Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure.They possess excellent degradation efficiency,stability and reusability.In this work,Fe_(80)Si_(10)B_(1...Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure.They possess excellent degradation efficiency,stability and reusability.In this work,Fe_(80)Si_(10)B_(10) and Fe_(83)Si_(5)B_(8)P_(4) amorphous ribbons exhibited ad-vanced catalytic performance for the degradation of Methyl Blue(MB)and Rhodamine B(RhB)dyes,and the color removal reach nearly 100%within 11 min for both the dyes.Com-pared with the Fe_(80)Si_(10)B_(10) amorphous ribbon,the Fe_(83)Si_(5)B_(8)P_(4) ribbon showed higher degra-dation efficiency due to its lower reaction activation energy,higher electron transfer ability and higher Fe content,and the formation of the galvanic cell between the strong Fe-P bonds and the weak Fe-B bonds.It also exhibited high stability and reusability.The degradation ef-ficiency was improved when the appropriate concentration of H_(2)O_(2) is added.As regards the pH,high degradation efficiency was observed in acidic MB solution,but it decreased as the pH increased up to pH 7.The application of the electro-Fenton-like process is discussed,which can effectively improve the degradation performance in a nearly natural solution.This study presents a high efficiency low-cost catalyst for synthetic dye degradation and expands the functional applications of Fe-based amorphous alloys.展开更多
Tin telluride(SnTe)overwhelmingly continues to be studied owing to its promising thermoelectric properties,tunable electronic structure,and its potential as an alternate to toxic lead telluride(PbTe)based materials.In...Tin telluride(SnTe)overwhelmingly continues to be studied owing to its promising thermoelectric properties,tunable electronic structure,and its potential as an alternate to toxic lead telluride(PbTe)based materials.In this research,we engineer the electronic properties of SnTe by co-doping Mn and Bi below their individual solubility limit.The First principles density functio nal theory studies reveal that both Bi and Mn introduce resonance states,thereby increasing the density of states near the Fermi level leading to enhanced Seebeck coefficient.This unique combination of using two resonant dopants to introduce flatter bands is effective in achieving higher performance at lower tempe ratures manifesting into a large Seebeck value of~91μV/K at room temperature in the present case.Both elements optimally co-doped results in a very high power factor value of~24.3μW/cmK^(2) at 773 K when compared to other high performance SnTe based materials.A zT of~0.93 at 773 K is achieved by tuning the proportion of the co-dopants Mn and Bi in SnTe.The hardness value of pristine SnTe was also seen to increase after doping.As a result,synergistic optimized doping proves to be a suitable means for obtaining thermoelectric materials of superior characteristics without the need for heavy doping.展开更多
Oxide films formed on the surfaces of Fe-based bulk metallic glasses in the temperature range between 373 K and 573 K were characterized and their effects on the corrosion behaviors were investigated by microstructura...Oxide films formed on the surfaces of Fe-based bulk metallic glasses in the temperature range between 373 K and 573 K were characterized and their effects on the corrosion behaviors were investigated by microstructural and electrochemical analysis. The oxide film formed at 573 K is iron-rich oxide and it exhibits an n-type semiconductor at a higher potential than 0.35 V and a p-type semiconductor at a lower potential than 0.35 V. Capacitance measurements show that the donor density decreases with the increase in oxidation temperature, while the thickness of the space charge layer increases with the oxidation temperature rising. The result of immersion tests shows that the mass loss rate increases with the oxidation temperature rising. Therefore, the correlation between microstructure and corrosion resistance needs to be proposed because the corrosion resistance is deteriorated with the development of the oxide films.展开更多
