Combining microwave radiation with photocatalytic systems is a promising method to inhibit photogenerated electron-hole recombination and enhance the photocatalytic reaction performance. In this study, we have designe...Combining microwave radiation with photocatalytic systems is a promising method to inhibit photogenerated electron-hole recombination and enhance the photocatalytic reaction performance. In this study, we have designed Pd/Pb TiO3 catalysts that can use both microwave fields and photocatalysis. Benefiting from the synergistic effect of microwave field and UV light, the Pb TiO3 crystals convert thermal energy into electrical energy via the pyroelectricity effect, generating positive and negative charges(q+ and q-), while Pd nanoparticles significantly improve the quantum efficiency of the photocatalytic process. The composite catalyst significantly enhances the reaction rate and selectivity of the model Suzuki coupling reaction performed with bromobenzene. Microwave fields can directly act on chemical systems, promoting or changing various chemical reactions in unique ways.展开更多
In pyroelectric materials there is a spontaneous dielectric polarization.When raising the temperature,then a voltage appears in the system.In the present manuscript a phenomenological theory of pyroelectricity is deve...In pyroelectric materials there is a spontaneous dielectric polarization.When raising the temperature,then a voltage appears in the system.In the present manuscript a phenomenological theory of pyroelectricity is developed.展开更多
Ferroelectric materials are ideal for self-powered sensors in Internet of Things(IoT)and high-precision detection systems due to their excellent polarization properties.Compatibility with miniaturization,high-density ...Ferroelectric materials are ideal for self-powered sensors in Internet of Things(IoT)and high-precision detection systems due to their excellent polarization properties.Compatibility with miniaturization,high-density systems,and complementary metal oxide semiconductor(CMOS)processes is crucial for their widespread adoption.HfO_(2)-based ferroelectricfilms show potential in self-powered pyroelectric sensors as their thinness enables effective temperature and light detection.However,the disordered ferroelectric domain distribution limits their pyroelectric performance and hampers the development of highly integrated self-powered pyroelectric devices.This report investigates the temperature and light detection capabilities of Ce-doped HfO_(2)ferroelectricfilms,which exhibit as-grown spontaneous polarization in the downward direction,making them a promising option for self-powered pyroelectric sensors.Thefindings provide robust evidence that the introduction of a temperature gradient significantly enhances pyroelectricity.In addition,their applications in the detection of hot/cold wind and breathing have been proved.Notably,the 30 nm thick Ce-doped HfO_(2)ferroelectricfilm has a high pyroelectric coefficient of about 894.7μC·m^(-2)·K^(-1)and enables high-precision detection of changes in temperature of 0.1 K.This study highlights the potential application of HfO_(2)-based ferroelectricfilms in self-powered sensors with temperature and light detection capabilities,making them a promising candidate for future IoT-based systems and high-precision detection systems.展开更多
The typical wastewater treatment is focused on the photocatalytic efficiency in the degradation of organic pollutants,with little attention to the involved selectivity which may correlate with toxicant residues.Herein...The typical wastewater treatment is focused on the photocatalytic efficiency in the degradation of organic pollutants,with little attention to the involved selectivity which may correlate with toxicant residues.Herein,an electron localization strategy for specific O2 adsorption/activation enabled by photothermal/pyroelectric effect and in situ constructed active centers of single-atom Co and oxygen vacancy(Co-O_(V))on the Co/BiOCl-O_(V)photocatalyst was developed for photocatalytic degradation of glyphosate(GLP)wastewater of high performance/selectivity.Under full-spectrum-light irradiation,a high GLP degradation rate of 99.8%with over 90%C-P bond-breaking selectivity was achieved within 2 h,while effectively circumventing toxicant residues such as aminomethylphosphonic acid(AMPA).X-ray absorption spectroscopy and relevant characterizations expounded the tailored anchoring of Co single atoms onto the BiOCl-O_(V)carrier and photothermal/pyroelectric effect.The oriented formation of more•O_(2)^(−)on Co/BiOCl-O_(V)could be achieved with the Co-O_(V)coupled center that had excellent O2 adsorption/activation capacity,as demonstrated by quantum calculations.The formed unique Co-O_(V)active sites could largely decrease the C-P bond-breaking energy barrier,thus greatly improving the selectivity toward the initial C-P bond scission and the activity in subsequent conversion steps in the directional photocatalytic degradation of GLP.The electron localization strategy by in situ constructing the coupled active centers provides an efficient scheme and new insights for the low-toxic photodegradation of organic pollutants containing C-X bonds.展开更多
Photocatalytic transformation of biomass into biofuels and value-added chemicals is of great significance for carbon neutrality.Metal-free carbon nitride has extensive applications but with almost no absorption and ut...Photocatalytic transformation of biomass into biofuels and value-added chemicals is of great significance for carbon neutrality.Metal-free carbon nitride has extensive applications but with almost no absorption and utilization of near-infrared light,accounting for 50%of sunlight.Here,a molten salt-assisted in-plane“stitching”and interlayer“cutting”protocol is developed for constructing a highly crystalline carbon nitride catalyst containing structural oxygen(HC-CN).HC-CN is highly efficient for the photothermal cascade transformation of biomass-derived glucose into lactic acid(LA)with an unprecedented yield(94.3%)at 25°C under full-spectrum light irradiation within 50 min,which is also applicable to quantitatively photo-upgrading various saccharides.Theoretical calculations expound that the light-induced glucose-to-catalyst charge transfer can activate the Cβ-H bond to promote the rate-determining step of intramolecular hydrogen shift in glucose-to-fructose isomerization.Meanwhile,the introduced structural oxygen in HC-CN can not only facilitate the local electric field formation to achieve rapid charge transport/separation and regulate selective·O^(-)_(2)generation for oriented C3-C4 bond cleavage of fructose but also narrow the energy band gap to broaden the light absorption range of HC-CN,contributing to enhanced LA production without exogenous heating.Moreover,HC-CN is highly recyclable and exhibits negligible environmental burden and low energy consumption,as disclosed by the life cycle assessment.Tailored construction of full-spectrum light adsorption and versatile reaction sites provides a reference for implementing multi-step biomass and organic conversion processes under mild conditions.展开更多
