The photoluminescence of Dy^(3+) doped and Dy^(3+), Ce^(3+) codoped in Ba_3La(BO_3)_3 were studied. The dependence of the charge-to-radius ratio (z/r) for RE^(3+)(RE=La, Ce), the Ce^(3+), Dy^(3+) content on the emissi...The photoluminescence of Dy^(3+) doped and Dy^(3+), Ce^(3+) codoped in Ba_3La(BO_3)_3 were studied. The dependence of the charge-to-radius ratio (z/r) for RE^(3+)(RE=La, Ce), the Ce^(3+), Dy^(3+) content on the emission intensity and the yellow to blue intensity ratio (Y/B) of Dy^(3+) were investigated too. The results obtained indicate that Ce^(3+) can sensitize the luminescence of Dy^(3+). The optimum concentration of Dy^(3+) in Ba_3La(BO_3)_3 is x_(Dy)=0.06. According to the dependence of the concentration of Dy^(3+) in Ba_3La(BO_3)_3 under the excitation of 350 nm, it is confirmed that the mechanism of concentration selfquenching of Dy^(3+) () (()~4F_(9/2)→()~6H_(15/2),) (()~6H_(13/2)) transition is electric dipole-quadrupole interaction.展开更多
A bifunctional electroactive filter was rationally fabricated for simultaneous oxidation and sequestration of toxic trivalent arsentic As(Ⅲ).A novel nanoscale La(OH)_(3) modified electrochemical carbon nanotube(CNT)n...A bifunctional electroactive filter was rationally fabricated for simultaneous oxidation and sequestration of toxic trivalent arsentic As(Ⅲ).A novel nanoscale La(OH)_(3) modified electrochemical carbon nanotube(CNT)network filter was prepared by a facile electrodeposition strategy.The As(Ⅲ)decontamination kinetics and adsorption capacity were both found to increase with the flow rate(1.5-6.0 mL/min)and the applied voltage(0-2.5 V).The CNT filter hybridized with La(OH)_(3)(CNT-La(OH)_(3))has demonstrated the ultra-high adsorption capacity of 750.2 mg/g for As(Ⅲ),which is ascribed to the combined role of sufficient adsorption sites,flow-through filtration and electric field.XPS analysis revealed that the As(Ⅲ)decontamination mechanism involved a two-step adsorption-oxidation process.The formation of inner-sphere La-O-As complexes,ligand exchange and electro-adsorption are all parts of the As(Ⅲ)adsorption process.The adsorbed neutrally-charged As(Ⅲ)was further oxidized to negatively-charged As(V)when aided by an electric field,which could be effectively sequestrated by La(OH)_(3).The CNT-La(OH)_(3) filter shows high stability under alkaline conditions and can be regenerated with dilute NaOH solution.In this study,all experiment results have demonstrated a promising and effective CNT-La(OH)_(3) electrochemical filter for As(Ⅲ)pollution minimization.展开更多
Cationic hydrogels have received great attention to control eutrophication and recycle phosphate.In this study,a type of La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel(La(OH)_(3)@MMCH)was developed as a pot...Cationic hydrogels have received great attention to control eutrophication and recycle phosphate.In this study,a type of La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel(La(OH)_(3)@MMCH)was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment.La(OH)_(3)@MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g,and reached equilibrium within 2 hr.La(OH)_(3)@MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions(including SO_(4)^(2-),Cl^(-),NO_(3)^(-),HCO_(3)^(-),SiO_(4)^(4-) and HA).The adsorption-desorption experiment indicated that La(OH)_(3)@MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent,and 73.3%adsorption capacity remained after five cycles.Moreover,La(OH)_(3)@MMCH was employed to treat surface water with phosphate concentration of 1.90 mg/L and showed great removal efficiency of 95.21%.Actually,MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57%within 24 h,indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate phosphate.Furthermore,the bifunctional structure of La(OH)_(3)@MMCH enabled it to capture phosphate through electrostatic attraction and ligand exchange.All the results prove that La(OH)_(3)@MMCH is a promising adsorbent for eutrophication control and phosphate recovery.展开更多
