A long decay luminescent powder based upon the strontium aluminum oxide system with Eu2+ as the activator was produced. It was found that the variation of the molar ratio of Al to Sr leads to a change in emission colo...A long decay luminescent powder based upon the strontium aluminum oxide system with Eu2+ as the activator was produced. It was found that the variation of the molar ratio of Al to Sr leads to a change in emission color. The two emission centers responsible for the color change have been identified.展开更多
The commercialization of solid oxide fuel cells depends on the cathode,which possesses both high catalytic activity and a thermal-expansion coefficient(TEC)that aligns with the electrolyte.Although the cobalt-based ca...The commercialization of solid oxide fuel cells depends on the cathode,which possesses both high catalytic activity and a thermal-expansion coefficient(TEC)that aligns with the electrolyte.Although the cobalt-based cathode La_(0.6)Sr_(0.4)CoO_(3)(LSC)offers excellent catalytic performance,its TEC is significantly larger than that of the electrolyte.In this study,we mechanically mix Sm_(0.2)Ce_(0.8)O_(2−δ)(SDC)with LSC to create a composite cathode.By incorporating 50wt%SDC,the TEC decreases significantly from 18.29×10^(−6) to 13.90×10^(−6) K^(−1).Under thermal-shock conditions ranging from room temperature to 800℃,the growth rate of polarization resistance is only 0.658%per cycle,i.e.,merely 49%that of pure LSC.The button cell comprising the LSC-SDC composite cathode operates stably for over 900 h without Sr segregation,with a voltage growth rate of 1.11%/kh.A commercial flat-tube cell(active area:70 cm^(2))compris-ing the LSC-SDC composite cathode delivers 54.8 W at 750℃.The distribution of relaxation-time shows that the non-electrode portion is the main rate-limiting step.This study demonstrates that the LSC-SDC mixture strategy effectively improves the compatibility with the electrolyte while maintaining a high output,thus rendering it a promising commercial cathode material.展开更多
Considering the compatibility between degradation and bioactivity of magnesium-based implants for bone repair, micro-arc oxidation is used to modify the magnesium alloy surface in aqueous electrolytes, allowing stront...Considering the compatibility between degradation and bioactivity of magnesium-based implants for bone repair, micro-arc oxidation is used to modify the magnesium alloy surface in aqueous electrolytes, allowing strontium, calcium, and phosphorus to be incorporated into the coating. The thickness, composition, morphology and phase of this Sr-Ca-P containing coating are characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer and X-ray diffraction. The in vitro and in vivo degradation of the coating is evaluated by immersion test, electrochemical test and implantation test. Moreover, the cytocompatibility is tested with osteoblast cell according to ISO 10993. The results show that St, Ca and P elements are incorporated into the oxide coating, and a refined structure with tiny discharging micro-pores is observed on the surface of the coating. The Sr-Ca-P coating possesses a better corrosion resistance in vitro and retards the degradation in vivo. Such coating is expected to have significant medical applications on orthopedic implants and bone repair materials.展开更多
Composites consisting of strontium stabilized bismuth oxide （Bi1.14Sr0.43O2.14, SSB） and silver were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria electrolyte. There w...Composites consisting of strontium stabilized bismuth oxide （Bi1.14Sr0.43O2.14, SSB） and silver were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria electrolyte. There were no chemical reactions between the two components. The microstructure of the interfaces between composite cathodes and Ce0.8Sm0.2O1.9 （SDC） electrolytes was examined by scanning electron microscopy （SEM）. Impedance spectroscopy measurements show that the performance of cathode fired at 700 ℃ is the best. When the content of Ag2O is 70 wt%, polarization resistance values for the SSB-Ag cathodes are as low as 0.2 Ωcm^2 at 700℃ and 0.29 Ωcm^2 at 650℃. These results are much smaller than some of other reported composite cathodes on doped ceria electrolyte and indicate that SSB-Ag composite is a potential cathode material for intermediate temperature SOFCs.展开更多
The collection of different cations in the A and B sites of ABO3 was explored for the regularity of perovskites phase formability.Here,Sr2？,La3？,and Ce4？are selected as the cations of site A.The site B is considere...The collection of different cations in the A and B sites of ABO3 was explored for the regularity of perovskites phase formability.Here,Sr2？,La3？,and Ce4？are selected as the cations of site A.The site B is considered to be Mn or Co cations.XRD analysis and Fourier transform infrared spectroscopy results confirm the formation of perovskite structure for catalysts in which La3？and Sr2？are considered as the cations of site A.Ceria is detected as the main crystalline phase when Ce4？is selected to be cation of site A.It is found that the octahedral factor（rB/rO） takes the same important role as the tolerance factor to form cubic perovskite.Average crystallite size of the products was calculated by data of the XRD and measured by the TEM analysis.Results of the XRD and TEM studies were supported by the study of the particles size distribution,which was carried out in a particle size analyzer.The perovskite samples were also used for stoichiometric oxidation of carbon monoxide with air.展开更多
