High-entropy materials(HEMs)have better mechanical,thermal,and electrical properties than traditional materials due to their special"high entropy effect".They can also adjust the performance of high entropy ...High-entropy materials(HEMs)have better mechanical,thermal,and electrical properties than traditional materials due to their special"high entropy effect".They can also adjust the performance of high entropy ceramics by adjusting the proportion of raw materials,and have broad application prospects in many fields.This article provides a review of the high entropy effect,preparation methods,and main applications of high entropy ceramic materials,especially exploring relevant research on high entropy perovskite ceramics.It is expected to provide reference for the promotion of scientific research and the development of further large-scale applications of high-entropy ceramic materials.展开更多
Composite perovskite piezoelectric ceramics of PMMN quaternary system were prepared by cold-pressing and solid-phase sintering. Piezoelectric modulus and density of the samples were measured after polarization. X-ray ...Composite perovskite piezoelectric ceramics of PMMN quaternary system were prepared by cold-pressing and solid-phase sintering. Piezoelectric modulus and density of the samples were measured after polarization. X-ray diffraction analysis and SEM were used to prove the result that the major phase of the piezoelectric ceramic spectimen based on PZT is PZT phase,which is tetragonal system and P-4mm space group.展开更多
La_(0.68)Pb_(0.32)FeO_3 samples annealed at different temperature were prepared using citrate sol-gel method. With increasing of annealing temperature from 200 to 1000 ℃, the samples crystallize to have single-phase ...La_(0.68)Pb_(0.32)FeO_3 samples annealed at different temperature were prepared using citrate sol-gel method. With increasing of annealing temperature from 200 to 1000 ℃, the samples crystallize to have single-phase perovskite structure. However, the sensitivity increases at first due to the improvement of crystallization of the perovskite phase, and finally drops attributed to the larger grain size. The optimal sensitivities for La_(0.68)Pb_(0.32)FeO_3 samples annealed at 400, 600, 800, and 1000 ℃ are 12.14, 14.77, 51.07, and 34.55, respectively.展开更多
The electronic structures, optical dielectric functions, elastic properties, and lattice dynamics of Ba2ZnWO6 have been investigated by using the generalized gradient approximation. The density of states and distribut...The electronic structures, optical dielectric functions, elastic properties, and lattice dynamics of Ba2ZnWO6 have been investigated by using the generalized gradient approximation. The density of states and distributions of charge density show that O and Ba tend toward ionic bond, but O and W or Zn display the covalent bond character. The calculated energy band structure shows that Ba2ZnWO6 is a wide indirect band gap semiconductor. The static value 2.28 of the refractive index is attained. The analysis of the elastic properties of Ba2ZnWO6 indicates a rather weak elastic anisotropy. The phonon dispersion is calculated, suggesting no structural instability, which is agreement with the recent low temperature neutron diffraction experiments. The mensurability Cv (phonon heat capacity) as the function of the temperature is also calculated to judge our results for future experiment.展开更多
Perovskite structure La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ)(LSCM) cathode with unique structure can electrolyze CO_2 to CO in solid oxide electrolysers(SOEs).However,the cell performance is restricte...Perovskite structure La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ)(LSCM) cathode with unique structure can electrolyze CO_2 to CO in solid oxide electrolysers(SOEs).However,the cell performance is restricted by its electro-catalysis activity.In this work,fluorite structure nanoparticles(CeO_(2-δ)) are impregnated on LSCM cathode to improve the electro-catalysis activity.X-ray diffraction(XRD),scanning electron microscope(SEM) and X-ray photoelectron spectroscopy(XPS) together approve that the fluorite structure nanoparticles are uniformly distributed on the perovskite structure LSCM scaffold.Electrochemical measurements illustrate that direct CO_2 electrolysis with 10%mol CeO_(2-δ) impregnated LSCM cathode exhibits excellent performance for current density(0.5 A×cm^(-2)) and current efficiency(~95%) at 800 ℃ under 1.6 V.It is believed that the enhanced performance of directed CO_2 electrolysis may be due to the synergetic effect of fluorite structure CeO_(2-δ) nanoparticles and perovskite structure LSCM ceramic electrode.展开更多
The replaced site of Eu^(2+) ion is dependent on the electronegativity difference of the cations in complex fluorides.In the mixed fluoride KMgF_3:Eu^(2+),Eu^(2+) ion occupies K^+ site,its emission spectrum is a sharp...The replaced site of Eu^(2+) ion is dependent on the electronegativity difference of the cations in complex fluorides.In the mixed fluoride KMgF_3:Eu^(2+),Eu^(2+) ion occupies K^+ site,its emission spectrum is a sharp line and its valence-state is stable.展开更多