Pyroelectric materials, known for their ability to convert thermal energy into electrical signals, have garnered significant attention due to their wide-ranging applications. In this work, we report the fabrication of...Pyroelectric materials, known for their ability to convert thermal energy into electrical signals, have garnered significant attention due to their wide-ranging applications. In this work, we report the fabrication of high-performance pyroelectric photodetectors utilizing a heterostructure of carbon nanotube film(CNTF) and silver nanostructure film(Ag NSF)on a lead zirconate titanate(PZT) substrate. The resulting device exhibits an impressive broad-spectrum photoelectric response, covering wavelengths from ultraviolet to near-infrared, with a responsivity range of 0.49 V·W^(-1)–1.01 V·W^(-1) and a fast response time of 8 ms–40 ms. The enhanced photoelectric properties of the CNTF/Ag NSF/PZT composite suggest its strong potential for applications in advanced broadband photodetectors, positioning this material system as a promising candidate for next-generation optoelectronic devices.展开更多
In dynamic problems the electric and magnetic fields are inseparable. At the same time, a multitude of electrostatic and magnetostatic effects permit mutually independent description. This separation appears to be pos...In dynamic problems the electric and magnetic fields are inseparable. At the same time, a multitude of electrostatic and magnetostatic effects permit mutually independent description. This separation appears to be possible and thermodynamically consistent when the bulk energy density depends only on the polarization density or, alternatively, on the magnetization density. However, when the bulk energy density depends simultaneously on the both densities, then, the electrostatic and magnetostatic effects should be studied together. There appear interesting cross-effects;among those are the change of the internal electrostatic field inside a specimen under the influence of the external magnetic fields, and vice versa. Below, in the framework of thermodynamic approach the boundary value problem for magnetoelectric plate is formulated and analyzed. The exact solution is established for the isotropic pyroelectric plate.展开更多
The pyroelectric medium is an important material in the application of smart materials and structures. It is necessary to systematically discuss ail kinds of variational principles which play a very significant role i...The pyroelectric medium is an important material in the application of smart materials and structures. It is necessary to systematically discuss ail kinds of variational principles which play a very significant role in the fundamental theory of mechanics and numerical analysis method. This paper firstly gives the quasi-static and the dynamic variational principles,then the principles for eigen problems. As a simple example, the principle was finally applied to derive the fundamental, equations for an anisotropic piezoelectric plate.展开更多
Single-crystal X-ray diffraction structural data of four Fe-Mg tourmalines with different Fe contents from Xinjiang, Sichuan, and Yunnan Provinces, China, were collected at room temperature and-100oC. The intrinsic di...Single-crystal X-ray diffraction structural data of four Fe-Mg tourmalines with different Fe contents from Xinjiang, Sichuan, and Yunnan Provinces, China, were collected at room temperature and-100oC. The intrinsic dipole moments of polyhedra and the total intrinsic dipole moment of the unit cell were calculated. By comparing the intrinsic electric dipole moments of the X, Y, Z, T, and B site polyhedra, it is found that the T site polyhedron makes the greatest contribution to the total intrinsic dipole moment. The pyroelectric coefficients of four Fe-Mg tourmalines were experimentally determined, and the influence of intrinsic dipole moments on their pyroelectric properties was inves-tigated. The experimental results show that, compared with the case at room temperature, the intrinsic dipole moments change with the total Fe content at-100oC in a completely different way. With the decrease of temperature, the total intrinsic dipole moments of tourmaline de-crease. Over the same temperature interval, the pyroelectric coefficients increase with the increase in intrinsic dipole moment.展开更多
Large pyroelectric and energy harvesting properties have been attracting increasing attentions due to the practical applications in infrared detectors and energy harvesting technologies.Ferroelectricantiferroelectric(...Large pyroelectric and energy harvesting properties have been attracting increasing attentions due to the practical applications in infrared detectors and energy harvesting technologies.Ferroelectricantiferroelectric(FE-AFE)phase transitions are usually accompanied by a sharp drop in polarization,which will lead to excellent pyroelectric properties and energy harvesting density.Therefore,FE-AFE phase boundary design is an effective strategy to develop new pyroelectric materials.In this paper,Pb(Lu_(1/2)Nb_(1/2))O_(3)-PbTiO_(3) (PLN-PT)single crystals with FE-AFE phase transitions were obtained by molten salt growth method.The temperature-induced FE-AFE phase transition was verified by temperaturedependent macrodomain structure,DSC curves and dielectric properties.Obviously,PLN-PT crystals display excellent peak pyroelectric coefficient(~6.8μC/(cm^(2)·K)with a maximum depolarization temperature of 118℃.Meanwhile,the pyroelectric energy harvesting density is as high as 2.62 J/cm3,which is much higher than other pyroelectric materials.The results reveal that the PLN-PT crystal is a promising candidate for infrared detectors and energy harvesting devices.展开更多
Previously, synthetic hexagonal bismuth sulfide iodide (polar space group P63, a = 15.629(3) ?, c = 4.018(1) ?, Z = 2) has been described by the rather unsatisfactory fractional formula Bi19/3IS9 [1] 08D0C9EA79F9BACE1...Previously, synthetic hexagonal bismuth sulfide iodide (polar space group P63, a = 15.629(3) ?, c = 4.018(1) ?, Z = 2) has been described by the rather unsatisfactory fractional formula Bi19/3IS9 [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400310037003600350038003400370039000000 -[3] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400310037003600350038003400370036000000 . A redetermination of the structure using old but reliable photographic intensity data indicated the presence of additional split positions and reduced atomic occupancies. From the observed pattern of this “averaged” structure a consistent model of a superstructure with lattice parameters of a' = √13·a = 56.35(1) ?, c' = c, and a formula Bi5-x(Bi2S3)39I12S emerged, with 2 formula units in a cell of likewise P63 space group. Structural modulation may be provoked by the space the lone electron pair of Bi requires. When Bi on the 0, 0, z position of the “averaged” cell is transferred to two general six-fold sites and one unoccupied twofold one of the super-cell, more structural stability is guaranteed due to compensation of its basal plane dipole momentum. Owing to the limited intensity data available, more details of the superstructure are not accessible yet. Some physical properties and solar cell application are discussed together with suggestions of ambient temperature synthesis routes of c-axis oriented nano-rod sheets.展开更多