In this work,tunable white up-conversion luminescence was achieved in the Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) codoped Na_(3)La(VO_(4))_(2) phosphors under 980 nm excitation.The emissions of three primary colors are mainly...In this work,tunable white up-conversion luminescence was achieved in the Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) codoped Na_(3)La(VO_(4))_(2) phosphors under 980 nm excitation.The emissions of three primary colors are mainly attributed to the ~2H_(11/2)/~4S_(3/2)→~4I_(15/2) transitions of Er^(3+),~1G_(4)→~3H_6 transition of Tm^(3+),and_5F_5→~5I_8 transition of Ho^(3+).White luminescence characteristics and mechanisms of up-conversion system were investigated in detail.In addition,the temperature sensing behaviors of multiple levels emission combinations for Na_(3)La(VO_(4))_(2):Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) were analyzed by employing thermally coupled and non-thermally coupled energy levels.Based on the emissions of ~3F_(2,3)/~1G_(4) energy levels,the maximum relative and absolute sensitivities were obtained to be 2.20%/K and 0.279 K^(-1).The design of up-conversion luminescence materials with high-quality white luminescence and excellent sensitivity performance is critical in the field of optical applications.展开更多
Eu^(2+)/Sm^(3+)co-doped dual-emitting Sr_(4)La(PO_(4))_(3)O phosphors were synthesized through a convenient high temperature solid state reaction in reductive atmosphere.The structure,luminescence,energy transfer and ...Eu^(2+)/Sm^(3+)co-doped dual-emitting Sr_(4)La(PO_(4))_(3)O phosphors were synthesized through a convenient high temperature solid state reaction in reductive atmosphere.The structure,luminescence,energy transfer and temperature-dependent luminescence properties of Eu^(2+)/Sm^(3+)co-doped Sr_(4)La(PO_(4))_(3)O phosphors were researched and analyzed in detail.The blue emission of Eu^(2+)and the red emission of Sm^(3+)can work together as FIR signals.Based on the different response characteristics of these two ion emissions to temperature,Sr_(4)La(PO_(4))_(3)O:Eu^(2+)/Sm^(^(3+))phosphor achieves the relative sensitivity of0.48384%/K and a wide range of temperature measurements from room temperature to 573 K.The results reveal that the Sr_(4)La(PO_(4))_(3)O:Eu^(2+)/Sm^(3+)phosphor has application prospect in the field of high temperature optical thermometry.The energy transfer mechanism is proved to be the dipole-dipole interaction between Eu^(2+)and Sm^(3+)ions.展开更多
The heat capacities of La(NCS)_3. 7H_2O and Ce(NCS)_3. 7H_2O have been measured from 13 to 300K with a fully-automated adiabatic calorimeter. The construction and procedures of the calorimetric system are described in...The heat capacities of La(NCS)_3. 7H_2O and Ce(NCS)_3. 7H_2O have been measured from 13 to 300K with a fully-automated adiabatic calorimeter. The construction and procedures of the calorimetric system are described in detail. No obvious thermal anomaly was observed for both compounds in the experimental temperature range. The polynomial equations for calculating the heat capacity values of the two compounds in the range 13—300K were obtained by the least-squares fitting based on the experimental C_p data. The C_p values below 13K were estimated by using the Debye and Einstein heat Capacity functions. The standard molar thermodynamic functions were calculated from 0 to 300K. Gibbs energies of formation were also calculated.展开更多
Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous...Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.展开更多
