A new compound Sr6Sn2Nb8O30 was found in the ternary system of SrO-SnO2-Nb2O5. The transparent colorless crystal with needle-like shape can be grown by flux method. The crystal structure of new compound was determined...A new compound Sr6Sn2Nb8O30 was found in the ternary system of SrO-SnO2-Nb2O5. The transparent colorless crystal with needle-like shape can be grown by flux method. The crystal structure of new compound was determined by X-ray diffraction, and its belongs to tungsten bronze structure. Sr6Sn2Nb8O30 crystallizes in orthorhombic system with unit cell parameters a= 17. 579 (DA,6= 17. 509(DA,c=7. 7880(5)A,Z = 4 and space group Cmm2.展开更多
High-quality Sr_(2)CrWO_(6)(SCWO) films have been grown on SrTiO_(3)(STO) substrate by pulsed laser deposition under low oxygen pressure. With decrease of the film thickness, a drastic conductivity increase is observe...High-quality Sr_(2)CrWO_(6)(SCWO) films have been grown on SrTiO_(3)(STO) substrate by pulsed laser deposition under low oxygen pressure. With decrease of the film thickness, a drastic conductivity increase is observed. The Hall measurements show that the thicker the film, the lower the carrier density. An extrinsic mechanism of charge doping due to the dominance of oxygen vacancies at SCWO/STO interfaces is proposed. The distribution and gradient of carrier concentration in SCWO films are considered to be related to this phenomenon. Resistivity behavior observed in these films is found to follow the variable range hopping model. It is revealed that with increase of the film thickness, the extent of disorder in the lattice increases, which gives a clear evidence of disorder-induced localization charge carriers in these films.Magnetoresistance measurements show that there is a negative magnetoresistance in SCWO films, which is considered to be caused by the magnetic scattering of magnetic elements Cr^(3+) and W^(5+). In addition, a sign reversal of anisotropic magnetoresistance(AMR) in SCWO film is observed for the first time, when the temperature varies across a characteristic value, T_(M). Magnetization-temperature measurements demonstrate that this AMR sign reversal is caused by the direction transition of easy axis of magnetization from the in-plane ferromagnetic order at T > T_(M) to the out-of-plane at T < T_(M).展开更多
Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as ...Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as a mixed ionic and electronic conductor.In this work,doping of In^(3+)greatly increases the oxygen vacancy concentration and the content of adsorbed oxygen species in Sr_(2)Fe_(1.5)Mo_(0.5−x)InxO_(6−δ)(SFMInx),and thus effectively promotes the ORR performance.As a typical example,SFMIn_(0.1)reduces the polarization resistance(R_(p))from 0.089 to 0.046Ω∙cm^(2)at 800°C,which is superior to those doped with other metal elements.In addition,SFMIn0.1 increases the peak power density from 0.92 to 1.47 W∙cm^(−2)at 800°C with humidified H_(2)as the fuel,indicating that In3+doping at the Mo site can effectively improve the performance of SOFC cathode material.展开更多
Electrochemical conversion of CO_(2)to CO is an economically feasible method for mitigating greenhouse gas emissions.Among various electrochemical approaches,solid oxide electrolysis cells(SOECs)show high potential fo...Electrochemical conversion of CO_(2)to CO is an economically feasible method for mitigating greenhouse gas emissions.Among various electrochemical approaches,solid oxide electrolysis cells(SOECs)show high potential for CO_(2)reduction reaction(CO_(2)-RR)due to their ability to operate at high temperatures,resulting in fast reaction kinetics and increased efficiency.Considering their main energy loss is still associated with the large overpotential at the fuel electrode,the development of the highly efficient and durable cathode for SOECs has been extensively searched after.Here,we propose an A-site doping strategy to enhance the properties of Sr_(2)Fe_(1.5)Mo_(0.5)O_(6−δ)(SFM),which improve its performance as a cathode in SOECs for CO_(2)-RR,demonstrating favorable activity and durability.The structural and physiochemical characterizations,together with