ZnO single crystal was used as the substrate to study the effect of ZnO crystal plane polarity on the morphology and structure of CH_3NH_3PbI_3(MAPbI_3) perovskite film and carrier transport properties,which is mean...ZnO single crystal was used as the substrate to study the effect of ZnO crystal plane polarity on the morphology and structure of CH_3NH_3PbI_3(MAPbI_3) perovskite film and carrier transport properties,which is meaningful for improving ZnO-based perovskite solar cell. It is found that perovskite thin film has small grain size(about 190 nm) and high coverage rate on the O-face of ZnO single crystal,and the dominant exposed crystal plane of perovskite film is(110) plane. While the MAPbI_3 thin film has large grain size(about 1.03 μm) and low coverage rate on the Zn-face,and the(022) plane is dominantly exposed for the perovskite film. The injection of photogenerated electrons from MAPbI_3 film into the O-face of ZnO single crystal is faster and more effective than that to Zn-face. It is supposed that O-face is more suitable for ZnO single crystal based perovskite cell fabrication than Zn-face.展开更多
The phase diagram of the CsBr-CaBr2 system was re-determined by using differential thermal analysis and high ternperature and room ternperature X-ray diffraction analysis. It is concluded that there are three intermed...The phase diagram of the CsBr-CaBr2 system was re-determined by using differential thermal analysis and high ternperature and room ternperature X-ray diffraction analysis. It is concluded that there are three intermediate compounds in this system: a.congruently melting compound, CsCaBr3, with a melting point of 823℃ and two incongruently melting compounds, Cs2CaBr4 and Cs3Ca2Br7, whose peritectic points being 597℃ and 635℃, respectively. X-ray diffraction analysis indicated that compound CsCaBr3 is of slightly distorted perovskite structure.展开更多
La0.75Sr0.25CryMn1-yO3 (LSCM) (y = 0.0-0.6) composite oxides were synthesized by a complexing process of combining ethylene diamine tetraacetic acid (EDTA) and citrate. X-ray diffraction (XRD), temperature-pro...La0.75Sr0.25CryMn1-yO3 (LSCM) (y = 0.0-0.6) composite oxides were synthesized by a complexing process of combining ethylene diamine tetraacetic acid (EDTA) and citrate. X-ray diffraction (XRD), temperature-programmed reduction, electrical conductivity, I-V polarization, and impedance spectroscopy were conducted to investigate the Cr doping effect of La0.75Sr0.25MnO3 on its phase stability and electrochemical performance as a solid-oxide fuel cell (SOFC) anode. The chemical and structural stabilities of the oxides increased steadily with increasing Cr doping concentration, while the electrical conductivity decreased on the contrary. At y 〉 0.4, the basic perovskite structure under the anode operating condition was sustained. A cell with 0.5-ram-thick scandia-stabilized zirconia electrolyte and La0.75Sr0.25CryMn1-yO3 anode delivered a Dower density of -15 mW-cm^-2 at 850℃.展开更多
The perovskite-type AgTaO3 crystals were prepared by mild hydrothermal method and determined by powder X-ray diffraction. Rietveld refinement indicates that AgTaO3 crystallized in an orthorhombic system with the space...The perovskite-type AgTaO3 crystals were prepared by mild hydrothermal method and determined by powder X-ray diffraction. Rietveld refinement indicates that AgTaO3 crystallized in an orthorhombic system with the space group Pcmn. The lattice parameters are a=5.5822(1) nm, b=7.8522(2) nm and c=5.5347(1) nm, with α=β=γ= 90.0o. The compound was characterized by scanning electron microscopy(SEM), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy(HR-TEM) and UV-Vis diffuse reflectance spectrometry (UV-Vis DRS). The photocatalytic activity of AgTaO3 powder was evaluated by the degradation of Congo red under UV-light irradiation. The result shows that the titled compound has a high photocatalytic activity at room temperature and potential application in photocatalysis.展开更多
The organometal halide perovskite materials have a blend of surprising optoelectronic properties, for example high value of absorption coefficient and abrupt optical retention edge, lifetime, long charge carrier diffu...The organometal halide perovskite materials have a blend of surprising optoelectronic properties, for example high value of absorption coefficient and abrupt optical retention edge, lifetime, long charge carrier diffusion length and many more. Brought in conjunction with the capacity for manufacturing at low temperature, likewise from the solution, devices based on perovskite, particularly solar cells have been contemplated seriously with striking advancements in performance, in the course of recent years. The amalgamation of minimal effort, high efficiency and extra applications gives incredible potential to commercialization of these cells. The applications and performance of perovskite cells frequently relate with the structures of the device. Numerous creative structures of the devices were produced, targeting for vast scale manufacture, diminishing creation cost, upgrading the PCE and subsequently expanding the prospective for future applications. This paper outlines the various advanced structures of PSC, challenges confronted by these PSCs and their future perspectives. The commercial applications of PSC are additionally talked about in this paper.展开更多