Using the same conditions and various starting materials, such as lead acetate trihydrate, tetrabulyl titanate, zirconium n-butoxide, and acetylacetone, two kinds of solid precursors, lead zirconate titanate （PZT, Zr...Using the same conditions and various starting materials, such as lead acetate trihydrate, tetrabulyl titanate, zirconium n-butoxide, and acetylacetone, two kinds of solid precursors, lead zirconate titanate （PZT, Zr/Ti=15/85） and lead titanate （PT）, were fabricated. With three different combinations, namely, PZT, PT/PZT-PZT/PT, and PT/PZT/-/PZT/PT, three multilayer thin films were deposited on three Pt-Ti-Si3N4-SiO2-Si substrates by a modified sol-gel process. The fabrication process of the thin films is discussed in detail. We found that there is a large built-in stress in the thin film, which can be diminished by annealing at 600 ℃, when the gel is turned into solid material through drying and sintering. The Raman scattering spectra of the films with different compositions and structures were investigated. With the help of X-ray diffraction （XRD） analyzer and Raman scattering spectra analyzer, it was found that the thin films with the PT/PZT-PZT/PT structure have reasonable crystallinity and less residual stress. XRD testing shows that the diffraction pattern of the multilayer film results from the superimposition of the PZT and PT patterns. This leads to the conclusion that the PT/PZT-PZT/PT multilayer thin film has a promising future in pyroelectric infrared detectors with high performance.展开更多
TGS (triglycine sulfate) is a pyroelectric crystal material which has an excllent pyroelectricity.The LATGS,a kind of doped TGS crystal,in which L α alanine (LA) substitues for glycine partially and induces an intern...TGS (triglycine sulfate) is a pyroelectric crystal material which has an excllent pyroelectricity.The LATGS,a kind of doped TGS crystal,in which L α alanine (LA) substitues for glycine partially and induces an internal bias in TGS resulting in permanently poled single domain crystal,becomes the comprehensively used pyroelectric material. Based on the study which was about the locked polarization in LATGS,we select many kinds of aminoacids which have a strong polarity group and a unsymmetry atom to dope into TGS crystals.The aninoacids are LB (L asparagine),LL (L lysine),LH (L histidine) and LG (L glutamid acid).The saturated solutions for above four crystals growth are prepared by TGS doped with different aminoacids in water. Transparent crystals up to several centinetres in size have been grown by circling plate method and the reversible rotation rate of the platform with the crystal was about 90 r/min.There was a prefered growth in the b axis direction,with a growth rate of the b axis of about 1.0-1.2mm/day.The concentrations of aminoacids doped in TGS crystals were determined by a liquid chromatography,the concentrations of different aminoacids are about 10 -3 . It shows that the lattice parameters ( a,b and V )of TGS doped with aminoacids are significant longer than that of pure TGS crystal. We conclude that the pyroelectic cofficient,pyroelectric merit and the locked polarization of four TGS crystals,especially,the internal bield ( E b ) of LLTGS is larger than the LATGS,so that the LLTGS crystal is a promising pyroelectrc material for infrared detector.展开更多
By studying both the microscopic physical and chemical typomorphic characteristics of typical mineral pyrite samples associated with representative gold deposits on the north-central margin of the North China Platform...By studying both the microscopic physical and chemical typomorphic characteristics of typical mineral pyrite samples associated with representative gold deposits on the north-central margin of the North China Platform,this paper seeks to identify macroscopic metallogenic mechanisms of gold deposits and to reveal the formation mechanism of lattice gold in pyrite.Typomorphic characteristics of pyrite reveal that pyrite grain size has a negative correlation with gold content.Cubic pyrite,as the dominant crystal form,contains more gold than pentagonal dodecahedral pyrite.Both pyrite crystal forms and chemical compositions indicate that the replacement style of gold deposit formed in a low saturability,low sulfur fugacity,and at temperatures either much higher or much lower than its best forming temperature;comparatively,that of the quartz vein style of gold deposit occurred under conditions with the best temperature,rich in sulfur,and with high sulfur fugacity.The Au/Ag ratios of the pyrites show that both the replacement and quartz vein styles of deposits are mesothermal and hypothermal,while the Co/Ni ratios of the pyrites indicate that the quartz vein style is of magmatic-hydrothermal origin.The X-ray diffraction intensity of pyrite rich in gold is lower than that of pyrite poor in gold at the quartz vein style.In general,with an increase in gold content in pyrite,the total sum intensityΣI decreases.The pyroelectricity coefficient has a negative correlation trend with the values of(Co+Ni+Se+Te)-As and(Co+Ni+Se+Te)/As.The pyrite pyroelectricity of the replacement style is N-type,indicating that it formed under low sulfur fugacity,while that of the quartz vein style is a mixture of P-N types,indicating that it formed under high sulfur fugacity.On the pyroelectricity-temperature diagram,pyrite of the replacement style is mainly distributed between 200 and 270°C,while that of the quartz vein style varies between 90–118 and274–386°C,demonstrating a multistage forming process.In contrast to previous researchers'conclusions,the authors confirm the existence of lattice gold in pyrites through the use of an electron paramagnetic resonance(EPR)test.Au in the form of Au~+,entering pyrite as an isomorph and producing electron–hole centers,makes the centers produce spin resonance absorption and results in EPR absorption peak II.The intensity of auriferous pyrite absorption peak II has certain direct positive correlations with pyrite gold content.The#I and#III absorption peaks of pyrites possibly result from the existence of Ni^(2+)and/or Cu^(2+).γ1,γ2,andγ3 are the strongest and most typical absorption peaks of the infrared spectra of the pyrites.Generally,with the increase in gold content in the pyrite samples,γ1,γ2,andγ3 tend to shift to higher wavenumbers,and the gold content in the pyrite samples has a positive correlation with their relative absorbance.展开更多
Located at the boundary of Chongli county, Chicheng county and Xuanhua county of Heibei province, the Dongping gold deposit is genetically affiliated to the late Jurassic- early Cretaceous volcanics and intrusives. Th...Located at the boundary of Chongli county, Chicheng county and Xuanhua county of Heibei province, the Dongping gold deposit is genetically affiliated to the late Jurassic- early Cretaceous volcanics and intrusives. The ore body is quartz vein- and alteration-type and pyrite and quartz are the dominant gold-bearing minerals.展开更多
