The effects of different Bi contents on the properties of Sn solders were studied. The interfacial reaction and growth behavior of intermetallic compounds（IMCs） layer（η-Cu6 Sn5 + e-Cu3 Sn） for various soldering t...The effects of different Bi contents on the properties of Sn solders were studied. The interfacial reaction and growth behavior of intermetallic compounds（IMCs） layer（η-Cu6 Sn5 + e-Cu3 Sn） for various soldering time and the influence of Bi addition on the thermal behavior of Sn-x Bi solder alloys were investigated. The Cu6 Sn5 IMC could be observed as long as the molten solder contacted with the Cu substrate. However, with the longer welding time such as 60 and 300 s, the Cu3 Sn IMC was formed at the interface between Cu6 Sn5 and Cu substrate. With the increase of soldering time, the thickness of total IMCs increased, meanwhile, the grain size of Cu6 Sn5 also increased. An appropriate amount of Bi element was beneficial for the growth of total IMCs,but excessive Bi（≥ 5 wt%） inhibited the growth of Cu6 Sn5 and Cu3 Sn IMC in Sn-x Bi/Cu microelectronic interconnects. Furthermore, with the Bi contents increasing（Sn-10 Bi solder in this present investigation）, some Bi particles accumulated at the interface between Cu6 Sn5 layer and the solder.展开更多
Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure ...Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure is composed of two different types of polyhedral slabs.Slab-I is a galena-like structure motif that forms with[MSe_(6)](M=Pb,Sb,and Bi)octahedra and slab-Ⅱcontains one octahedral[MSe_(6)]block and paired squared pyramids[MSe_(5)].Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)exhibits n-type semiconductor behaviors and the remarkable Seebeck coefficient from-64.1μV K^(-1)for x=0 sample to-242μV K^(-1)forx=4 sample at 300 K.Moreover,the Pb_(5)Sb_(12)Bi_(6)Se_(32)has the highest carrier concentration of 1.35×10^(20)cm^(-3)in pavonite-type materials.The complex compositions,mixed occupancies of the cations,and quasi-two-dimensional structure lead to the low lattice thermal conduc-tivity(κ_(lat))less than 0.48 W m^(-1)K^(-1)from 300 to 723 K,at which Pb_(5)Sb_(16)Bi_(2)Se_(32)especially shows the ultralow value of 0.25 W m^(-1)K^(-1).As a result,the thermoelectric figure of merit,ZT~0.34 at 723 K,is obtained for the intrinsic Pb_(5)Sb_(12)Bi_(6)Se_(32).展开更多
Nanosized Ba_(1-x)Bi_(x)Fe_(1-x)Cu_(x)O_(3)(12–50 nm)with x values of 0,0.01,0.05,and 0.1 system was prepared using the Pechini method.Structural,morphological,surface and optical characterizations were performed for...Nanosized Ba_(1-x)Bi_(x)Fe_(1-x)Cu_(x)O_(3)(12–50 nm)with x values of 0,0.01,0.05,and 0.1 system was prepared using the Pechini method.Structural,morphological,surface and optical characterizations were performed for the prepared samples.Cubic phase was the predominant phase for the undoped BaFeO_(3)and Bi and Cu co-doped BaFeO_(3)samples.Minor phases of monoclinic Ba_(2)Fe_(2)O_(5),orthorhombic BaFe_(2)O_(4)and orthorhombic BaCO_(3)were identified for all the prepared samples.Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)sample has the lowest band gap(2.43 e V).98.1%paracetamol removal was achieved with 0.75 g/L of Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)at pH9 after 120 min.The paracetamol degradation follows the pseudo first-order kinetics.HO·is the main oxidative species responsible for the paracetamol degradation.Gas chromatography–mass spectrometry(GC–MS)analysis was performed at the end of the photocatalytic degradation experiment under optimum operating condition using Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)to explain the reaction mechanism and identify the intermediate by-products which is confirmed by ultraviolet/visible(UV/Vis)spectroscopy study at different reaction times.展开更多
Since Bi2Sr2Ca1Cu2O8＋x（Bi2212） wires are subject to mechanical loadings, degradation of critical current will occur. The effect of compressive loadings on the critical current of Bi2212 wire is studied by consideri...Since Bi2Sr2Ca1Cu2O8＋x（Bi2212） wires are subject to mechanical loadings, degradation of critical current will occur. The effect of compressive loadings on the critical current of Bi2212 wire is studied by considering micro-buckling of filament. A Bi2212 wire is regarded as a unidirectional filament-reinforced composite in the theoretical analysis. By considering the influence of inclusion, the micro-buckling wavelength can be derived by using a two-dimensional model. Based on the experimental results, the critical current is fitted as a function of buckling wavelength. It is found that the decrease of the critical current is directly proportional to the reciprocal of square of the buckling wavelength. Change of micro-buckling wavelength with material parameters is discussed. A critical strain in the wire with a filament bridge is analyzed using the finite element method.展开更多
基金Funded by the National Natural Science Foundation of China(No.51465039)Natural Science Foundation of Jiangxi Province(No.20151BAB206041,20161BAB206122)Fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201508)
文摘The effects of different Bi contents on the properties of Sn solders were studied. The interfacial reaction and growth behavior of intermetallic compounds（IMCs） layer（η-Cu6 Sn5 + e-Cu3 Sn） for various soldering time and the influence of Bi addition on the thermal behavior of Sn-x Bi solder alloys were investigated. The Cu6 Sn5 IMC could be observed as long as the molten solder contacted with the Cu substrate. However, with the longer welding time such as 60 and 300 s, the Cu3 Sn IMC was formed at the interface between Cu6 Sn5 and Cu substrate. With the increase of soldering time, the thickness of total IMCs increased, meanwhile, the grain size of Cu6 Sn5 also increased. An appropriate amount of Bi element was beneficial for the growth of total IMCs,but excessive Bi（≥ 5 wt%） inhibited the growth of Cu6 Sn5 and Cu3 Sn IMC in Sn-x Bi/Cu microelectronic interconnects. Furthermore, with the Bi contents increasing（Sn-10 Bi solder in this present investigation）, some Bi particles accumulated at the interface between Cu6 Sn5 layer and the solder.