The oxidative coupling of methane(OCM)isone of the most promising routes for the direct con-version of methane to ethylene[1].Ding et al[2]re-ported that a high surface concentration of alkaline earth metal cations fa...The oxidative coupling of methane(OCM)isone of the most promising routes for the direct con-version of methane to ethylene[1].Ding et al[2]re-ported that a high surface concentration of alkaline earth metal cations facilitated the formation of C_(2) hy-drocarbons during the OCM.Surface basicity is nec-essary for the OCM,and oxygen adsorbed on basic sites is also indispensable.The adsorbed electron defi-cient oxygen species on the catalyst surface plays a crucial role in methane conversion and the selectivity for Cz hydrocarbons.Our previous study[3]showed that increasing the Sr/Ti molar ratio in the per-ovskite-type SrTiO_(3) catalyst resulted in the surface enrichment of Sr,a larger amount of adsorbed oxygen species and higher selectivity for C_(2) hydrocarbons in the OCM.Recently,nanocatalysts have attracted much attention because of their remarkable catalytic performance[4.5].展开更多
Considering the high melting point and high stability of SrO,it has potential applications in the field of the preparation of titanium alloys.To improve the hydration resistance,SrO samples with different ZrO_(2)addit...Considering the high melting point and high stability of SrO,it has potential applications in the field of the preparation of titanium alloys.To improve the hydration resistance,SrO samples with different ZrO_(2)additions were fabricated after firing at 1750℃for 6 h.The phase,the microstructure,and the hydration resistance of the samples were researched.The results show that the sample with 33 mol%ZrO_(2)addition possesses good hydration resistance with the mass gain after hydration for 13 days of less than 0.42 mass%.The SrO crucible with 33 mol%ZrO_(2)addition does not react with TiNi alloy melt during melting,which provides a support for searching new refractories with good hydration resistance for induction melting titanium alloys.展开更多
Development of high performance electrocatalysts for oxygen evolution reaction (OER) in acidic media remains a challenge for direct water splitting using an electrolyzer.Recently,Ruddlesden-Popper phase Sr_(2)IrO_(4)w...Development of high performance electrocatalysts for oxygen evolution reaction (OER) in acidic media remains a challenge for direct water splitting using an electrolyzer.Recently,Ruddlesden-Popper phase Sr_(2)IrO_(4)was discovered to be an efficient OER catalyst because of its unique structure,which consists of layers of both rock salt and perovskite phases simultaneously.In this study,we prepared a series of B-site mixed,Ruddlesden-Popper phase of Sr_(2)(Ru_(x)Ir_(1-x))O_(4) and examined their electrocatalytic properties for OER in acidic media.Through partial substitution of Ru in the B-site of Ruddlesden-Popper phase materials,we achieved much enhanced OER performance for this series of Sr_(2)(Ru_(x)Ir_(1-x))O_(4)electrocatalysts,among which Sr_(2)(Ru_(0.5)Ir_(0.5))O_(4)exhibited the best catalytic activity with a current density of 8.06 m A/cm^(2) at 1.55 V and a Tafel slope of 47 m V/dec.This current density is three times higher than that of Sr_(2)Ir O_(4).The B-site mixed Sr_(2)(Ru_(0.5)Ir_(0.5))O_(4)retained good stability in acidic conditions for>24 h at 10 m A/cm^(2).A range of techniques were used to characterize the crystal and electronic structures of the Sr_(2)(Ru_(x)Ir_(1-x))O_(4)samples.Our data indicate that the improved OER performance can be correlated to the formation of high level of hydroxyl groups and the enhanced overlap between Ir/Ru 4d and O_(2)p orbitals,revealing a new way for the design of efficient OER electrocatalysts by regulating their composition and electronic structures.展开更多
Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been ...Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories： growth-related tuning （i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers） and post-growth tuning （i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates）. Taken together, these methods enable the broad tuning of the electronic properties of this interface.展开更多
New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure ...New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.展开更多
文摘A long decay luminescent powder based upon the strontium aluminum oxide system with Eu2+ as the activator was produced. It was found that the variation of the molar ratio of Al to Sr leads to a change in emission color. The two emission centers responsible for the color change have been identified.
