Fe–S compounds with hexagonal crystal structure are potential hydrogen permeation barrier during H2S corrosion. Hexagonal system Fe–S films were prepared on carbon steel through corrosion and CVD deposition, and the...Fe–S compounds with hexagonal crystal structure are potential hydrogen permeation barrier during H2S corrosion. Hexagonal system Fe–S films were prepared on carbon steel through corrosion and CVD deposition, and the barrier effect of different Fe–S films on hydrogen permeation was tested using electrochemical hydrogen permeation method. After that, the electrical properties of Fe–S compound during phase transformation were measured using thermoelectric measurement system. Results show that the mackinawite has no obvious barrier effect on hydrogen penetration, as a p-type semiconductor, and pyrrhotite (including troilite) has obvious barrier effect on hydrogen penetration,as an n-type semiconductor. Hydrogen permeation tests showed peak permeation performance when the surface was deposited with a continuous film of pyrrhotite (Fe_(1–x)S) and troilite. The FeS compounds suppressed hydrogen permeation by the promotion of the hydrogen evolution reaction, semiconducting inversion from p-to n-type, and the migration of ions at the interface.展开更多
Cu_(3)SbSe_(4),a copper-based sulfide free of rare earth elements,has received extensive attention in ther-moelectric materials.However,its low carrier concentration restricts its widespread application.In this study,...Cu_(3)SbSe_(4),a copper-based sulfide free of rare earth elements,has received extensive attention in ther-moelectric materials.However,its low carrier concentration restricts its widespread application.In this study,a microwave-assisted solution synthesis method was used to produce samples of Cu_(3)SbSe_(4),which enabled the formation of CuSe in situ and increased the yield.Through the use of first-principles cal-culations,structural analysis,and performance evaluation,it was found that CuSe can enhance the carrier concentration and that induced nano-defects have a positive effect on reducing the lattice thermal conductivity.Moreover,doping with Sn decreases the band gap of the system and moves the Fermi level into the valence band,increasing the carrier concentration to 1.15×10^(-20)cm^(-3).Finally,the zT value of the Cu_(3)Sb_(0.98)Sn_(0.02)Se_(4)sample was achieved at 1.05 at 623 K when the theoretical yield of a single synthesis was 10 mmol.展开更多
The previous works commonly adjust the carrier concentration through acceptor doping,but at the same time,the decrease of the Seebeck coefficient limits the further improvement of electrical properties in Cu_(3)SbSe_(...The previous works commonly adjust the carrier concentration through acceptor doping,but at the same time,the decrease of the Seebeck coefficient limits the further improvement of electrical properties in Cu_(3)SbSe_(4)-based materials.In this work,a microwave-assisted hydrothermal synthesis method was used to synthesize Cu_(3)SbSe_(4)/TiO_(2) hollow microspheres.Part of TiO_(2) participates in the reaction,replaces the Sb site of Cu_(3)SbSe_(4) to form holes,and the rest is dispersed in the matrix in the form of the second phase.The first-principles calculations reveal that the doping of Ti significantly changes the band structure and phonon spectrum,thereby regulating carrier concentration while increasing phonon scattering.In addition,experimental results show that the energy filtering effect generated by the extra-mixed TiO_(2) nano particles,which suppresses the decrease of Seebeck coefficient by acceptor doping.Consequently,the highest average power factor 897.5 mW m^(-1) K^(-2) and the zT peak value of 0.70 can be obtained in Cu_(3)SbSe_(4)/6%TiO_(2) sample at 298e623 K.This work provides a new sight to improve the thermoelectric properties in Cu_(3)SbSe_(4) through carrier concentration regulation and nano-phase composition.展开更多
As an eco-friendly thermoelectric material,Sn Te has attracted extensive attention.In this study,we use a stepwise strategy to enhance the thermoelectric performance of Sn Te.Firstly,Ag Cl is doped into Sn Te to reali...As an eco-friendly thermoelectric material,Sn Te has attracted extensive attention.In this study,we use a stepwise strategy to enhance the thermoelectric performance of Sn Te.Firstly,Ag Cl is doped into Sn Te to realize band convergence and enlarge the band gap of Ag Cl-doped Sn Te.Ag Cl-doping also induces dense point defects,strengthens the phonon scattering,and reduces the lattice thermal conductivity.Secondly,Sb is alloyed into Ag Cl-doped Sn Te to further optimize the carrier concentration and simultaneously reduce the lattice thermal conductivity,leading to improved thermoelectric dimensionless figure of merit,ZT.Finally,(Sn_(0.81)Sb_(0.19)Te)_(0.93)(Ag Cl)_(0.07)has approached the ZT value as high as~0.87 at 773 K,which is 272%higher than that of pristine Sn Te.This study indicates that stepwise Ag Cl-doping and Sb-alloying can significantly improve thermoelectric performance of Sn Te due to synergistic band engineering,carrier concentration optimization and defect engineering.展开更多