基金supported in part by the National Natural Science Foundation of China(52102218)the National Key Research and Development Program of China(2020YFA0710303)+2 种基金the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ127)the Minjiang Scholar Professorship(GXRC-21004)the Natural Science Foundation of Fujian Province(2021J01594).
文摘Five new semiconductors Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)(x=0,1,2,3,and 4)have been synthesized for the first time,which adopt pavonite-type structure and crystallize in monoclinic C2/m space group.The crystal structure is composed of two different types of polyhedral slabs.Slab-I is a galena-like structure motif that forms with[MSe_(6)](M=Pb,Sb,and Bi)octahedra and slab-Ⅱcontains one octahedral[MSe_(6)]block and paired squared pyramids[MSe_(5)].Pb_(5)Sb_(12+x)Bi_(6-x)Se_(32)exhibits n-type semiconductor behaviors and the remarkable Seebeck coefficient from-64.1μV K^(-1)for x=0 sample to-242μV K^(-1)forx=4 sample at 300 K.Moreover,the Pb_(5)Sb_(12)Bi_(6)Se_(32)has the highest carrier concentration of 1.35×10^(20)cm^(-3)in pavonite-type materials.The complex compositions,mixed occupancies of the cations,and quasi-two-dimensional structure lead to the low lattice thermal conduc-tivity(κ_(lat))less than 0.48 W m^(-1)K^(-1)from 300 to 723 K,at which Pb_(5)Sb_(16)Bi_(2)Se_(32)especially shows the ultralow value of 0.25 W m^(-1)K^(-1).As a result,the thermoelectric figure of merit,ZT~0.34 at 723 K,is obtained for the intrinsic Pb_(5)Sb_(12)Bi_(6)Se_(32).
文摘Nanosized Ba_(1-x)Bi_(x)Fe_(1-x)Cu_(x)O_(3)(12–50 nm)with x values of 0,0.01,0.05,and 0.1 system was prepared using the Pechini method.Structural,morphological,surface and optical characterizations were performed for the prepared samples.Cubic phase was the predominant phase for the undoped BaFeO_(3)and Bi and Cu co-doped BaFeO_(3)samples.Minor phases of monoclinic Ba_(2)Fe_(2)O_(5),orthorhombic BaFe_(2)O_(4)and orthorhombic BaCO_(3)were identified for all the prepared samples.Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)sample has the lowest band gap(2.43 e V).98.1%paracetamol removal was achieved with 0.75 g/L of Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)at pH9 after 120 min.The paracetamol degradation follows the pseudo first-order kinetics.HO·is the main oxidative species responsible for the paracetamol degradation.Gas chromatography–mass spectrometry(GC–MS)analysis was performed at the end of the photocatalytic degradation experiment under optimum operating condition using Ba_(0.95)Bi_(0.05)Fe_(0.95)Cu_(0.05)O_(3)to explain the reaction mechanism and identify the intermediate by-products which is confirmed by ultraviolet/visible(UV/Vis)spectroscopy study at different reaction times.
基金Project supported by the National Natural Science Foundation of China(Nos.11327802,11472120,and 11421062)the National Key Project of Magneto-Constrained Fusion Energy Development Program(No.2013GB110002)the Fundamental Research Funds for the Central Universities(No.lzujbky-2017-k18)
文摘Since Bi2Sr2Ca1Cu2O8＋x（Bi2212） wires are subject to mechanical loadings, degradation of critical current will occur. The effect of compressive loadings on the critical current of Bi2212 wire is studied by considering micro-buckling of filament. A Bi2212 wire is regarded as a unidirectional filament-reinforced composite in the theoretical analysis. By considering the influence of inclusion, the micro-buckling wavelength can be derived by using a two-dimensional model. Based on the experimental results, the critical current is fitted as a function of buckling wavelength. It is found that the decrease of the critical current is directly proportional to the reciprocal of square of the buckling wavelength. Change of micro-buckling wavelength with material parameters is discussed. A critical strain in the wire with a filament bridge is analyzed using the finite element method.