Nominal composition of Ca1-xZnxTiO3 : 0. 002Pr^3 + (x = 0. 000 - 0. 200) phosphors were prepared by conventional solid reaction route. XRD and PL measurements were used to investigate the solid-solution structure ...Nominal composition of Ca1-xZnxTiO3 : 0. 002Pr^3 + (x = 0. 000 - 0. 200) phosphors were prepared by conventional solid reaction route. XRD and PL measurements were used to investigate the solid-solution structure and luminescence properties of Zn-doped Ca1-xZnxTiO3:0.002Pr^3+ phosphors. The effect of solid-solution structure formed by substitution between Ca^2 + and Zn^2+ ions on the luminescent properties was analyzed. The results reveal that, with the increase of Zn substitution content below 0.010, lattice parameters and the intensity of excitation peak at both 260 and 330 nm as well as the corresponding 610 nm emission intensity are monotonously decreased quickly in a similar tendency. Also, the evolution of luminescence intensity and crystal cell parameters against Zn doping concentration are in good agreement. Above results are closely related with the structure change within Ca1- xZnxTiO3:0.002Pr^3+ solid-solution phase formed by the Zn ions substitution for the Ca sites. Present study reveals that the solid-solution structure formed by substitution between Ca^2+ and Zn^2+ ions has significant effect on the luminescence properties of single phase Ca1-xZnxTiO3:0.002Pr^3+ phosphors.展开更多
Structure model of charge-ordered La_0.33 Ca_0.67 MnO_3, perovskite is one of current focused study in condensed matter physics. There are great discrepancies in previous studies in this field. Our transmission electr...Structure model of charge-ordered La_0.33 Ca_0.67 MnO_3, perovskite is one of current focused study in condensed matter physics. There are great discrepancies in previous studies in this field. Our transmission electron microscopy study confirms Wigner crystal model with transverse displacement and is not consisent with the hi-stripe model with longitudinal displacement. We observed incommensurate modulation and anti-phase domains with a displacement vector a_co/3 in charge--ordered La_0.33 Ca_0.67 MnO_3, perovskite.展开更多
A n-Hexyl NH 3Sr 2Nb 3O 10 is obtained by the stepwise ion-exchange reaction,then is dispersed in aqueous solution of trinuclear acetato-hydroxo iron(III) nitrate,[Fe 3(OCOCH 3) 7OH·2H 2O]NO 3,and the ...A n-Hexyl NH 3Sr 2Nb 3O 10 is obtained by the stepwise ion-exchange reaction,then is dispersed in aqueous solution of trinuclear acetato-hydroxo iron(III) nitrate,[Fe 3(OCOCH 3) 7OH·2H 2O]NO 3,and the interlayer potassium cations of the perovskite niobate are exchanged with the partially hydrolyzed trinuclear acetato complex ions.On heating,the exchanged complex ions are converted into iron oxide pillars which keep the perovskite sheets apart.The product is characterized by XRD,SEM,EDAX and surface area measurement respectively.展开更多
The effect of the distribution of organic cations CH3NH3^+(MA^+) on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuu...The effect of the distribution of organic cations CH3NH3^+(MA^+) on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuudopotentials. Generalized gradient approximation and local density approximation are used to optimize the geometries of six models, which are different in the orientation of organic cations. The results show that model C is more stable than others, and the main contribution to the top of valence band is from I 5p states. In the bottom of conduction bands, the main components are Pb 6s states with an overlapping of I 5p states. When the orientation of organic group is transforming, the Pb I6 octahedra will distort and the band structure will alter with it, which affect the generation and migration of photon-generated carriers and optical properties.展开更多
We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain...We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain model, was included in a complementary manner to lattice relaxation. Density functional theory as well as a hybrid functional method based on a plane wave basis set was employed to calculate the lattice structure, elastic constants, electronic properties and optical properties of perovskite BaZrO3. The lattice parameter c exhibited a clear linear dependence on the imposed in-plane strain, but the Poisson's ratio caused by internal relaxation was smaller than the elastic deformation, indicating an "inelastic" or "plastic" relaxation manner caused by the introduction of internal relaxation. As a result, the related electronic and optical properties of perovskite BaZrO3 were also strongly affected by the in-plane strain, which revealed an effective way to adjust the properties of perovskite BaZrO3 via internal relaxation.展开更多
A new series of multiferroic In_(1-x)Yb_(x)FeO_(3)(x=0.1,0.2,0.3) compounds were prepared using the traditional synthesis method for the first time.Partially substituting In ions in InFeO3with Yb ions results in the w...A new series of multiferroic In_(1-x)Yb_(x)FeO_(3)(x=0.1,0.2,0.3) compounds were prepared using the traditional synthesis method for the first time.Partially substituting In ions in InFeO3with Yb ions results in the weak ferroelectricity of the compound.A dielectric relaxation peak is found at ~500 K in the temperature dependence of the dielectric properties of the resulted compounds.The dielectric constant of In_(0.8)Yb_(0.2)FeO_(3)displays an anomaly at -500 K,and the ferroelectric hysteresis loop reveals its weak ferroelectric behaviors below this temperature.Similarly to InFeO_(3),the compounds crystallize in space group P63/mmc.The increase in the Yb content leads to an increment in a and a reduction in c parameters.The temperature dependence of magnetization for In_(0.8)Yb_(0.2)FeO_(3)gives a Néel temperature of -150 K.The hysteresis loops at 10 and 100 K indicate its weak ferromagnetic characteristics above room temperature.Thus,In_(1-x)Yb_(x)FeO_(3)(x=0.1,0.2,0.3) compounds show both weak ferroelectricity and weak ferromagnetism.The non-symmetry of Yb cations causes the ferroelectricity of the compounds.展开更多