National parks are highly valuable natural areas and have the potential to attract a large number of visitors.The number of visitors at national parks is systematically increasing,often exceeding Tourism Carrying Capa...National parks are highly valuable natural areas and have the potential to attract a large number of visitors.The number of visitors at national parks is systematically increasing,often exceeding Tourism Carrying Capacity(TCC)of trails.This situation requires adjusting the number of park visitors to adapt to sustainable management systems of visitor flow,thus preventing or counteracting overtourism.The aim of the study is to propose a comprehensive method for tourists monitoring in mid-mountain national park presented on the example of the Sto?owe Mountains National Park(SMNP)in Poland,called as Monitoring System of tourist traffic(MSTT).The study describes six stages procedure of tourists Monitoring System creation and application as an optimal measurement technique.The MSTT enabled a multidimensional analysis of tourist traffic in SMNP.With the help of 39 pyroelectric sensors and surveys data spatio-temporal characteristic of visitor flow was obtained.The data generated in MSTT included hourly,daily,weekly,monthly,and annual reports,taking into account the direction of traffic measuring both directions:entries(IN),exits(OUT)and passages(IN+OUT).The results from pyroelectric sensors were supplemented with field surveys,where visitor’s motivations,preferences,and behaviours were determined.In 2017 a total of 871,344 visitors were recorded in SMNP what causes one of the most popular national parks in Poland.The SMNP is a suitable destination for short breaks leisure visits in wilderness.In order to sustain MSTT methodology in the long-run the set of guidelines together with the workload estimates were presented.In the future,the MSTT can be further developed,including monitoring of climbing,cycling,cross-country skiing,car traffic and illegal tourism assessment.The MSTT can be considered as a useful tool for tourism management in mid-mountain national parks throughout the entire calendar year.展开更多
Understanding the bioelectrical properties of bone tissue is key to developing new treatment strategies for bone diseases and injuries,as well as improving the design and fabrication of scaffold implants for bone tiss...Understanding the bioelectrical properties of bone tissue is key to developing new treatment strategies for bone diseases and injuries,as well as improving the design and fabrication of scaffold implants for bone tissue engineering.The bioelectrical properties of bone tissue can be attributed to the interaction of its various cell lineages(osteocyte,osteoblast and osteoclast)with the surrounding extracellular matrix,in the presence of various biomechanical stimuli arising from routine physical activities;and is best described as a combination and overlap of dielectric,piezoelectric,pyroelectric and ferroelectric properties,together with streaming potential and electro-osmosis.There is close interdependence and interaction of the various electroactive and electrosensitive components of bone tissue,including cell membrane potential,voltage-gated ion channels,intracellular signaling pathways,and cell surface receptors,together with various matrix components such as collagen,hydroxyapatite,proteoglycans and glycosaminoglycans.It is the remarkably complex web of interactive cross-talk between the organic and non-organic components of bone that define its electrophysiological properties,which in turn exerts a profound influence on its metabolism,homeostasis and regeneration in health and disease.This has spurred increasing interest in application of electroactive scaffolds in bone tissue engineering,to recapitulate the natural electrophysiological microenvironment of healthy bone tissue to facilitate bone defect repair.展开更多
MnO_2doped PbTiO_3 ceramics was prepared by means of solgel method, its density and some electric properties were investigated. The results showed that it was feasible to prepare multicomponent PbTiO_3 solgel series ...MnO_2doped PbTiO_3 ceramics was prepared by means of solgel method, its density and some electric properties were investigated. The results showed that it was feasible to prepare multicomponent PbTiO_3 solgel series with the aid of solgel method, the obtained MnO_2doped PbTiO_3 ceramics showed a highpurity, uniform component, better dense structure, hardly crack, and had good dielectric, piezoelectric, ferroelectric and pyroelectric properties.展开更多
This paper investigates the pyroelectric of poled antiferroelectric （AFE） ceramic Pbo.97Lao.02 （Zro.69Sno.196 Ti0.114）03 and its remnant polarization dependence of hydrostatic pressure. The results show that the b...This paper investigates the pyroelectric of poled antiferroelectric （AFE） ceramic Pbo.97Lao.02 （Zro.69Sno.196 Ti0.114）03 and its remnant polarization dependence of hydrostatic pressure. The results show that the bound charges of poled sample can be released in short time by temperature field or pressure field. The released charge abruptly forms a large pulse current. The phenomena of released charge under external fields result in the ferroelectric-AFE phase transition induced by temperature or hydrostatic pressure.展开更多
A finite element approach based on the micromechanics was performed to estimate the multi-field properties of electro-magneto-thermoelastic composites. The thermal field and the involved pyroelectric and pyromagnetic ...A finite element approach based on the micromechanics was performed to estimate the multi-field properties of electro-magneto-thermoelastic composites. The thermal field and the involved pyroelectric and pyromagnetic effect of the multi-phase composite materials were taken into account in the investigation and implemented in the finite element modeling. The multi- fields related to the electric field, magnetic field, deformation and temperature field, as well as their coupling effects of the smart composites under periodic boundary conditions were obtained numerically. Especially, by means of the homogenization approximation, the effective thermal ex- pansion coefficients, pyroelectric coefficients, pyromagnetic coefficients and other elastic, electric, and magnetic properties for the piezoelectric material, piezomagnetic material and magnetoelec- tric material were calculated, respectively. Some results are compared to the theoretical predictions by the well-known Mori-Tanaka method to show good agreements.展开更多
文摘Combining microwave radiation with photocatalytic systems is a promising method to inhibit photogenerated electron-hole recombination and enhance the photocatalytic reaction performance. In this study, we have designed Pd/Pb TiO3 catalysts that can use both microwave fields and photocatalysis. Benefiting from the synergistic effect of microwave field and UV light, the Pb TiO3 crystals convert thermal energy into electrical energy via the pyroelectricity effect, generating positive and negative charges(q+ and q-), while Pd nanoparticles significantly improve the quantum efficiency of the photocatalytic process. The composite catalyst significantly enhances the reaction rate and selectivity of the model Suzuki coupling reaction performed with bromobenzene. Microwave fields can directly act on chemical systems, promoting or changing various chemical reactions in unique ways.