The ternary chalcopyrite CuGaTe_(2)has emerged as a promising p-type thermoelectric material with its advantages of low cost,good stability,and non-toxic elements.However,its thermoelectric performance is limited by t...The ternary chalcopyrite CuGaTe_(2)has emerged as a promising p-type thermoelectric material with its advantages of low cost,good stability,and non-toxic elements.However,its thermoelectric performance is limited by the intrinsic low electrical conductivity and high lattice thermal conductivity.In this work,A deficiency of Cu in Cu_(1–x)Ga Te_(2)semiconductors can be used to optimize the electrical properties by improving the carrier concentration and to reduce thermal conductivity through multi-scale phonon scattering,which is predicted and guided by the First-principles density functional theory calculations.The carrier concentration is increased to 1020,which compensates for the low electrical performance caused by the intrinsic low nHof CuGaTe_(2).The average power factor of Cu_(0.96)Ga Te_(2)reaches 106.3%higher than that of the original CuGaTe_(2).In addition,the lattice thermal conductivity of the defective samples is greatly reduced at high temperatures,which is mainly due to the reduction of sound speed and phonon scattering.All the above factors contribute to the highest dimensionless figure of merit(ZT)value of 1.23 at 823 K in Cu_(0.96)GaTe_(2),which is 114%higher than the pristine CuGaTe_(2),and the average ZT is 171.4%higher.展开更多
Alloying with Se is proved to be feasible to suppress the lattice thermal conductivity(κL)of tellurium by introducing multidimensional lattice defects.However,extra ionization impurity centers induced by Se alloying ...Alloying with Se is proved to be feasible to suppress the lattice thermal conductivity(κL)of tellurium by introducing multidimensional lattice defects.However,extra ionization impurity centers induced by Se alloying are harmful to the electric transport properties of the matrix.In this paper,we propose that the incorporation of Ag could successfully compensate the lost carrier mobility(μH)due to Se alloying through the regulation of microstructure,resulting in the higher power factor(PF)than that of samples without Ag.After composition optimization,theκLdecreased from 1.29 W m^(-1)K^(-1) of Te_(0.99)Sb_(0.01) to 1.05 W m^(-1)K^(-1) of Te_(0.94)Ag_(0.02)Se_(0.03)Sb_(0.01) at 350 K,while the PF remained unchanged or even slightly increased.Benefit from the synergistic effect of carrier mobility compensation and phonon scattering,a maximum z T of 0.91 at 573 K and an average z T of 0.57(between 298 and 573 K)are achieved in Te_(0.94)Ag_(0.02)Se_(0.03)Sb_(0.01).This work presents a new strategy for decoupling the thermal and electric parameters of Te-based thermoelectric materials.展开更多
Mg-based thermoelectric materials have attracted more and more attention because of their rich composition elements,green environmental protection,and lower price.In recent years,the thermoelectric properties of n-typ...Mg-based thermoelectric materials have attracted more and more attention because of their rich composition elements,green environmental protection,and lower price.In recent years,the thermoelectric properties of n-type Mg_(3)Sb_(2) materials have been optimized by doping chalcogenide elements(S,Se,and Te)at the anionic position.In this work,n-type Mg_(3.2)A_(x)Sb_(1.5)Bi_(0.5)(A=Gd,Ho;x=0.01,0.02,0.03,and 0.4)samples were prepared by the cation site doping of lanthanide elements(Gd and Ho).The research results show that Gd and Ho doped n-type Mg3.2Sb1.5Bi0.5samples are entirely comparable to the S,Se,and Te doped n-type Mg3.2Sb1.5Bi0.5samples,demonstrating more excellent thermoelectric properties.Doping with lanthanides(Gd and Ho)at the Mg site increases the carrier concentration of the material to 8.161×10^(19)cm^(-3).Doping induces the contribution of more electron,thus obtaining higher conductivity.The maximum zT value of the Mg_(3.2)Gd_(0.02)Sb_(1.5)Bi_(0.5) and the Mg_(3.2)Ho_(0.02)Sb_(1.5)Bi_(0.5) samples reaches 1.61 and 1.55,respectively.This work theoretically and experimentally demonstrates Gd and Ho are efficient n-type dopants for Mg_(3.2)Sb_(1.5)Bi_(0.5) thermoelectric material.展开更多
基金financailly supported by the National Natural Science Foundation of China (Nos.52275198 and 51805292)the Beijing Natural Science Foundation,China(No.2202020)the Tribology Science Fund of State Key Laboratory of Tribology,China (No.SKLT2022B11)。