MnO_(2)-modified Pb_(0.9625)Sm_(0.025)(Mg_(1/3)Nb_(2/3))_(0.71)Ti_(0.2)9O_(3) ceramics were prepared via a solid-state reaction approach.Results of detailed characterizations revealed that the addition of MnO_(2) has ...MnO_(2)-modified Pb_(0.9625)Sm_(0.025)(Mg_(1/3)Nb_(2/3))_(0.71)Ti_(0.2)9O_(3) ceramics were prepared via a solid-state reaction approach.Results of detailed characterizations revealed that the addition of MnO_(2) has influence on the grain size,and all samples exhibit a pure perovskite structure.As the content of manganese increases,the volume of tetragonal phase increases.The ceramics with 1.5 mol.%MnO_(2) show a high electro-strain of 0.151%at 2 kV/mm.Therefore,this study provides a new insight into the role of MnO_(2) addition in tailoring the electrical properties of the Sm-PMN-PT ceramics by acceptor doping.展开更多
The experimental and calculated data on the existence of complex oxides in solid state with the octahedral structures of four families,namely perovskites,Bi-containing layered perovskite-like ones,tetragonal tungsten ...The experimental and calculated data on the existence of complex oxides in solid state with the octahedral structures of four families,namely perovskites,Bi-containing layered perovskite-like ones,tetragonal tungsten bronzes and pyrochlores,and about their phase transitions are systematized and summarized on the basis of the quasi-elastic or geometric models of these structures.It has been established that similar existence areas and similar correlations between the interatomic bond strains in their structures,on the one hand,and the temperatures of their ferroelectric or antiferroelectric phase transitions,on the other hand,are observed for all of them,despite the differences in the compositions and structures of these oxides,but taking into account their similar parameters.展开更多
Molten salt synthesis (MSS) method has advantages of the simplicity in the process equipment, versatile and large-scale synthesis, and friendly environment, which provides an excellent approach to synthesize high pu...Molten salt synthesis (MSS) method has advantages of the simplicity in the process equipment, versatile and large-scale synthesis, and friendly environment, which provides an excellent approach to synthesize high pure oxide powders with controllable compositions and morphologies. Among these oxides, perovskite oxides with a composition of ABO3 exhibit a broad spectrum of physical properties and functions (e.g. ferroelectric, piezoelectric, magnetic, photovoltaic and photocatalytic properties). The downscaling of the spatial geometry of perovskite oxides into nanometers result in novel properties that are different from the bulk and film counterparts. Recent interest in nanoscience and nanotechnology has led to great efforts focusing on the synthesis of low-dimensional perovskite oxide nanostructures (PONs) to better understand their novel physical properties at nanoscale. Therefore, the low-dimensional PONs such as perovskite nanoparticles, nanowires, nanorods, nanotubes, nanofibers, nanobelts, and two dimensional oxide nanostructures, play an important role in developing the next generation of oxide electronics. In the past few years, much effort has been made on the synthesis of PONs by MSS method and their structural characterizations. The functional applications of PONs are also explored in the fields of storage memory, energy harvesting, and solar energy conversion. This review summarizes the recent progress in the synthesis of low-dimensional PONs by MSS method and its modified ways. Their structural char- acterization and physical properties are also scrutinized. The potential applications of low-dimensional PONs in different fields such as data memory and storage, energy harvesting, solar energy conversion, are highlighted. Perspectives concerning the future research trends and challenges of low-dimensional PONs are also outlined. ~ 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.展开更多
文摘High-entropy materials(HEMs)have better mechanical,thermal,and electrical properties than traditional materials due to their special"high entropy effect".They can also adjust the performance of high entropy ceramics by adjusting the proportion of raw materials,and have broad application prospects in many fields.This article provides a review of the high entropy effect,preparation methods,and main applications of high entropy ceramic materials,especially exploring relevant research on high entropy perovskite ceramics.It is expected to provide reference for the promotion of scientific research and the development of further large-scale applications of high-entropy ceramic materials.