基金the financial support from the National Natural Science Foundation of China(No.22209191)Ningbo Key R&D Project(No.2023Z155).
文摘The commercialization of solid oxide fuel cells depends on the cathode,which possesses both high catalytic activity and a thermal-expansion coefficient(TEC)that aligns with the electrolyte.Although the cobalt-based cathode La_(0.6)Sr_(0.4)CoO_(3)(LSC)offers excellent catalytic performance,its TEC is significantly larger than that of the electrolyte.In this study,we mechanically mix Sm_(0.2)Ce_(0.8)O_(2−δ)(SDC)with LSC to create a composite cathode.By incorporating 50wt%SDC,the TEC decreases significantly from 18.29×10^(−6) to 13.90×10^(−6) K^(−1).Under thermal-shock conditions ranging from room temperature to 800℃,the growth rate of polarization resistance is only 0.658%per cycle,i.e.,merely 49%that of pure LSC.The button cell comprising the LSC-SDC composite cathode operates stably for over 900 h without Sr segregation,with a voltage growth rate of 1.11%/kh.A commercial flat-tube cell(active area:70 cm^(2))compris-ing the LSC-SDC composite cathode delivers 54.8 W at 750℃.The distribution of relaxation-time shows that the non-electrode portion is the main rate-limiting step.This study demonstrates that the LSC-SDC mixture strategy effectively improves the compatibility with the electrolyte while maintaining a high output,thus rendering it a promising commercial cathode material.
基金financially supported by the National High Technology Research and Development Program of China (No. 2015AA033701)the Chinese Academy of Sciences-Croucher Founding Scheme for Joint Laboratories (Ref. CAS 14303)Foundation of Jiangsu Collaborative Innovation Center of Biomedical Functional Materials
文摘Considering the compatibility between degradation and bioactivity of magnesium-based implants for bone repair, micro-arc oxidation is used to modify the magnesium alloy surface in aqueous electrolytes, allowing strontium, calcium, and phosphorus to be incorporated into the coating. The thickness, composition, morphology and phase of this Sr-Ca-P containing coating are characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer and X-ray diffraction. The in vitro and in vivo degradation of the coating is evaluated by immersion test, electrochemical test and implantation test. Moreover, the cytocompatibility is tested with osteoblast cell according to ISO 10993. The results show that St, Ca and P elements are incorporated into the oxide coating, and a refined structure with tiny discharging micro-pores is observed on the surface of the coating. The Sr-Ca-P coating possesses a better corrosion resistance in vitro and retards the degradation in vivo. Such coating is expected to have significant medical applications on orthopedic implants and bone repair materials.
基金Funded by the National Natural Science Foundation of China(No.20576063)the 973 Project of Ministry of Science and Technology in China(No.T2000026410)
文摘Composites consisting of strontium stabilized bismuth oxide （Bi1.14Sr0.43O2.14, SSB） and silver were investigated as cathodes for intermediate-temperature solid oxide fuel cells with doped ceria electrolyte. There were no chemical reactions between the two components. The microstructure of the interfaces between composite cathodes and Ce0.8Sm0.2O1.9 （SDC） electrolytes was examined by scanning electron microscopy （SEM）. Impedance spectroscopy measurements show that the performance of cathode fired at 700 ℃ is the best. When the content of Ag2O is 70 wt%, polarization resistance values for the SSB-Ag cathodes are as low as 0.2 Ωcm^2 at 700℃ and 0.29 Ωcm^2 at 650℃. These results are much smaller than some of other reported composite cathodes on doped ceria electrolyte and indicate that SSB-Ag composite is a potential cathode material for intermediate temperature SOFCs.