Composites were prepared,through hot pressing,using carbon materials with different pore size distributions as additives for commercial Bi_(0.5)Sb_(1.5)Te_(3) thermoelectric material(BST,p-type).Thermoelectric propert...Composites were prepared,through hot pressing,using carbon materials with different pore size distributions as additives for commercial Bi_(0.5)Sb_(1.5)Te_(3) thermoelectric material(BST,p-type).Thermoelectric properties of the composites were measured in a temperature range of 298-473 K.Thermal conductivity of the composites,especially lattice thermal conductivity,was effectively decreased due to the mesoporous properties of the incorporated carbon additives.The electrical conductivity of the composites slightly decreased due to the electron scattering at the interface between the carbon material and the commercial BST matrix.The composite with 0.2 vol.%mesoporous carbon powder(36%mesoporosity)exhibited a figure of merit value approximately 10.7%higher than that of commercial BST without additives.This behavior resulted in 116%improved output power in the composite block-based single element compared with a bare BST thermoelectric block.The enhanced figure of merit was attributed to the effective reduction of lattice thermal conductivity by acoustic phonons scattering at the interface between the BST matrix and the mesoporous carbon as well as at the pore surfaces within the mesoporous carbon.By utilizing mesoporous carbon materials used in this study,the shortcomings and economic difficulties of the composite process with low dimensional carbon additives(carbon nanotubes,graphene,and nanodiamond)can be overcome for extensive practical applications.Mesoporous carbon powder with a tailored porosity distribution revealed the validity of bulk-type carbon additives to enhance the figure of merit of commercial thermoelectric materials.展开更多
A facile compositional tuning by Sb and Cu addition is performed to generate engineered defects in GeTe alloys with ultra-low thermal conductivity.Substitution of Sb and Cu at the Ge-site enhances the power factor due...A facile compositional tuning by Sb and Cu addition is performed to generate engineered defects in GeTe alloys with ultra-low thermal conductivity.Substitution of Sb and Cu at the Ge-site enhances the power factor due to the optimization of carrier concentration while maintaining the convergence of the valence bands.Furthermore,complex multi-dimensional defect structures including 0D(0-dimensional)substituted Sb_(Ge)and Cu_(Ge),2D twin and inversion boundaries,3D herringbone structures,3D embedded nanostructures,and 3D Cu-rich coherent precipitates are generated,which significantly reduce the lattice thermal conductivity benefitting from a collective phonon scattering.Due to this simultaneous manipulation of electronic and thermal transport properties,a maximum thermoelectric figure of merit(zT)of 1.4 was obtained at 723 K.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea govern-ment(MSIT)(No.2018R1A4A1022260).
文摘Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure.They possess excellent degradation efficiency,stability and reusability.In this work,Fe_(80)Si_(10)B_(10) and Fe_(83)Si_(5)B_(8)P_(4) amorphous ribbons exhibited ad-vanced catalytic performance for the degradation of Methyl Blue(MB)and Rhodamine B(RhB)dyes,and the color removal reach nearly 100%within 11 min for both the dyes.Com-pared with the Fe_(80)Si_(10)B_(10) amorphous ribbon,the Fe_(83)Si_(5)B_(8)P_(4) ribbon showed higher degra-dation efficiency due to its lower reaction activation energy,higher electron transfer ability and higher Fe content,and the formation of the galvanic cell between the strong Fe-P bonds and the weak Fe-B bonds.It also exhibited high stability and reusability.The degradation ef-ficiency was improved when the appropriate concentration of H_(2)O_(2) is added.As regards the pH,high degradation efficiency was observed in acidic MB solution,but it decreased as the pH increased up to pH 7.The application of the electro-Fenton-like process is discussed,which can effectively improve the degradation performance in a nearly natural solution.This study presents a high efficiency low-cost catalyst for synthetic dye degradation and expands the functional applications of Fe-based amorphous alloys.