文摘Composite perovskite piezoelectric ceramics of PMMN quaternary system were prepared by cold-pressing and solid-phase sintering. Piezoelectric modulus and density of the samples were measured after polarization. X-ray diffraction analysis and SEM were used to prove the result that the major phase of the piezoelectric ceramic spectimen based on PZT is PZT phase,which is tetragonal system and P-4mm space group.
基金Project supported by the National Natural Science Foundation of China (59772040)
文摘La_(0.68)Pb_(0.32)FeO_3 samples annealed at different temperature were prepared using citrate sol-gel method. With increasing of annealing temperature from 200 to 1000 ℃, the samples crystallize to have single-phase perovskite structure. However, the sensitivity increases at first due to the improvement of crystallization of the perovskite phase, and finally drops attributed to the larger grain size. The optimal sensitivities for La_(0.68)Pb_(0.32)FeO_3 samples annealed at 400, 600, 800, and 1000 ℃ are 12.14, 14.77, 51.07, and 34.55, respectively.
基金supported by the Fundamental Research Funds for the Central Universities (Grant No. 2013QNA32)
文摘The electronic structures, optical dielectric functions, elastic properties, and lattice dynamics of Ba2ZnWO6 have been investigated by using the generalized gradient approximation. The density of states and distributions of charge density show that O and Ba tend toward ionic bond, but O and W or Zn display the covalent bond character. The calculated energy band structure shows that Ba2ZnWO6 is a wide indirect band gap semiconductor. The static value 2.28 of the refractive index is attained. The analysis of the elastic properties of Ba2ZnWO6 indicates a rather weak elastic anisotropy. The phonon dispersion is calculated, suggesting no structural instability, which is agreement with the recent low temperature neutron diffraction experiments. The mensurability Cv (phonon heat capacity) as the function of the temperature is also calculated to judge our results for future experiment.
基金supported by the National Natural Science Foundation of China(91545123)Natural Science Foundation of Fujian Province(2016J01275)
文摘Perovskite structure La_(0.75)Sr_(0.25)Cr_(0.5)Mn_(0.5)O_(3-δ)(LSCM) cathode with unique structure can electrolyze CO_2 to CO in solid oxide electrolysers(SOEs).However,the cell performance is restricted by its electro-catalysis activity.In this work,fluorite structure nanoparticles(CeO_(2-δ)) are impregnated on LSCM cathode to improve the electro-catalysis activity.X-ray diffraction(XRD),scanning electron microscope(SEM) and X-ray photoelectron spectroscopy(XPS) together approve that the fluorite structure nanoparticles are uniformly distributed on the perovskite structure LSCM scaffold.Electrochemical measurements illustrate that direct CO_2 electrolysis with 10%mol CeO_(2-δ) impregnated LSCM cathode exhibits excellent performance for current density(0.5 A×cm^(-2)) and current efficiency(~95%) at 800 ℃ under 1.6 V.It is believed that the enhanced performance of directed CO_2 electrolysis may be due to the synergetic effect of fluorite structure CeO_(2-δ) nanoparticles and perovskite structure LSCM ceramic electrode.
基金Project supported by the National Natural Science Foundation of China
文摘The replaced site of Eu^(2+) ion is dependent on the electronegativity difference of the cations in complex fluorides.In the mixed fluoride KMgF_3:Eu^(2+),Eu^(2+) ion occupies K^+ site,its emission spectrum is a sharp line and its valence-state is stable.