DFT calculations,show that the partial replacement of Sr by Bi in the SFM double perovskite not only improves CO_(2) adsorption capability at the catalyst surface but also enhances oxygen ionic conduction inside the bulk oxide,resulting in enhanced CO_(2)electrocatalysis performance in SOECs.Specifically,a La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.2)O_(3−δ) (LSGM)electrolyte-supported single cell with the new Bi-doped SFM cathode demonstrates a large current density of 1620 mA cm^(−2) at a cell potential of 1.6 V at 850°C with good operational stability up to 200 h.Bi-doped SFM thus represents a highly promising cathode for ceramic CO_(2)electrolyzers and could accelerate our transition towards a carbon-neutral society.展开更多
Bright Eu3+-activated double-perovskite Sr2LaTaO6 red-emitting phosphors were successfully synthesized by a high-temperature solid-state method. Under near-ultraviolet excitation at 394 nm, optimal Sr2LaTaO6∶0.2 Eu3+...Bright Eu3+-activated double-perovskite Sr2LaTaO6 red-emitting phosphors were successfully synthesized by a high-temperature solid-state method. Under near-ultraviolet excitation at 394 nm, optimal Sr2LaTaO6∶0.2 Eu3+phosphors emitted high-brightness red light around 613 nm with the International Commission on Illumination chromaticity coordinates(0.650,0.349). Notably, the color purity can reach 92%. Impressively, the favorable thermal stability of the Sr2LaTaO6∶0.2 Eu3+phosphors was characterized by temperature-dependent emission spectra at different temperatures from 303 to 463 K, and the emission intensity at 423 K remained 73% of its value at 303 K. All of the results suggested that the as-prepared Sr2LaTaO6∶0.2 Eu3+phosphors can be used in near-ultraviolet-excitable white light-emitting diodes as a red-emitting color converter.展开更多
p-block metal composite oxides Sr_(1.36)Sb_(2)O_(6) and Sr_(2)Sb_(2)O_(7) synthesized by a hydrothermal method as photocatalysts in the degradation of tetracycline hydrochloride under UV light irradiation have been ex...p-block metal composite oxides Sr_(1.36)Sb_(2)O_(6) and Sr_(2)Sb_(2)O_(7) synthesized by a hydrothermal method as photocatalysts in the degradation of tetracycline hydrochloride under UV light irradiation have been extensively studied.The effects of synthesis conditions on the photocatalytic activity were discussed.The Sr_(1.36)Sb_(2)O_(6)-100°C-24 h-5 and Sr_(2)Sb_(2)O_(7)-150℃-24 h^(-2) samples prepared under optimal conditions exhibited remarkably different photocatalytic activities.The essential factors influencing the difference of photocatalytic performance were revealed.The results showed that the different photocatalytic activities observed for Sr_(1.36)Sb_(2)O_(6)and Sr_(2)Sb_(2)O_(7) could be attributed to their different electronic and crystal structures.Our work will provide a new perspective for the screening and design of p-block metal composite oxide photocatalysts to enhance the removal of organic pollutants in the environment.展开更多
To achieve a flexible single-crystal multifunctional membrane,the freestanding process of a rigid epitaxial transition metal oxide thin film via a buffered water-dissolution sacrificial layer has attracted reasonable ...To achieve a flexible single-crystal multifunctional membrane,the freestanding process of a rigid epitaxial transition metal oxide thin film via a buffered water-dissolution sacrificial layer has attracted reasonable attentions.Owing to the difference in chemical potential,specific element affinity,and lattice constant between the target membrane and the sacrificial layer,the freestanding process may cause an indelible change of physics property once the target thin film is sensitive to the above factors.Here,the heterostructures composed of the generally adopted sacrificial layer Sr_(3)Al_(2)O_(6)(SAO)and LaMnO_(3)(LMO)have been systematically investigated.The electrical and magnetic properties of LMO show extreme sensitivity to the thickness of SAO(tSAO).Then we have also found that LMO/SAO heterostructures can exhibit the coexistence of two ferromagnetic phases,the significantly enhanced Curie temperature~342 K,and the large magnetoresistance-23.3%at 