文摘The collection of different cations in the A and B sites of ABO3 was explored for the regularity of perovskites phase formability.Here,Sr2？,La3？,and Ce4？are selected as the cations of site A.The site B is considered to be Mn or Co cations.XRD analysis and Fourier transform infrared spectroscopy results confirm the formation of perovskite structure for catalysts in which La3？and Sr2？are considered as the cations of site A.Ceria is detected as the main crystalline phase when Ce4？is selected to be cation of site A.It is found that the octahedral factor（rB/rO） takes the same important role as the tolerance factor to form cubic perovskite.Average crystallite size of the products was calculated by data of the XRD and measured by the TEM analysis.Results of the XRD and TEM studies were supported by the study of the particles size distribution,which was carried out in a particle size analyzer.The perovskite samples were also used for stoichiometric oxidation of carbon monoxide with air.
基金Supported by the National Key Project for Basic Research of China(973 Project)(G1999022400).
文摘The oxidative coupling of methane(OCM)isone of the most promising routes for the direct con-version of methane to ethylene[1].Ding et al[2]re-ported that a high surface concentration of alkaline earth metal cations facilitated the formation of C_(2) hy-drocarbons during the OCM.Surface basicity is nec-essary for the OCM,and oxygen adsorbed on basic sites is also indispensable.The adsorbed electron defi-cient oxygen species on the catalyst surface plays a crucial role in methane conversion and the selectivity for Cz hydrocarbons.Our previous study[3]showed that increasing the Sr/Ti molar ratio in the per-ovskite-type SrTiO_(3) catalyst resulted in the surface enrichment of Sr,a larger amount of adsorbed oxygen species and higher selectivity for C_(2) hydrocarbons in the OCM.Recently,nanocatalysts have attracted much attention because of their remarkable catalytic performance[4.5].
基金supported by the Independent Research and Development Project of the State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS 2021-03)National Science Fund for Distinguished Young Scholars(No.52025041)National Natural Science Foundation of China(Grant No.52104305)
文摘Considering the high melting point and high stability of SrO,it has potential applications in the field of the preparation of titanium alloys.To improve the hydration resistance,SrO samples with different ZrO_(2)additions were fabricated after firing at 1750℃for 6 h.The phase,the microstructure,and the hydration resistance of the samples were researched.The results show that the sample with 33 mol%ZrO_(2)addition possesses good hydration resistance with the mass gain after hydration for 13 days of less than 0.42 mass%.The SrO crucible with 33 mol%ZrO_(2)addition does not react with TiNi alloy melt during melting,which provides a support for searching new refractories with good hydration resistance for induction melting titanium alloys.
基金supported in part by the US National Science Foundation(NSF-2055734)a start-up fund from University of Illinois at Urbana-Champaignthe support of a scholarship from the China Scholarship Council(CSC)。
文摘Development of high performance electrocatalysts for oxygen evolution reaction (OER) in acidic media remains a challenge for direct water splitting using an electrolyzer.Recently,Ruddlesden-Popper phase Sr_(2)IrO_(4)was discovered to be an efficient OER catalyst because of its unique structure,which consists of layers of both rock salt and perovskite phases simultaneously.In this study,we prepared a series of B-site mixed,Ruddlesden-Popper phase of Sr_(2)(Ru_(x)Ir_(1-x))O_(4) and examined their electrocatalytic properties for OER in acidic media.Through partial substitution of Ru in the B-site of Ruddlesden-Popper phase materials,we achieved much enhanced OER performance for this series of Sr_(2)(Ru_(x)Ir_(1-x))O_(4)electrocatalysts,among which Sr_(2)(Ru_(0.5)Ir_(0.5))O_(4)exhibited the best catalytic activity with a current density of 8.06 m A/cm^(2) at 1.55 V and a Tafel slope of 47 m V/dec.This current density is three times higher than that of Sr_(2)Ir O_(4).The B-site mixed Sr_(2)(Ru_(0.5)Ir_(0.5))O_(4)retained good stability in acidic conditions for>24 h at 10 m A/cm^(2).A range of techniques were used to characterize the crystal and electronic structures of the Sr_(2)(Ru_(x)Ir_(1-x))O_(4)samples.Our data indicate that the improved OER performance can be correlated to the formation of high level of hydroxyl groups and the enhanced overlap between Ir/Ru 4d and O_(2)p orbitals,revealing a new way for the design of efficient OER electrocatalysts by regulating their composition and electronic structures.
基金Project supported by the Department of Energy,Office of Basic Energy Sciences(Grant No.DE-AC02-76SF00515)
文摘Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories： growth-related tuning （i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers） and post-growth tuning （i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates）. Taken together, these methods enable the broad tuning of the electronic properties of this interface.
文摘New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.