文摘Fe–S compounds with hexagonal crystal structure are potential hydrogen permeation barrier during H2S corrosion. Hexagonal system Fe–S films were prepared on carbon steel through corrosion and CVD deposition, and the barrier effect of different Fe–S films on hydrogen permeation was tested using electrochemical hydrogen permeation method. After that, the electrical properties of Fe–S compound during phase transformation were measured using thermoelectric measurement system. Results show that the mackinawite has no obvious barrier effect on hydrogen penetration, as a p-type semiconductor, and pyrrhotite (including troilite) has obvious barrier effect on hydrogen penetration,as an n-type semiconductor. Hydrogen permeation tests showed peak permeation performance when the surface was deposited with a continuous film of pyrrhotite (Fe_(1–x)S) and troilite. The FeS compounds suppressed hydrogen permeation by the promotion of the hydrogen evolution reaction, semiconducting inversion from p-to n-type, and the migration of ions at the interface.
基金supported by the National Natural Science Foundation of China(No.51871240).
文摘Cu_(3)SbSe_(4),a copper-based sulfide free of rare earth elements,has received extensive attention in ther-moelectric materials.However,its low carrier concentration restricts its widespread application.In this study,a microwave-assisted solution synthesis method was used to produce samples of Cu_(3)SbSe_(4),which enabled the formation of CuSe in situ and increased the yield.Through the use of first-principles cal-culations,structural analysis,and performance evaluation,it was found that CuSe can enhance the carrier concentration and that induced nano-defects have a positive effect on reducing the lattice thermal conductivity.Moreover,doping with Sn decreases the band gap of the system and moves the Fermi level into the valence band,increasing the carrier concentration to 1.15×10^(-20)cm^(-3).Finally,the zT value of the Cu_(3)Sb_(0.98)Sn_(0.02)Se_(4)sample was achieved at 1.05 at 623 K when the theoretical yield of a single synthesis was 10 mmol.
基金This work was financially supported by the National Natural Science Foundation of China(No.51871240).The calculations were carried out at the National Supercomputing Center in Shenzhen(Shenzhen Cloud Computing Center).
文摘The previous works commonly adjust the carrier concentration through acceptor doping,but at the same time,the decrease of the Seebeck coefficient limits the further improvement of electrical properties in Cu_(3)SbSe_(4)-based materials.In this work,a microwave-assisted hydrothermal synthesis method was used to synthesize Cu_(3)SbSe_(4)/TiO_(2) hollow microspheres.Part of TiO_(2) participates in the reaction,replaces the Sb site of Cu_(3)SbSe_(4) to form holes,and the rest is dispersed in the matrix in the form of the second phase.The first-principles calculations reveal that the doping of Ti significantly changes the band structure and phonon spectrum,thereby regulating carrier concentration while increasing phonon scattering.In addition,experimental results show that the energy filtering effect generated by the extra-mixed TiO_(2) nano particles,which suppresses the decrease of Seebeck coefficient by acceptor doping.Consequently,the highest average power factor 897.5 mW m^(-1) K^(-2) and the zT peak value of 0.70 can be obtained in Cu_(3)SbSe_(4)/6%TiO_(2) sample at 298e623 K.This work provides a new sight to improve the thermoelectric properties in Cu_(3)SbSe_(4) through carrier concentration regulation and nano-phase composition.
基金financially supported by the National Natural Science Foundation of China(No.51871240)。
文摘As an eco-friendly thermoelectric material,Sn Te has attracted extensive attention.In this study,we use a stepwise strategy to enhance the thermoelectric performance of Sn Te.Firstly,Ag Cl is doped into Sn Te to realize band convergence and enlarge the band gap of Ag Cl-doped Sn Te.Ag Cl-doping also induces dense point defects,strengthens the phonon scattering,and reduces the lattice thermal conductivity.Secondly,Sb is alloyed into Ag Cl-doped Sn Te to further optimize the carrier concentration and simultaneously reduce the lattice thermal conductivity,leading to improved thermoelectric dimensionless figure of merit,ZT.Finally,(Sn_(0.81)Sb_(0.19)Te)_(0.93)(Ag Cl)_(0.07)has approached the ZT value as high as~0.87 at 773 K,which is 272%higher than that of pristine Sn Te.This study indicates that stepwise Ag Cl-doping and Sb-alloying can significantly improve thermoelectric performance of Sn Te due to synergistic band engineering,carrier concentration optimization and defect engineering.
