of Y_(3)Si_(2)C_(2) was observed at the atomic-scale by high resolution transmission electron microscopy.The lattice parameters calculated from both X-ray diffraction and selected area electron diffraction patterns are in good agreement with the reported theoretical results.The nano-laminated fracture of kink boundaries,delamination,and slipping were observed at the tip of the Vickers indents.The elastic modulus and Vickers hardness of Y_(3)Si_(2)C_(2) ceramics(with 5.5 wt%Y_(2)O_(3)) sintered at 1500℃were 156 and 6.4 GPa,respectively.The corresponding values of thermal and electrical conductivity were 13.7 W·m^(-1)·K^(-1) and 6.3×10^(5)S·m^(-1),respectively.展开更多
Fe_(2)AlB_(2) powder material was prepared by the direct reaction of iron,aluminum and boron powders in a tubular furnace.The effects of different Al contents,temperature and raw material pretreatment on the purity of...Fe_(2)AlB_(2) powder material was prepared by the direct reaction of iron,aluminum and boron powders in a tubular furnace.The effects of different Al contents,temperature and raw material pretreatment on the purity of product were studied.The mixed powder with the stoichiometric ratio of 1.5Al/2Fe/2B was processed by CIP (Cold Isostatic Pressing),and then calcined at 1150℃ for 120 min.The product containing a small amount of impurities is treated with alkaline solution to obtain high-purity Fe_(2)Al B_(2) powder.Zr B_(2)-Fe_(2)Al B_(2) composite ceramic was successfully prepared at 1250℃ by hot pressing sintering.The density,hardness and fracture toughness were 96.2%,22±0.3 GPa and 5.78±0.5 MPa·m^(1/2),respectively.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11274110
文摘The crystal structures and magnetic properties of novel Eu TrGa3-r （T=Pd, It, Rh） in termetallic compounds are investigated by using powder x-ray diffraction and magnetic measurements. EuTrGa3-r crystallizes in orthorhombic structure with space group of Cmcm and Z = 4. There are four kinds of nonequivalent 4c crystal positions in EuTrGaa-r unit cell, which are occupied by 4Eu, 4GaⅠ, 4（GaⅡ, T） and 4GaⅢ, respectively. EuTrGa3-r ex- hibits the complex magnetic states in low-temperature regime, with the three-, two- and one-antiferromagnetic transitions occurring for T=Ir, T=Rh and T=Pd, respectively. It might be due to the Kondo effect： a localized antiferromagnetic interaction of the isolated impurity spins with the surrounding conduction electrons at low-temperature regime.
基金the support from the Ningbo 3315 Innovative Teams Program,China(Grant No.2019A-14-C)This study was supported by the National Natural Science Foundation of China(Grant Nos.11975296 and 51811540402).
文摘A nano-laminated Y_(3)Si_(2)C_(2) ceramic material was successfully synthesized via an in situ reaction between YH_(2)and SiC using spark plasma sintering technology.A MAX phase-like ternary layered structure of Y_(3)Si_(2)C_(2) was observed at the atomic-scale by high resolution transmission electron microscopy.The lattice parameters calculated from both X-ray diffraction and selected area electron diffraction patterns are in good agreement with the reported theoretical results.The nano-laminated fracture of kink boundaries,delamination,and slipping were observed at the tip of the Vickers indents.The elastic modulus and Vickers hardness of Y_(3)Si_(2)C_(2) ceramics(with 5.5 wt%Y_(2)O_(3)) sintered at 1500℃were 156 and 6.4 GPa,respectively.The corresponding values of thermal and electrical conductivity were 13.7 W·m^(-1)·K^(-1) and 6.3×10^(5)S·m^(-1),respectively.
基金supported by the grants of CAS Priority Research Program(XDB20010300,XDA21010204)Science and Technology Program of Fujian Province(2017T3001)。
文摘Fe_(2)AlB_(2) powder material was prepared by the direct reaction of iron,aluminum and boron powders in a tubular furnace.The effects of different Al contents,temperature and raw material pretreatment on the purity of product were studied.The mixed powder with the stoichiometric ratio of 1.5Al/2Fe/2B was processed by CIP (Cold Isostatic Pressing),and then calcined at 1150℃ for 120 min.The product containing a small amount of impurities is treated with alkaline solution to obtain high-purity Fe_(2)Al B_(2) powder.Zr B_(2)-Fe_(2)Al B_(2) composite ceramic was successfully prepared at 1250℃ by hot pressing sintering.The density,hardness and fracture toughness were 96.2%,22±0.3 GPa and 5.78±0.5 MPa·m^(1/2),respectively.