基金supported by grants from the National Research Foundation(NRF)of Korea(No.2018R1A41A1022260),funded by the Korean government(MSIT)the grant in the form of DST INSPIRE Faculty award from Department of Science and Technology,Government of India。
文摘Tin telluride(SnTe)overwhelmingly continues to be studied owing to its promising thermoelectric properties,tunable electronic structure,and its potential as an alternate to toxic lead telluride(PbTe)based materials.In this research,we engineer the electronic properties of SnTe by co-doping Mn and Bi below their individual solubility limit.The First principles density functio nal theory studies reveal that both Bi and Mn introduce resonance states,thereby increasing the density of states near the Fermi level leading to enhanced Seebeck coefficient.This unique combination of using two resonant dopants to introduce flatter bands is effective in achieving higher performance at lower tempe ratures manifesting into a large Seebeck value of~91μV/K at room temperature in the present case.Both elements optimally co-doped results in a very high power factor value of~24.3μW/cmK^(2) at 773 K when compared to other high performance SnTe based materials.A zT of~0.93 at 773 K is achieved by tuning the proportion of the co-dopants Mn and Bi in SnTe.The hardness value of pristine SnTe was also seen to increase after doping.As a result,synergistic optimized doping proves to be a suitable means for obtaining thermoelectric materials of superior characteristics without the need for heavy doping.
基金supported by the National Natural Science Foundation of China (No.51165038)the Doctoral Startup Fund of Nanchang Hangkong University (No.EA201103238)the Korean Ministry of Commerce, Industry and Energy through the project entitled as "The Development of Structural Metallic Materials and Parts with Super Strength and High Performance"
文摘Oxide films formed on the surfaces of Fe-based bulk metallic glasses in the temperature range between 373 K and 573 K were characterized and their effects on the corrosion behaviors were investigated by microstructural and electrochemical analysis. The oxide film formed at 573 K is iron-rich oxide and it exhibits an n-type semiconductor at a higher potential than 0.35 V and a p-type semiconductor at a lower potential than 0.35 V. Capacitance measurements show that the donor density decreases with the increase in oxidation temperature, while the thickness of the space charge layer increases with the oxidation temperature rising. The result of immersion tests shows that the mass loss rate increases with the oxidation temperature rising. Therefore, the correlation between microstructure and corrosion resistance needs to be proposed because the corrosion resistance is deteriorated with the development of the oxide films.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2018R1A4A1022260)。
文摘Composites were prepared,through hot pressing,using carbon materials with different pore size distributions as additives for commercial Bi_(0.5)Sb_(1.5)Te_(3) thermoelectric material(BST,p-type).Thermoelectric properties of the composites were measured in a temperature range of 298-473 K.Thermal conductivity of the composites,especially lattice thermal conductivity,was effectively decreased due to the mesoporous properties of the incorporated carbon additives.The electrical conductivity of the composites slightly decreased due to the electron scattering at the interface between the carbon material and the commercial BST matrix.The composite with 0.2 vol.%mesoporous carbon powder(36%mesoporosity)exhibited a figure of merit value approximately 10.7%higher than that of commercial BST without additives.This behavior resulted in 116%improved output power in the composite block-based single element compared with a bare BST thermoelectric block.The enhanced figure of merit was attributed to the effective reduction of lattice thermal conductivity by acoustic phonons scattering at the interface between the BST matrix and the mesoporous carbon as well as at the pore surfaces within the mesoporous carbon.By utilizing mesoporous carbon materials used in this study,the shortcomings and economic difficulties of the composite process with low dimensional carbon additives(carbon nanotubes,graphene,and nanodiamond)can be overcome for extensive practical applications.Mesoporous carbon powder with a tailored porosity distribution revealed the validity of bulk-type carbon additives to enhance the figure of merit of commercial thermoelectric materials.
基金supported by grants from the National Research Foundation(NRF)of Korea(No.2021R1A4A2001658)funded by the Korean government(MSIT).
文摘A facile compositional tuning by Sb and Cu addition is performed to generate engineered defects in GeTe alloys with ultra-low thermal conductivity.Substitution of Sb and Cu at the Ge-site enhances the power factor due to the optimization of carrier concentration while maintaining the convergence of the valence bands.Furthermore,complex multi-dimensional defect structures including 0D(0-dimensional)substituted Sb_(Ge)and Cu_(Ge),2D twin and inversion boundaries,3D herringbone structures,3D embedded nanostructures,and 3D Cu-rich coherent precipitates are generated,which significantly reduce the lattice thermal conductivity benefitting from a collective phonon scattering.Due to this simultaneous manipulation of electronic and thermal transport properties,a maximum thermoelectric figure of merit(zT)of 1.4 was obtained at 723 K.