基金financially supported by the National Natural Science Foundation of China(No.51871240)supported by the National Supercomputing Center in Shenzhen(Shenzhen Cloud Computing Center)。
文摘The ternary chalcopyrite CuGaTe_(2)has emerged as a promising p-type thermoelectric material with its advantages of low cost,good stability,and non-toxic elements.However,its thermoelectric performance is limited by the intrinsic low electrical conductivity and high lattice thermal conductivity.In this work,A deficiency of Cu in Cu_(1–x)Ga Te_(2)semiconductors can be used to optimize the electrical properties by improving the carrier concentration and to reduce thermal conductivity through multi-scale phonon scattering,which is predicted and guided by the First-principles density functional theory calculations.The carrier concentration is increased to 1020,which compensates for the low electrical performance caused by the intrinsic low nHof CuGaTe_(2).The average power factor of Cu_(0.96)Ga Te_(2)reaches 106.3%higher than that of the original CuGaTe_(2).In addition,the lattice thermal conductivity of the defective samples is greatly reduced at high temperatures,which is mainly due to the reduction of sound speed and phonon scattering.All the above factors contribute to the highest dimensionless figure of merit(ZT)value of 1.23 at 823 K in Cu_(0.96)GaTe_(2),which is 114%higher than the pristine CuGaTe_(2),and the average ZT is 171.4%higher.
基金financially supported by the National Natural Science Foundation of China (No. 51871240)。
文摘Alloying with Se is proved to be feasible to suppress the lattice thermal conductivity(κL)of tellurium by introducing multidimensional lattice defects.However,extra ionization impurity centers induced by Se alloying are harmful to the electric transport properties of the matrix.In this paper,we propose that the incorporation of Ag could successfully compensate the lost carrier mobility(μH)due to Se alloying through the regulation of microstructure,resulting in the higher power factor(PF)than that of samples without Ag.After composition optimization,theκLdecreased from 1.29 W m^(-1)K^(-1) of Te_(0.99)Sb_(0.01) to 1.05 W m^(-1)K^(-1) of Te_(0.94)Ag_(0.02)Se_(0.03)Sb_(0.01) at 350 K,while the PF remained unchanged or even slightly increased.Benefit from the synergistic effect of carrier mobility compensation and phonon scattering,a maximum z T of 0.91 at 573 K and an average z T of 0.57(between 298 and 573 K)are achieved in Te_(0.94)Ag_(0.02)Se_(0.03)Sb_(0.01).This work presents a new strategy for decoupling the thermal and electric parameters of Te-based thermoelectric materials.
基金the National Natural Science Foundation of China(No.51871240)。
文摘Mg-based thermoelectric materials have attracted more and more attention because of their rich composition elements,green environmental protection,and lower price.In recent years,the thermoelectric properties of n-type Mg_(3)Sb_(2) materials have been optimized by doping chalcogenide elements(S,Se,and Te)at the anionic position.In this work,n-type Mg_(3.2)A_(x)Sb_(1.5)Bi_(0.5)(A=Gd,Ho;x=0.01,0.02,0.03,and 0.4)samples were prepared by the cation site doping of lanthanide elements(Gd and Ho).The research results show that Gd and Ho doped n-type Mg3.2Sb1.5Bi0.5samples are entirely comparable to the S,Se,and Te doped n-type Mg3.2Sb1.5Bi0.5samples,demonstrating more excellent thermoelectric properties.Doping with lanthanides(Gd and Ho)at the Mg site increases the carrier concentration of the material to 8.161×10^(19)cm^(-3).Doping induces the contribution of more electron,thus obtaining higher conductivity.The maximum zT value of the Mg_(3.2)Gd_(0.02)Sb_(1.5)Bi_(0.5) and the Mg_(3.2)Ho_(0.02)Sb_(1.5)Bi_(0.5) samples reaches 1.61 and 1.55,respectively.This work theoretically and experimentally demonstrates Gd and Ho are efficient n-type dopants for Mg_(3.2)Sb_(1.5)Bi_(0.5) thermoelectric material.