文摘In pyroelectric materials there is a spontaneous dielectric polarization.When raising the temperature,then a voltage appears in the system.In the present manuscript a phenomenological theory of pyroelectricity is developed.
基金the National Natural Science Foundation of China(Grant No.12175191)the Science and Technology Innovation Program of Hunan Province,China(Grant No.2023RC3134)+1 种基金the Natural Science Foundation of Hunan Province,China(Grant No.2022JJ30566)the Research Foundation of Education Bureau of Hunan Province,China(Grant No.22A0134).
文摘Ferroelectric materials are ideal for self-powered sensors in Internet of Things(IoT)and high-precision detection systems due to their excellent polarization properties.Compatibility with miniaturization,high-density systems,and complementary metal oxide semiconductor(CMOS)processes is crucial for their widespread adoption.HfO_(2)-based ferroelectricfilms show potential in self-powered pyroelectric sensors as their thinness enables effective temperature and light detection.However,the disordered ferroelectric domain distribution limits their pyroelectric performance and hampers the development of highly integrated self-powered pyroelectric devices.This report investigates the temperature and light detection capabilities of Ce-doped HfO_(2)ferroelectricfilms,which exhibit as-grown spontaneous polarization in the downward direction,making them a promising option for self-powered pyroelectric sensors.Thefindings provide robust evidence that the introduction of a temperature gradient significantly enhances pyroelectricity.In addition,their applications in the detection of hot/cold wind and breathing have been proved.Notably,the 30 nm thick Ce-doped HfO_(2)ferroelectricfilm has a high pyroelectric coefficient of about 894.7μC·m^(-2)·K^(-1)and enables high-precision detection of changes in temperature of 0.1 K.This study highlights the potential application of HfO_(2)-based ferroelectricfilms in self-powered sensors with temperature and light detection capabilities,making them a promising candidate for future IoT-based systems and high-precision detection systems.
基金supported by the National Natural Science Foundation of China(No.22368014)Guizhou Provincial S&T Project(Nos.GCC[2023]011,ZK[2022]011)Guizhou Provincial Higher Education Institution Program(No.Qianjiaoji[2023]082).
文摘The typical wastewater treatment is focused on the photocatalytic efficiency in the degradation of organic pollutants,with little attention to the involved selectivity which may correlate with toxicant residues.Herein,an electron localization strategy for specific O2 adsorption/activation enabled by photothermal/pyroelectric effect and in situ constructed active centers of single-atom Co and oxygen vacancy(Co-O_(V))on the Co/BiOCl-O_(V)photocatalyst was developed for photocatalytic degradation of glyphosate(GLP)wastewater of high performance/selectivity.Under full-spectrum-light irradiation,a high GLP degradation rate of 99.8%with over 90%C-P bond-breaking selectivity was achieved within 2 h,while effectively circumventing toxicant residues such as aminomethylphosphonic acid(AMPA).X-ray absorption spectroscopy and relevant characterizations expounded the tailored anchoring of Co single atoms onto the BiOCl-O_(V)carrier and photothermal/pyroelectric effect.The oriented formation of more•O_(2)^(−)on Co/BiOCl-O_(V)could be achieved with the Co-O_(V)coupled center that had excellent O2 adsorption/activation capacity,as demonstrated by quantum calculations.The formed unique Co-O_(V)active sites could largely decrease the C-P bond-breaking energy barrier,thus greatly improving the selectivity toward the initial C-P bond scission and the activity in subsequent conversion steps in the directional photocatalytic degradation of GLP.The electron localization strategy by in situ constructing the coupled active centers provides an efficient scheme and new insights for the low-toxic photodegradation of organic pollutants containing C-X bonds.
基金the Natural Science Foundation of China(22368014,22478087)the Guizhou Provincial S&T Project(GCC[2023]011,ZK[2022]011).