300 K,which is similar to the optimal-doped manganite such as La_(2/3)Sr_(1/3)MnO_(3).X-ray diffraction results show that continuously tunable strain from out-of-plane tension to relaxation and then to compression can be generated by adjusting tSAO.This strain can stabilize the migrated oxygen from LMO to SAO,which is induced by the large oxygen affinity difference between Bsite Mn and Al.It is believed that these unexpected electrical/magnetic phenomena are originated from the combined effects of interfacial element diffusion and strain.Our study provides a strategy for designing new magnetic phases,and a reference for the fundamental understanding of strongly correlated transition metal oxide systems in the freestanding process.展开更多
(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) ultra-fine powders were synthesized by a novel sol–gel route,and the mechanism of the reaction was discussed.SrCO_(3),BaCO_(3),oxalate niobium and citric acid were used to initiate the ...(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) ultra-fine powders were synthesized by a novel sol–gel route,and the mechanism of the reaction was discussed.SrCO_(3),BaCO_(3),oxalate niobium and citric acid were used to initiate the sol–gel process,and ethylene glycol(EG)was added to further polymerize the cross-linking structure.The evolution of the(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) phase,the reaction process and the microstructures were investigated by X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared spectroscopy,DSC-TG and scanning electron microscopy.The synthesis temperature of the(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) powders reached as low as 1200℃,and the size and morphology of the powders were controlled by temperature.By adjusting the calcination temperature,we obtained(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) powders with uniform sizes of 20 nm to 500 nm.Then,dense(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) ceramics were successfully prepared using these ultrafine powders.Finally,an enhanced electrocaloric effect(ECE)value of 0.35℃ was obtained at 100 kV/cm.展开更多
基金Funded by International Centre for Diffraction Data(ICDD).
文摘A new compound Sr6Sn2Nb8O30 was found in the ternary system of SrO-SnO2-Nb2O5. The transparent colorless crystal with needle-like shape can be grown by flux method. The crystal structure of new compound was determined by X-ray diffraction, and its belongs to tungsten bronze structure. Sr6Sn2Nb8O30 crystallizes in orthorhombic system with unit cell parameters a= 17. 579 (DA,6= 17. 509(DA,c=7. 7880(5)A,Z = 4 and space group Cmm2.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 92065110, 11974048, and 12074334)。
文摘High-quality Sr_(2)CrWO_(6)(SCWO) films have been grown on SrTiO_(3)(STO) substrate by pulsed laser deposition under low oxygen pressure. With decrease of the film thickness, a drastic conductivity increase is observed. The Hall measurements show that the thicker the film, the lower the carrier density. An extrinsic mechanism of charge doping due to the dominance of oxygen vacancies at SCWO/STO interfaces is proposed. The distribution and gradient of carrier concentration in SCWO films are considered to be related to this phenomenon. Resistivity behavior observed in these films is found to follow the variable range hopping model. It is revealed that with increase of the film thickness, the extent of disorder in the lattice increases, which gives a clear evidence of disorder-induced localization charge carriers in these films.Magnetoresistance measurements show that there is a negative magnetoresistance in SCWO films, which is considered to be caused by the magnetic scattering of magnetic elements Cr^(3+) and W^(5+). In addition, a sign reversal of anisotropic magnetoresistance(AMR) in SCWO film is observed for the first time, when the temperature varies across a characteristic value, T_(M). Magnetization-temperature measurements demonstrate that this AMR sign reversal is caused by the direction transition of easy axis of magnetization from the in-plane ferromagnetic order at T > T_(M) to the out-of-plane at T < T_(M).