基金supported by the National Natural Science Foundation of China(Nos.91333207,61427901 and U1505252)
文摘ZnO single crystal was used as the substrate to study the effect of ZnO crystal plane polarity on the morphology and structure of CH_3NH_3PbI_3(MAPbI_3) perovskite film and carrier transport properties,which is meaningful for improving ZnO-based perovskite solar cell. It is found that perovskite thin film has small grain size(about 190 nm) and high coverage rate on the O-face of ZnO single crystal,and the dominant exposed crystal plane of perovskite film is(110) plane. While the MAPbI_3 thin film has large grain size(about 1.03 μm) and low coverage rate on the Zn-face,and the(022) plane is dominantly exposed for the perovskite film. The injection of photogenerated electrons from MAPbI_3 film into the O-face of ZnO single crystal is faster and more effective than that to Zn-face. It is supposed that O-face is more suitable for ZnO single crystal based perovskite cell fabrication than Zn-face.
文摘The phase diagram of the CsBr-CaBr2 system was re-determined by using differential thermal analysis and high ternperature and room ternperature X-ray diffraction analysis. It is concluded that there are three intermediate compounds in this system: a.congruently melting compound, CsCaBr3, with a melting point of 823℃ and two incongruently melting compounds, Cs2CaBr4 and Cs3Ca2Br7, whose peritectic points being 597℃ and 635℃, respectively. X-ray diffraction analysis indicated that compound CsCaBr3 is of slightly distorted perovskite structure.
基金supported by the National Natural Science Foundation of China (Nos. 20646002 and 20676061)
文摘La0.75Sr0.25CryMn1-yO3 (LSCM) (y = 0.0-0.6) composite oxides were synthesized by a complexing process of combining ethylene diamine tetraacetic acid (EDTA) and citrate. X-ray diffraction (XRD), temperature-programmed reduction, electrical conductivity, I-V polarization, and impedance spectroscopy were conducted to investigate the Cr doping effect of La0.75Sr0.25MnO3 on its phase stability and electrochemical performance as a solid-oxide fuel cell (SOFC) anode. The chemical and structural stabilities of the oxides increased steadily with increasing Cr doping concentration, while the electrical conductivity decreased on the contrary. At y 〉 0.4, the basic perovskite structure under the anode operating condition was sustained. A cell with 0.5-ram-thick scandia-stabilized zirconia electrolyte and La0.75Sr0.25CryMn1-yO3 anode delivered a Dower density of -15 mW-cm^-2 at 850℃.
基金Supported by the Science and Technology Development Planning of Jilin Province, China(Nos.20100116, 201105005)the Specialized Research Fund for the Doctoral Program(SRFDP) of Higher Education of China(No.20100061120089)+1 种基金the Open Project of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry of China (No.2011-01)the Open Project of State Key Laboratory of Superhard Materials of China(No.2011-04)
文摘The perovskite-type AgTaO3 crystals were prepared by mild hydrothermal method and determined by powder X-ray diffraction. Rietveld refinement indicates that AgTaO3 crystallized in an orthorhombic system with the space group Pcmn. The lattice parameters are a=5.5822(1) nm, b=7.8522(2) nm and c=5.5347(1) nm, with α=β=γ= 90.0o. The compound was characterized by scanning electron microscopy(SEM), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy(HR-TEM) and UV-Vis diffuse reflectance spectrometry (UV-Vis DRS). The photocatalytic activity of AgTaO3 powder was evaluated by the degradation of Congo red under UV-light irradiation. The result shows that the titled compound has a high photocatalytic activity at room temperature and potential application in photocatalysis.
文摘The organometal halide perovskite materials have a blend of surprising optoelectronic properties, for example high value of absorption coefficient and abrupt optical retention edge, lifetime, long charge carrier diffusion length and many more. Brought in conjunction with the capacity for manufacturing at low temperature, likewise from the solution, devices based on perovskite, particularly solar cells have been contemplated seriously with striking advancements in performance, in the course of recent years. The amalgamation of minimal effort, high efficiency and extra applications gives incredible potential to commercialization of these cells. The applications and performance of perovskite cells frequently relate with the structures of the device. Numerous creative structures of the devices were produced, targeting for vast scale manufacture, diminishing creation cost, upgrading the PCE and subsequently expanding the prospective for future applications. This paper outlines the various advanced structures of PSC, challenges confronted by these PSCs and their future perspectives. The commercial applications of PSC are additionally talked about in this paper.