文摘Photocatalytic transformation of biomass into biofuels and value-added chemicals is of great significance for carbon neutrality.Metal-free carbon nitride has extensive applications but with almost no absorption and utilization of near-infrared light,accounting for 50%of sunlight.Here,a molten salt-assisted in-plane“stitching”and interlayer“cutting”protocol is developed for constructing a highly crystalline carbon nitride catalyst containing structural oxygen(HC-CN).HC-CN is highly efficient for the photothermal cascade transformation of biomass-derived glucose into lactic acid(LA)with an unprecedented yield(94.3%)at 25°C under full-spectrum light irradiation within 50 min,which is also applicable to quantitatively photo-upgrading various saccharides.Theoretical calculations expound that the light-induced glucose-to-catalyst charge transfer can activate the Cβ-H bond to promote the rate-determining step of intramolecular hydrogen shift in glucose-to-fructose isomerization.Meanwhile,the introduced structural oxygen in HC-CN can not only facilitate the local electric field formation to achieve rapid charge transport/separation and regulate selective·O^(-)_(2)generation for oriented C3-C4 bond cleavage of fructose but also narrow the energy band gap to broaden the light absorption range of HC-CN,contributing to enhanced LA production without exogenous heating.Moreover,HC-CN is highly recyclable and exhibits negligible environmental burden and low energy consumption,as disclosed by the life cycle assessment.Tailored construction of full-spectrum light adsorption and versatile reaction sites provides a reference for implementing multi-step biomass and organic conversion processes under mild conditions.
基金Project supported in part by the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics (Grant No. KF202007)the NSAF (Grant No. U1730246)。
文摘Pyroelectric materials, known for their ability to convert thermal energy into electrical signals, have garnered significant attention due to their wide-ranging applications. In this work, we report the fabrication of high-performance pyroelectric photodetectors utilizing a heterostructure of carbon nanotube film(CNTF) and silver nanostructure film(Ag NSF)on a lead zirconate titanate(PZT) substrate. The resulting device exhibits an impressive broad-spectrum photoelectric response, covering wavelengths from ultraviolet to near-infrared, with a responsivity range of 0.49 V·W^(-1)–1.01 V·W^(-1) and a fast response time of 8 ms–40 ms. The enhanced photoelectric properties of the CNTF/Ag NSF/PZT composite suggest its strong potential for applications in advanced broadband photodetectors, positioning this material system as a promising candidate for next-generation optoelectronic devices.
文摘In dynamic problems the electric and magnetic fields are inseparable. At the same time, a multitude of electrostatic and magnetostatic effects permit mutually independent description. This separation appears to be possible and thermodynamically consistent when the bulk energy density depends only on the polarization density or, alternatively, on the magnetization density. However, when the bulk energy density depends simultaneously on the both densities, then, the electrostatic and magnetostatic effects should be studied together. There appear interesting cross-effects;among those are the change of the internal electrostatic field inside a specimen under the influence of the external magnetic fields, and vice versa. Below, in the framework of thermodynamic approach the boundary value problem for magnetoelectric plate is formulated and analyzed. The exact solution is established for the isotropic pyroelectric plate.
基金The work is supported by the Doctoral Education Foundation.
文摘The pyroelectric medium is an important material in the application of smart materials and structures. It is necessary to systematically discuss ail kinds of variational principles which play a very significant role in the fundamental theory of mechanics and numerical analysis method. This paper firstly gives the quasi-static and the dynamic variational principles,then the principles for eigen problems. As a simple example, the principle was finally applied to derive the fundamental, equations for an anisotropic piezoelectric plate.
基金financially supported by the National Natural Science Foundation of China(No.40672031)
文摘Single-crystal X-ray diffraction structural data of four Fe-Mg tourmalines with different Fe contents from Xinjiang, Sichuan, and Yunnan Provinces, China, were collected at room temperature and-100oC. The intrinsic dipole moments of polyhedra and the total intrinsic dipole moment of the unit cell were calculated. By comparing the intrinsic electric dipole moments of the X, Y, Z, T, and B site polyhedra, it is found that the T site polyhedron makes the greatest contribution to the total intrinsic dipole moment. The pyroelectric coefficients of four Fe-Mg tourmalines were experimentally determined, and the influence of intrinsic dipole moments on their pyroelectric properties was inves-tigated. The experimental results show that, compared with the case at room temperature, the intrinsic dipole moments change with the total Fe content at-100oC in a completely different way. With the decrease of temperature, the total intrinsic dipole moments of tourmaline de-crease. Over the same temperature interval, the pyroelectric coefficients increase with the increase in intrinsic dipole moment.
基金Project supported by the National Natural Science Foundation of China(51902307,11904362,11974349)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB20000000)+1 种基金Youth Innovation Promotion Association CASScience and Technology Project of Fujian Province(2020H0038,2019H0052)。
文摘Large pyroelectric and energy harvesting properties have been attracting increasing attentions due to the practical applications in infrared detectors and energy harvesting technologies.Ferroelectricantiferroelectric(FE-AFE)phase transitions are usually accompanied by a sharp drop in polarization,which will lead to excellent pyroelectric properties and energy harvesting density.Therefore,FE-AFE phase boundary design is an effective strategy to develop new pyroelectric materials.In this paper,Pb(Lu_(1/2)Nb_(1/2))O_(3)-PbTiO_(3) (PLN-PT)single crystals with FE-AFE phase transitions were obtained by molten salt growth method.The temperature-induced FE-AFE phase transition was verified by temperaturedependent macrodomain structure,DSC curves and dielectric properties.Obviously,PLN-PT crystals display excellent peak pyroelectric coefficient(~6.8μC/(cm^(2)·K)with a maximum depolarization temperature of 118℃.Meanwhile,the pyroelectric energy harvesting density is as high as 2.62 J/cm3,which is much higher than other pyroelectric materials.The results reveal that the PLN-PT crystal is a promising candidate for infrared detectors and energy harvesting devices.