Lithium-rich manganese-based material shows great potential as the high specific cathode materials due to its low cost,environmental friendliness,high operating voltage and simple preparation process.However,the poor ...Lithium-rich manganese-based material shows great potential as the high specific cathode materials due to its low cost,environmental friendliness,high operating voltage and simple preparation process.However,the poor capacity retention and cycling performance caused by its unstable structure during cycling restrict the commercialization.In this work,Li_(1.2)Ni_(0.16)Mn_(0.56)Co_(0.08)O_(2)was synthesized utilizing a Coprecipitation method and different amount of La(PO_(3))_(3)(La(PO_(3))_(3)=2 wt%,4 wt%and 6 wt%)was selected as the coating layer to resolve the above issues.During the calcination process,La(PO_(3))_(3)reacts with impurities such as Li OH and Li_(2)CO_(3)on the lithium-rich surface to reduce the residual lithium on the surface,thus improving the interfacial stability,slowing down the corrosion of the electrolyte,and finally enhancing its electrochemical performance.The cathode materials coated with 4%of La(PO_(3))_(3)showed the best electrochemical performance in terms of capacity retention and cycling performance compared to the pristine NCM.The high initial discharge capacity of 214.21 m Ah/g and capacity retention of 94.2%after 100 cycles at 0.1 C can be obtained.This work provides an effective strategy to protect the cathode from corrosion and will promote its further practical applications in high specific Li-ion batteries.展开更多
文摘The photoluminescence of Dy^(3+) doped and Dy^(3+), Ce^(3+) codoped in Ba_3La(BO_3)_3 were studied. The dependence of the charge-to-radius ratio (z/r) for RE^(3+)(RE=La, Ce), the Ce^(3+), Dy^(3+) content on the emission intensity and the yellow to blue intensity ratio (Y/B) of Dy^(3+) were investigated too. The results obtained indicate that Ce^(3+) can sensitize the luminescence of Dy^(3+). The optimum concentration of Dy^(3+) in Ba_3La(BO_3)_3 is x_(Dy)=0.06. According to the dependence of the concentration of Dy^(3+) in Ba_3La(BO_3)_3 under the excitation of 350 nm, it is confirmed that the mechanism of concentration selfquenching of Dy^(3+) () (()~4F_(9/2)→()~6H_(15/2),) (()~6H_(13/2)) transition is electric dipole-quadrupole interaction.
基金Shanghai Sailing Program,China(No.20YF1400100)Fundamental Research Funds for the Central Universities,China(No.2232020D-54)。
文摘A bifunctional electroactive filter was rationally fabricated for simultaneous oxidation and sequestration of toxic trivalent arsentic As(Ⅲ).A novel nanoscale La(OH)_(3) modified electrochemical carbon nanotube(CNT)network filter was prepared by a facile electrodeposition strategy.The As(Ⅲ)decontamination kinetics and adsorption capacity were both found to increase with the flow rate(1.5-6.0 mL/min)and the applied voltage(0-2.5 V).The CNT filter hybridized with La(OH)_(3)(CNT-La(OH)_(3))has demonstrated the ultra-high adsorption capacity of 750.2 mg/g for As(Ⅲ),which is ascribed to the combined role of sufficient adsorption sites,flow-through filtration and electric field.XPS analysis revealed that the As(Ⅲ)decontamination mechanism involved a two-step adsorption-oxidation process.The formation of inner-sphere La-O-As complexes,ligand exchange and electro-adsorption are all parts of the As(Ⅲ)adsorption process.The adsorbed neutrally-charged As(Ⅲ)was further oxidized to negatively-charged As(V)when aided by an electric field,which could be effectively sequestrated by La(OH)_(3).The CNT-La(OH)_(3) filter shows high stability under alkaline conditions and can be regenerated with dilute NaOH solution.In this study,all experiment results have demonstrated a promising and effective CNT-La(OH)_(3) electrochemical filter for As(Ⅲ)pollution minimization.
基金This work was supported by the Beijing Municipal Science and Technology Project(No.Z181100005518007)the National Key Research and Development Program of China(No.2017YFC0505303)the National Natural Science Foundation of China(Nos.51978054 and 51678053).