文摘Nominal composition of Ca1-xZnxTiO3 : 0. 002Pr^3 + (x = 0. 000 - 0. 200) phosphors were prepared by conventional solid reaction route. XRD and PL measurements were used to investigate the solid-solution structure and luminescence properties of Zn-doped Ca1-xZnxTiO3:0.002Pr^3+ phosphors. The effect of solid-solution structure formed by substitution between Ca^2 + and Zn^2+ ions on the luminescent properties was analyzed. The results reveal that, with the increase of Zn substitution content below 0.010, lattice parameters and the intensity of excitation peak at both 260 and 330 nm as well as the corresponding 610 nm emission intensity are monotonously decreased quickly in a similar tendency. Also, the evolution of luminescence intensity and crystal cell parameters against Zn doping concentration are in good agreement. Above results are closely related with the structure change within Ca1- xZnxTiO3:0.002Pr^3+ solid-solution phase formed by the Zn ions substitution for the Ca sites. Present study reveals that the solid-solution structure formed by substitution between Ca^2+ and Zn^2+ ions has significant effect on the luminescence properties of single phase Ca1-xZnxTiO3:0.002Pr^3+ phosphors.
文摘Structure model of charge-ordered La_0.33 Ca_0.67 MnO_3, perovskite is one of current focused study in condensed matter physics. There are great discrepancies in previous studies in this field. Our transmission electron microscopy study confirms Wigner crystal model with transverse displacement and is not consisent with the hi-stripe model with longitudinal displacement. We observed incommensurate modulation and anti-phase domains with a displacement vector a_co/3 in charge--ordered La_0.33 Ca_0.67 MnO_3, perovskite.
基金FundedbytheNationalNaturalScienceFoundationofChi na (No .5 0 0 0 2 0 0 7) MajorProgramofMinistryofEducation (No.0 2 0 1)andOpenFoundationofStateKeyLabofAdvancedTech .forMaterialsSynthesisandProcessing.
文摘A n-Hexyl NH 3Sr 2Nb 3O 10 is obtained by the stepwise ion-exchange reaction,then is dispersed in aqueous solution of trinuclear acetato-hydroxo iron(III) nitrate,[Fe 3(OCOCH 3) 7OH·2H 2O]NO 3,and the interlayer potassium cations of the perovskite niobate are exchanged with the partially hydrolyzed trinuclear acetato complex ions.On heating,the exchanged complex ions are converted into iron oxide pillars which keep the perovskite sheets apart.The product is characterized by XRD,SEM,EDAX and surface area measurement respectively.
基金Supported by the program for National Natural Science Foundation of China(51102150,51472081)Foundation of Hubei University of Technology for High-level Talents(GCRC13014)Development Founds of Hubei Collaborative Innovation Center(HBSKFZD2014003,HBSKFZD2014011,HBSKFZD2015004)
文摘The effect of the distribution of organic cations CH3NH3^+(MA^+) on the stability,electronic structures and optical properties of CH3NH3 Pb I3 perovskite have been investigated using the plane-wave ultrasoft pseuudopotentials. Generalized gradient approximation and local density approximation are used to optimize the geometries of six models, which are different in the orientation of organic cations. The results show that model C is more stable than others, and the main contribution to the top of valence band is from I 5p states. In the bottom of conduction bands, the main components are Pb 6s states with an overlapping of I 5p states. When the orientation of organic group is transforming, the Pb I6 octahedra will distort and the band structure will alter with it, which affect the generation and migration of photon-generated carriers and optical properties.
基金Funded by the National Natural Science Foundation of China(No.51502179)the Colleges and Universities in Hebei Province Science and Technology Research Project(No.YQ2014033)the Hebei Key Discipline Construction Project(B2012210004 and E2013210038)
文摘We present the specific ab-initio calculations that detail the variations of perovskite BaZrO3 caused by in-plane strain. Specifically, the internal relaxation, which was not captured in the widely used biaxial strain model, was included in a complementary manner to lattice relaxation. Density functional theory as well as a hybrid functional method based on a plane wave basis set was employed to calculate the lattice structure, elastic constants, electronic properties and optical properties of perovskite BaZrO3. The lattice parameter c exhibited a clear linear dependence on the imposed in-plane strain, but the Poisson's ratio caused by internal relaxation was smaller than the elastic deformation, indicating an "inelastic" or "plastic" relaxation manner caused by the introduction of internal relaxation. As a result, the related electronic and optical properties of perovskite BaZrO3 were also strongly affected by the in-plane strain, which revealed an effective way to adjust the properties of perovskite BaZrO3 via internal relaxation.