基金acknowledge the Autonomous Region Key Research Project(No.2022D02D31)the Graduate Education Innovation Project(No.XJ2022G046)。
文摘Promoting the oxygen reduction reaction(ORR)is critical for commercialization of intermediate-temperature solid oxide fuel cells(IT-SOFCs),where Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)−δ(SFM)is a promising cathode by working as a mixed ionic and electronic conductor.In this work,doping of In^(3+)greatly increases the oxygen vacancy concentration and the content of adsorbed oxygen species in Sr_(2)Fe_(1.5)Mo_(0.5−x)InxO_(6−δ)(SFMInx),and thus effectively promotes the ORR performance.As a typical example,SFMIn_(0.1)reduces the polarization resistance(R_(p))from 0.089 to 0.046Ω∙cm^(2)at 800°C,which is superior to those doped with other metal elements.In addition,SFMIn0.1 increases the peak power density from 0.92 to 1.47 W∙cm^(−2)at 800°C with humidified H_(2)as the fuel,indicating that In3+doping at the Mo site can effectively improve the performance of SOFC cathode material.
基金financially supported by the State Key Laboratory of Clean Energy Utilization(Open Fund Project No.ZJUCEU2021001)Natural Science Foundation of Jiangsu Province(No.BK20221312).
文摘Electrochemical conversion of CO_(2)to CO is an economically feasible method for mitigating greenhouse gas emissions.Among various electrochemical approaches,solid oxide electrolysis cells(SOECs)show high potential for CO_(2)reduction reaction(CO_(2)-RR)due to their ability to operate at high temperatures,resulting in fast reaction kinetics and increased efficiency.Considering their main energy loss is still associated with the large overpotential at the fuel electrode,the development of the highly efficient and durable cathode for SOECs has been extensively searched after.Here,we propose an A-site doping strategy to enhance the properties of Sr_(2)Fe_(1.5)Mo_(0.5)O_(6−δ)(SFM),which improve its performance as a cathode in SOECs for CO_(2)-RR,demonstrating favorable activity and durability.The structural and physiochemical characterizations,together with DFT calculations,show that the partial replacement of Sr by Bi in the SFM double perovskite not only improves CO_(2) adsorption capability at the catalyst surface but also enhances oxygen ionic conduction inside the bulk oxide,resulting in enhanced CO_(2)electrocatalysis performance in SOECs.Specifically,a La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(0.2)O_(3−δ) (LSGM)electrolyte-supported single cell with the new Bi-doped SFM cathode demonstrates a large current density of 1620 mA cm^(−2) at a cell potential of 1.6 V at 850°C with good operational stability up to 200 h.Bi-doped SFM thus represents a highly promising cathode for ceramic CO_(2)electrolyzers and could accelerate our transition towards a carbon-neutral society.
基金supported by the National Natural Science Foundation of China (No. 51502190)Young Sanjin Scholars Distinguished Professor Program of Shanxi Province+1 种基金Open Fund of the State Key Laboratory of Luminescent Materials and Devices (South China University of Technology, No. 2020-skllmd-01)Graduate Education Innovation Project of Shanxi Province。
文摘Bright Eu3+-activated double-perovskite Sr2LaTaO6 red-emitting phosphors were successfully synthesized by a high-temperature solid-state method. Under near-ultraviolet excitation at 394 nm, optimal Sr2LaTaO6∶0.2 Eu3+phosphors emitted high-brightness red light around 613 nm with the International Commission on Illumination chromaticity coordinates(0.650,0.349). Notably, the color purity can reach 92%. Impressively, the favorable thermal stability of the Sr2LaTaO6∶0.2 Eu3+phosphors was characterized by temperature-dependent emission spectra at different temperatures from 303 to 463 K, and the emission intensity at 423 K remained 73% of its value at 303 K. All of the results suggested that the as-prepared Sr2LaTaO6∶0.2 Eu3+phosphors can be used in near-ultraviolet-excitable white light-emitting diodes as a red-emitting color converter.