文摘Cationic hydrogels have received great attention to control eutrophication and recycle phosphate.In this study,a type of La(OH)_(3) loaded magnetic MAPTAC-based cationic hydrogel(La(OH)_(3)@MMCH)was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment.La(OH)_(3)@MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g,and reached equilibrium within 2 hr.La(OH)_(3)@MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions(including SO_(4)^(2-),Cl^(-),NO_(3)^(-),HCO_(3)^(-),SiO_(4)^(4-) and HA).The adsorption-desorption experiment indicated that La(OH)_(3)@MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent,and 73.3%adsorption capacity remained after five cycles.Moreover,La(OH)_(3)@MMCH was employed to treat surface water with phosphate concentration of 1.90 mg/L and showed great removal efficiency of 95.21%.Actually,MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57%within 24 h,indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate phosphate.Furthermore,the bifunctional structure of La(OH)_(3)@MMCH enabled it to capture phosphate through electrostatic attraction and ligand exchange.All the results prove that La(OH)_(3)@MMCH is a promising adsorbent for eutrophication control and phosphate recovery.
基金Project supported by the National Natural Science Foundation of China (11904046,11974069,11504039)。
文摘In this work,tunable white up-conversion luminescence was achieved in the Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) codoped Na_(3)La(VO_(4))_(2) phosphors under 980 nm excitation.The emissions of three primary colors are mainly attributed to the ~2H_(11/2)/~4S_(3/2)→~4I_(15/2) transitions of Er^(3+),~1G_(4)→~3H_6 transition of Tm^(3+),and_5F_5→~5I_8 transition of Ho^(3+).White luminescence characteristics and mechanisms of up-conversion system were investigated in detail.In addition,the temperature sensing behaviors of multiple levels emission combinations for Na_(3)La(VO_(4))_(2):Yb^(3+),Er^(3+),Tm^(3+),Ho^(3+) were analyzed by employing thermally coupled and non-thermally coupled energy levels.Based on the emissions of ~3F_(2,3)/~1G_(4) energy levels,the maximum relative and absolute sensitivities were obtained to be 2.20%/K and 0.279 K^(-1).The design of up-conversion luminescence materials with high-quality white luminescence and excellent sensitivity performance is critical in the field of optical applications.
基金Project supported by Natural Science Foundation of Zhejiang Province,China(LY19E020005)Science and Technology Innovation Platform and Talent Plan of Zhejiang(2017R52037)。
文摘Eu^(2+)/Sm^(3+)co-doped dual-emitting Sr_(4)La(PO_(4))_(3)O phosphors were synthesized through a convenient high temperature solid state reaction in reductive atmosphere.The structure,luminescence,energy transfer and temperature-dependent luminescence properties of Eu^(2+)/Sm^(3+)co-doped Sr_(4)La(PO_(4))_(3)O phosphors were researched and analyzed in detail.The blue emission of Eu^(2+)and the red emission of Sm^(3+)can work together as FIR signals.Based on the different response characteristics of these two ion emissions to temperature,Sr_(4)La(PO_(4))_(3)O:Eu^(2+)/Sm^(^(3+))phosphor achieves the relative sensitivity of0.48384%/K and a wide range of temperature measurements from room temperature to 573 K.The results reveal that the Sr_(4)La(PO_(4))_(3)O:Eu^(2+)/Sm^(3+)phosphor has application prospect in the field of high temperature optical thermometry.The energy transfer mechanism is proved to be the dipole-dipole interaction between Eu^(2+)and Sm^(3+)ions.
基金Contribution No. 49 from the Microcalorimetry Research Center. Project supported by the National Natural Science Foundation of China.