文摘Previously, synthetic hexagonal bismuth sulfide iodide (polar space group P63, a = 15.629(3) ?, c = 4.018(1) ?, Z = 2) has been described by the rather unsatisfactory fractional formula Bi19/3IS9 [1] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400310037003600350038003400370039000000 -[3] 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003400310037003600350038003400370036000000 . A redetermination of the structure using old but reliable photographic intensity data indicated the presence of additional split positions and reduced atomic occupancies. From the observed pattern of this “averaged” structure a consistent model of a superstructure with lattice parameters of a' = √13·a = 56.35(1) ?, c' = c, and a formula Bi5-x(Bi2S3)39I12S emerged, with 2 formula units in a cell of likewise P63 space group. Structural modulation may be provoked by the space the lone electron pair of Bi requires. When Bi on the 0, 0, z position of the “averaged” cell is transferred to two general six-fold sites and one unoccupied twofold one of the super-cell, more structural stability is guaranteed due to compensation of its basal plane dipole momentum. Owing to the limited intensity data available, more details of the superstructure are not accessible yet. Some physical properties and solar cell application are discussed together with suggestions of ambient temperature synthesis routes of c-axis oriented nano-rod sheets.
文摘Using the same conditions and various starting materials, such as lead acetate trihydrate, tetrabulyl titanate, zirconium n-butoxide, and acetylacetone, two kinds of solid precursors, lead zirconate titanate （PZT, Zr/Ti=15/85） and lead titanate （PT）, were fabricated. With three different combinations, namely, PZT, PT/PZT-PZT/PT, and PT/PZT/-/PZT/PT, three multilayer thin films were deposited on three Pt-Ti-Si3N4-SiO2-Si substrates by a modified sol-gel process. The fabrication process of the thin films is discussed in detail. We found that there is a large built-in stress in the thin film, which can be diminished by annealing at 600 ℃, when the gel is turned into solid material through drying and sintering. The Raman scattering spectra of the films with different compositions and structures were investigated. With the help of X-ray diffraction （XRD） analyzer and Raman scattering spectra analyzer, it was found that the thin films with the PT/PZT-PZT/PT structure have reasonable crystallinity and less residual stress. XRD testing shows that the diffraction pattern of the multilayer film results from the superimposition of the PZT and PT patterns. This leads to the conclusion that the PT/PZT-PZT/PT multilayer thin film has a promising future in pyroelectric infrared detectors with high performance.
文摘TGS (triglycine sulfate) is a pyroelectric crystal material which has an excllent pyroelectricity.The LATGS,a kind of doped TGS crystal,in which L α alanine (LA) substitues for glycine partially and induces an internal bias in TGS resulting in permanently poled single domain crystal,becomes the comprehensively used pyroelectric material. Based on the study which was about the locked polarization in LATGS,we select many kinds of aminoacids which have a strong polarity group and a unsymmetry atom to dope into TGS crystals.The aninoacids are LB (L asparagine),LL (L lysine),LH (L histidine) and LG (L glutamid acid).The saturated solutions for above four crystals growth are prepared by TGS doped with different aminoacids in water. Transparent crystals up to several centinetres in size have been grown by circling plate method and the reversible rotation rate of the platform with the crystal was about 90 r/min.There was a prefered growth in the b axis direction,with a growth rate of the b axis of about 1.0-1.2mm/day.The concentrations of aminoacids doped in TGS crystals were determined by a liquid chromatography,the concentrations of different aminoacids are about 10 -3 . It shows that the lattice parameters ( a,b and V )of TGS doped with aminoacids are significant longer than that of pure TGS crystal. We conclude that the pyroelectic cofficient,pyroelectric merit and the locked polarization of four TGS crystals,especially,the internal bield ( E b ) of LLTGS is larger than the LATGS,so that the LLTGS crystal is a promising pyroelectrc material for infrared detector.
基金Support for this study was received from the China National Ph.D.Foundations。
文摘By studying both the microscopic physical and chemical typomorphic characteristics of typical mineral pyrite samples associated with representative gold deposits on the north-central margin of the North China Platform,this paper seeks to identify macroscopic metallogenic mechanisms of gold deposits and to reveal the formation mechanism of lattice gold in pyrite.Typomorphic characteristics of pyrite reveal that pyrite grain size has a negative correlation with gold content.Cubic pyrite,as the dominant crystal form,contains more gold than pentagonal dodecahedral pyrite.Both pyrite crystal forms and chemical compositions indicate that the replacement style of gold deposit formed in a low saturability,low sulfur fugacity,and at temperatures either much higher or much lower than its best forming temperature;comparatively,that of the quartz vein style of gold deposit occurred under conditions with the best temperature,rich in sulfur,and with high sulfur fugacity.The Au/Ag ratios of the pyrites show that both the replacement and quartz vein styles of deposits are mesothermal and hypothermal,while the Co/Ni ratios of the pyrites indicate that the quartz vein style is of magmatic-hydrothermal origin.The X-ray diffraction intensity of pyrite rich in gold is lower than that of pyrite poor in gold at the quartz vein style.In general,with an increase in gold content in pyrite,the total sum intensityΣI decreases.The pyroelectricity coefficient has a negative correlation trend with the values of(Co+Ni+Se+Te)-As and(Co+Ni+Se+Te)/As.The pyrite pyroelectricity of the replacement style is N-type,indicating that it formed under low sulfur fugacity,while that of the quartz vein style is a mixture of P-N types,indicating that it formed under high sulfur fugacity.On the pyroelectricity-temperature diagram,pyrite of the replacement style is mainly distributed between 200 and 270°C,while that of the quartz vein style varies between 90–118 and274–386°C,demonstrating a multistage forming process.In contrast to previous researchers'conclusions,the authors confirm the existence of lattice gold in pyrites through the use of an electron paramagnetic resonance(EPR)test.Au in the form of Au~+,entering pyrite as an isomorph and producing electron–hole centers,makes the centers produce spin resonance absorption and results in EPR absorption peak II.The intensity of auriferous pyrite absorption peak II has certain direct positive correlations with pyrite gold content.The#I and#III absorption peaks of pyrites possibly result from the existence of Ni^(2+)and/or Cu^(2+).γ1,γ2,andγ3 are the strongest and most typical absorption peaks of the infrared spectra of the pyrites.Generally,with the increase in gold content in the pyrite samples,γ1,γ2,andγ3 tend to shift to higher wavenumbers,and the gold content in the pyrite samples has a positive correlation with their relative absorbance.