基金financially supported by the National Natural Science Foundation of China(21875037,51502036)the National Key Research and Development Program of China(2016YFB0302303,2019YFC1908203)the Natural Science Foundation of Distinguished Young Scholars of Fujian Province(2019J06015)。
文摘p-block metal composite oxides Sr_(1.36)Sb_(2)O_(6) and Sr_(2)Sb_(2)O_(7) synthesized by a hydrothermal method as photocatalysts in the degradation of tetracycline hydrochloride under UV light irradiation have been extensively studied.The effects of synthesis conditions on the photocatalytic activity were discussed.The Sr_(1.36)Sb_(2)O_(6)-100°C-24 h-5 and Sr_(2)Sb_(2)O_(7)-150℃-24 h^(-2) samples prepared under optimal conditions exhibited remarkably different photocatalytic activities.The essential factors influencing the difference of photocatalytic performance were revealed.The results showed that the different photocatalytic activities observed for Sr_(1.36)Sb_(2)O_(6)and Sr_(2)Sb_(2)O_(7) could be attributed to their different electronic and crystal structures.Our work will provide a new perspective for the screening and design of p-block metal composite oxide photocatalysts to enhance the removal of organic pollutants in the environment.
基金financial support from the National Natural Science Foundation of China(No.12074149)support from the Natural Science Foundation of Shandong Province(No.ZR2020QA057)+4 种基金support from the National Natural Science Foundation of China(No.51871112)the Major Basic Research Projects of Shandong Province(No.ZR2020ZD28)the 111 Project(No.B13029)support from the Taishan Scholar Project of Shandong Province(No.ts20190939)the Independent Cultivation Program of Innovation Team of Ji’nan City(No.2021GXRC043)。
文摘To achieve a flexible single-crystal multifunctional membrane,the freestanding process of a rigid epitaxial transition metal oxide thin film via a buffered water-dissolution sacrificial layer has attracted reasonable attentions.Owing to the difference in chemical potential,specific element affinity,and lattice constant between the target membrane and the sacrificial layer,the freestanding process may cause an indelible change of physics property once the target thin film is sensitive to the above factors.Here,the heterostructures composed of the generally adopted sacrificial layer Sr_(3)Al_(2)O_(6)(SAO)and LaMnO_(3)(LMO)have been systematically investigated.The electrical and magnetic properties of LMO show extreme sensitivity to the thickness of SAO(tSAO).Then we have also found that LMO/SAO heterostructures can exhibit the coexistence of two ferromagnetic phases,the significantly enhanced Curie temperature~342 K,and the large magnetoresistance-23.3%at 300 K,which is similar to the optimal-doped manganite such as La_(2/3)Sr_(1/3)MnO_(3).X-ray diffraction results show that continuously tunable strain from out-of-plane tension to relaxation and then to compression can be generated by adjusting tSAO.This strain can stabilize the migrated oxygen from LMO to SAO,which is induced by the large oxygen affinity difference between Bsite Mn and Al.It is believed that these unexpected electrical/magnetic phenomena are originated from the combined effects of interfacial element diffusion and strain.Our study provides a strategy for designing new magnetic phases,and a reference for the fundamental understanding of strongly correlated transition metal oxide systems in the freestanding process.
基金National Natural Science Foundation of China under Grant No.51202215Natural Science Foundation of Zhejiang Province under Grant No.LY15E02003Chinese National Basic Research Program under Grant No.2015CB654601.
文摘(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) ultra-fine powders were synthesized by a novel sol–gel route,and the mechanism of the reaction was discussed.SrCO_(3),BaCO_(3),oxalate niobium and citric acid were used to initiate the sol–gel process,and ethylene glycol(EG)was added to further polymerize the cross-linking structure.The evolution of the(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) phase,the reaction process and the microstructures were investigated by X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared spectroscopy,DSC-TG and scanning electron microscopy.The synthesis temperature of the(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) powders reached as low as 1200℃,and the size and morphology of the powders were controlled by temperature.By adjusting the calcination temperature,we obtained(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) powders with uniform sizes of 20 nm to 500 nm.Then,dense(Sr_(0.5)Ba_(0.5))Nb_(2)O_(6) ceramics were successfully prepared using these ultrafine powders.Finally,an enhanced electrocaloric effect(ECE)value of 0.35℃ was obtained at 100 kV/cm.