文摘The heat capacities of La(NCS)_3. 7H_2O and Ce(NCS)_3. 7H_2O have been measured from 13 to 300K with a fully-automated adiabatic calorimeter. The construction and procedures of the calorimetric system are described in detail. No obvious thermal anomaly was observed for both compounds in the experimental temperature range. The polynomial equations for calculating the heat capacity values of the two compounds in the range 13—300K were obtained by the least-squares fitting based on the experimental C_p data. The C_p values below 13K were estimated by using the Debye and Einstein heat Capacity functions. The standard molar thermodynamic functions were calculated from 0 to 300K. Gibbs energies of formation were also calculated.
基金This work was supported by National Natural Science Foundation of China(Nos.11834012,51620105014,91963207,91963122,51902237)National Key R&D Program of China(No.2018YFB0703603,2019YFA0704900,SQ2018YFE010905)Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT 2020e004).EPMA experiments were performed at the Center for Materials Research and Testing of Wuhan University of Technology.The S/TEM work was performed at the Nanostructure Research Center(NRC),which is supported by the Fundamental Research Funds for the Central Universities(WUT:2019III012GX).
文摘Incorporating magnetic nanoparticles in thermoelectric(TE)materials introduce magnetic interfaces with additional electron and phonon scattering mechanism for high TE performance.However,the influence of heterogeneous interfaces between magnetic nanoparticles and TE matrix on electronic and thermal transport remains elusive in the thermo-electric-magnetic nanocomposites.Here,using p-type TE material Bi_(0.3)Sb_(1.7)Te_(3)(BST)as matrix and magnetocaloric(MC)material La(Fe_(0.92)Co_(0.08))_(11.9)Si_(1.1)(LFS)nanoparticles as a second phase,TE/MC nanocomposites xLFS/BST(x=0.1%,0.2%,0.3% and 0.4%)were synthesized using spark plasma sintering method.The atomic-resolution interfacial structures demonstrate that Te vacancies originating from LFS-BST interfacial reaction decreases the hole concentration of the LFS/BST nanocomposites and enhances the Seebeck coefficient.The LFS/BST nanocomposites exhibit lower thermal conductivity due to enhanced phonon scattering by interfaces and defects.All the nanocomposites have higher ZT than BST matrix,with 0.2% LFS/BST nanocomposite achieving highest ZT=1.11 at 380 K.At working current 1.4 A,the device fabricated using 0.2% LFS/BST nanocomposite achieves maximal cooling temperature 4.9 K,which is 58% higher than the matrix.Moreover,the MC properties are retained in all the nanocomposites,which make them a promising candidate to achieve high TE performance and dual TE/MC properties for future applications.
基金supported by the Fundamental Research Funds for the Central Universities(No.2021JCCXJD01)Key R&D and transformation projects in Qinghai Province(No.2021-HZ-808)Hebei Province(No.21314401D)。
文摘Lithium-rich manganese-based material shows great potential as the high specific cathode materials due to its low cost,environmental friendliness,high operating voltage and simple preparation process.However,the poor capacity retention and cycling performance caused by its unstable structure during cycling restrict the commercialization.In this work,Li_(1.2)Ni_(0.16)Mn_(0.56)Co_(0.08)O_(2)was synthesized utilizing a Coprecipitation method and different amount of La(PO_(3))_(3)(La(PO_(3))_(3)=2 wt%,4 wt%and 6 wt%)was selected as the coating layer to resolve the above issues.During the calcination process,La(PO_(3))_(3)reacts with impurities such as Li OH and Li_(2)CO_(3)on the lithium-rich surface to reduce the residual lithium on the surface,thus improving the interfacial stability,slowing down the corrosion of the electrolyte,and finally enhancing its electrochemical performance.The cathode materials coated with 4%of La(PO_(3))_(3)showed the best electrochemical performance in terms of capacity retention and cycling performance compared to the pristine NCM.The high initial discharge capacity of 214.21 m Ah/g and capacity retention of 94.2%after 100 cycles at 0.1 C can be obtained.This work provides an effective strategy to protect the cathode from corrosion and will promote its further practical applications in high specific Li-ion batteries.