基金Project supported by the National Natural Science Foundation of China (22171101)。
文摘A new series of multiferroic In_(1-x)Yb_(x)FeO_(3)(x=0.1,0.2,0.3) compounds were prepared using the traditional synthesis method for the first time.Partially substituting In ions in InFeO3with Yb ions results in the weak ferroelectricity of the compound.A dielectric relaxation peak is found at ~500 K in the temperature dependence of the dielectric properties of the resulted compounds.The dielectric constant of In_(0.8)Yb_(0.2)FeO_(3)displays an anomaly at -500 K,and the ferroelectric hysteresis loop reveals its weak ferroelectric behaviors below this temperature.Similarly to InFeO_(3),the compounds crystallize in space group P63/mmc.The increase in the Yb content leads to an increment in a and a reduction in c parameters.The temperature dependence of magnetization for In_(0.8)Yb_(0.2)FeO_(3)gives a Néel temperature of -150 K.The hysteresis loops at 10 and 100 K indicate its weak ferromagnetic characteristics above room temperature.Thus,In_(1-x)Yb_(x)FeO_(3)(x=0.1,0.2,0.3) compounds show both weak ferroelectricity and weak ferromagnetism.The non-symmetry of Yb cations causes the ferroelectricity of the compounds.
基金supported by State Grid Corporation of China Co.,Ltd.(Grant No.5500-202024252A-0-0-00).
文摘MnO_(2)-modified Pb_(0.9625)Sm_(0.025)(Mg_(1/3)Nb_(2/3))_(0.71)Ti_(0.2)9O_(3) ceramics were prepared via a solid-state reaction approach.Results of detailed characterizations revealed that the addition of MnO_(2) has influence on the grain size,and all samples exhibit a pure perovskite structure.As the content of manganese increases,the volume of tetragonal phase increases.The ceramics with 1.5 mol.%MnO_(2) show a high electro-strain of 0.151%at 2 kV/mm.Therefore,this study provides a new insight into the role of MnO_(2) addition in tailoring the electrical properties of the Sm-PMN-PT ceramics by acceptor doping.
基金Research was financially supported by the Ministry of Science and Higher Education of the Russian Federation(State assignment in the field of scientific activity,Southern Federal University,2020).
文摘The experimental and calculated data on the existence of complex oxides in solid state with the octahedral structures of four families,namely perovskites,Bi-containing layered perovskite-like ones,tetragonal tungsten bronzes and pyrochlores,and about their phase transitions are systematized and summarized on the basis of the quasi-elastic or geometric models of these structures.It has been established that similar existence areas and similar correlations between the interatomic bond strains in their structures,on the one hand,and the temperatures of their ferroelectric or antiferroelectric phase transitions,on the other hand,are observed for all of them,despite the differences in the compositions and structures of these oxides,but taking into account their similar parameters.
基金the financial support from the National Natural Science Foundation of China(Grant Nos.11674161,11174122 and 11134004)the Six Big Talent Peak Project from Jiangsu Province(Grant No.XCL-004)open project of National Laboratory of Solid State Microstructures,Nanjing University(Grant No.M28026)
文摘Molten salt synthesis (MSS) method has advantages of the simplicity in the process equipment, versatile and large-scale synthesis, and friendly environment, which provides an excellent approach to synthesize high pure oxide powders with controllable compositions and morphologies. Among these oxides, perovskite oxides with a composition of ABO3 exhibit a broad spectrum of physical properties and functions (e.g. ferroelectric, piezoelectric, magnetic, photovoltaic and photocatalytic properties). The downscaling of the spatial geometry of perovskite oxides into nanometers result in novel properties that are different from the bulk and film counterparts. Recent interest in nanoscience and nanotechnology has led to great efforts focusing on the synthesis of low-dimensional perovskite oxide nanostructures (PONs) to better understand their novel physical properties at nanoscale. Therefore, the low-dimensional PONs such as perovskite nanoparticles, nanowires, nanorods, nanotubes, nanofibers, nanobelts, and two dimensional oxide nanostructures, play an important role in developing the next generation of oxide electronics. In the past few years, much effort has been made on the synthesis of PONs by MSS method and their structural characterizations. The functional applications of PONs are also explored in the fields of storage memory, energy harvesting, and solar energy conversion. This review summarizes the recent progress in the synthesis of low-dimensional PONs by MSS method and its modified ways. Their structural char- acterization and physical properties are also scrutinized. The potential applications of low-dimensional PONs in different fields such as data memory and storage, energy harvesting, solar energy conversion, are highlighted. Perspectives concerning the future research trends and challenges of low-dimensional PONs are also outlined. ~ 2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.