文摘Located at the boundary of Chongli county, Chicheng county and Xuanhua county of Heibei province, the Dongping gold deposit is genetically affiliated to the late Jurassic- early Cretaceous volcanics and intrusives. The ore body is quartz vein- and alteration-type and pyrite and quartz are the dominant gold-bearing minerals.
文摘National parks are highly valuable natural areas and have the potential to attract a large number of visitors.The number of visitors at national parks is systematically increasing,often exceeding Tourism Carrying Capacity(TCC)of trails.This situation requires adjusting the number of park visitors to adapt to sustainable management systems of visitor flow,thus preventing or counteracting overtourism.The aim of the study is to propose a comprehensive method for tourists monitoring in mid-mountain national park presented on the example of the Sto?owe Mountains National Park(SMNP)in Poland,called as Monitoring System of tourist traffic(MSTT).The study describes six stages procedure of tourists Monitoring System creation and application as an optimal measurement technique.The MSTT enabled a multidimensional analysis of tourist traffic in SMNP.With the help of 39 pyroelectric sensors and surveys data spatio-temporal characteristic of visitor flow was obtained.The data generated in MSTT included hourly,daily,weekly,monthly,and annual reports,taking into account the direction of traffic measuring both directions:entries(IN),exits(OUT)and passages(IN+OUT).The results from pyroelectric sensors were supplemented with field surveys,where visitor’s motivations,preferences,and behaviours were determined.In 2017 a total of 871,344 visitors were recorded in SMNP what causes one of the most popular national parks in Poland.The SMNP is a suitable destination for short breaks leisure visits in wilderness.In order to sustain MSTT methodology in the long-run the set of guidelines together with the workload estimates were presented.In the future,the MSTT can be further developed,including monitoring of climbing,cycling,cross-country skiing,car traffic and illegal tourism assessment.The MSTT can be considered as a useful tool for tourism management in mid-mountain national parks throughout the entire calendar year.
基金the National Key Research and Development Program of China,Grant/Award Number:2021YFB3800800 and 2021YFC2400400National Natural Science Foundation of China,Grant/Award Number:82022016,51973004,81991505 and 52103312+2 种基金the Beijing Municipal Natural Science Foundation,Grant/Award Number:7222226National Program for Multidisciplinary Cooperative Treatment on Major Diseases,Grant/Award Number:PKUSSNMP-202002Peking University School of Stomatology National Clinical Key Discipline Construction Project,Grant/Award Number:PKUSSNKP-T202101。
文摘Understanding the bioelectrical properties of bone tissue is key to developing new treatment strategies for bone diseases and injuries,as well as improving the design and fabrication of scaffold implants for bone tissue engineering.The bioelectrical properties of bone tissue can be attributed to the interaction of its various cell lineages(osteocyte,osteoblast and osteoclast)with the surrounding extracellular matrix,in the presence of various biomechanical stimuli arising from routine physical activities;and is best described as a combination and overlap of dielectric,piezoelectric,pyroelectric and ferroelectric properties,together with streaming potential and electro-osmosis.There is close interdependence and interaction of the various electroactive and electrosensitive components of bone tissue,including cell membrane potential,voltage-gated ion channels,intracellular signaling pathways,and cell surface receptors,together with various matrix components such as collagen,hydroxyapatite,proteoglycans and glycosaminoglycans.It is the remarkably complex web of interactive cross-talk between the organic and non-organic components of bone that define its electrophysiological properties,which in turn exerts a profound influence on its metabolism,homeostasis and regeneration in health and disease.This has spurred increasing interest in application of electroactive scaffolds in bone tissue engineering,to recapitulate the natural electrophysiological microenvironment of healthy bone tissue to facilitate bone defect repair.
文摘MnO_2doped PbTiO_3 ceramics was prepared by means of solgel method, its density and some electric properties were investigated. The results showed that it was feasible to prepare multicomponent PbTiO_3 solgel series with the aid of solgel method, the obtained MnO_2doped PbTiO_3 ceramics showed a highpurity, uniform component, better dense structure, hardly crack, and had good dielectric, piezoelectric, ferroelectric and pyroelectric properties.
基金supported by the National Basic Research Program of China (973 Program) (Grant No. 2009CB623306)the National Natural Science Foundation of China (Grant No. 60528008)+1 种基金the Key Science and Technology Research Project from the Ministry of Education of China (Grant No. 108180)the National Natural Science Foundation of China-NSAF (Grant No. 10976022)
文摘This paper investigates the pyroelectric of poled antiferroelectric （AFE） ceramic Pbo.97Lao.02 （Zro.69Sno.196 Ti0.114）03 and its remnant polarization dependence of hydrostatic pressure. The results show that the bound charges of poled sample can be released in short time by temperature field or pressure field. The released charge abruptly forms a large pulse current. The phenomena of released charge under external fields result in the ferroelectric-AFE phase transition induced by temperature or hydrostatic pressure.
基金supported by the National Natural Science Foundation of China(No.11172117)Doctoral Fund of Ministry of Education of China(No.20120211110005)the Foundation for Innovative Research Groups of the NNSFC(No.11121202)
文摘A finite element approach based on the micromechanics was performed to estimate the multi-field properties of electro-magneto-thermoelastic composites. The thermal field and the involved pyroelectric and pyromagnetic effect of the multi-phase composite materials were taken into account in the investigation and implemented in the finite element modeling. The multi- fields related to the electric field, magnetic field, deformation and temperature field, as well as their coupling effects of the smart composites under periodic boundary conditions were obtained numerically. Especially, by means of the homogenization approximation, the effective thermal ex- pansion coefficients, pyroelectric coefficients, pyromagnetic coefficients and other elastic, electric, and magnetic properties for the piezoelectric material, piezomagnetic material and magnetoelec- tric material were calculated, respectively. Some results are compared to the theoretical predictions by the well-known Mori-Tanaka method to show good agreements.
