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
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
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
The CdS/Bi_(2)S_(3) supported three-dimensional(3D)porous faveolate carbon structure(CdS/Bi_(2)S_(3)@C)composite photocatalyst was constructed.Bi_(2)S_(3) nanoparticles are regarded as photothermal agents and pyroelec...The CdS/Bi_(2)S_(3) supported three-dimensional(3D)porous faveolate carbon structure(CdS/Bi_(2)S_(3)@C)composite photocatalyst was constructed.Bi_(2)S_(3) nanoparticles are regarded as photothermal agents and pyroelectric materials to absorb near infrared light(NIR)and convert it into heat.3D porous faveolate of carbon acts as incubator to reduce heat loss and optimize photothermal effects.There is a greater fluctuating temperature difference(ΔΤ)between photothermal effect of Bi_(2)S_(3) and cold photocatalytic system.This enhances the pyroelectric effect that Bi_(2)S_(3) undergoes spontaneous polarization and releases the surface charge.Therefore,the separation of electrons and holes in the CdS photocatalyst can be induced.The COMSOL simulation results show that,the higher pyroelectric potential producted by largerΔΤis more favorable to the photocatalytic process.The hydrogen evolution rate of CdS/Bi_(2)S_(3)@C photocatalyst can reach 5.88 mmol·g^(-1)·h^(-1) with excellent cycle stability.展开更多
A gradient refractive structured NiCr film that has a high extinction coefficient at far infrared range(8-μm–24 μm) is presented as an absorber for pyroelectric infrared detectors. The absorber features high absorp...A gradient refractive structured NiCr film that has a high extinction coefficient at far infrared range(8-μm–24 μm) is presented as an absorber for pyroelectric infrared detectors. The absorber features high absorption efficiency due to the low reflection off the structured surface and high absorption across the film thickness. The refractive index and extinction coefficient are extracted using spectroscopic ellipsometry. It is found that the single NiCr film exhibits an increasing refractive index as the gas atmosphere pressure increases, hence the three-layer gradient NiCr absorber can be fabricated by adjusting the gas atmosphere pressure during sputtering deposition. Essential Macleod software has been used to generate an efficient film structure design and the calculations show similar absorptance trend compared to the experimental measurement result. The results indicate that the gradient refractive structured metal thin film absorber can provide high absorption for applications in thermal sensing.展开更多
The organic–inorganic hybrid(C2H5NH3)2 CuCl4(EA2CuCl4) single crystals are prepared by the solvothermal condition method. The x-ray diffraction, scanning electron microscopy, dielectric permittivity, pyroelectric cur...The organic–inorganic hybrid(C2H5NH3)2 CuCl4(EA2CuCl4) single crystals are prepared by the solvothermal condition method. The x-ray diffraction, scanning electron microscopy, dielectric permittivity, pyroelectric current, and heat capacity are used to systematically investigate the electrocaloric performances of EA2CuCl4. The pyroelectric currents are measured under various voltages, and the electrocaloric effect(ECE) is calculated. Its ECE exhibits an isothermal entropy change of 0.0028 J/kg·K under an electric field of 30 kV/cm associated with a relatively broad temperature span. Further, the maximum pyroelectric coefficient(p) is 4× 10^-3 C/m^2·K and the coefficient β for generating ECE from electric displacement D is 1.068× 10^8 J·cm·K^-1·C^-2 at 240 K. Our results indicate that the ECE behavior of organic–inorganic hybrid EA2CuCl4 is in accordance with Jona and Shirane’s opinion in which the ECE should occur both below and above the Curie temperature Tc.展开更多
Based on the Landau-Dovenshire theory,the thermodynamic potential of(111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr_(1-x)Ti_x)O_3 thin films.Due to the presence of nonlinear cou...Based on the Landau-Dovenshire theory,the thermodynamic potential of(111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr_(1-x)Ti_x)O_3 thin films.Due to the presence of nonlinear coupling terms resulted from the(111) epitaxy with substrates,the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of(001) and(110) oriented films.Pb(Zr_(1-x)Ti_x)O_3 thin films with the Ti composition around the morphotropic phase boundary(MPB) have the giant dielectric and pyroelectric properties.Moreover,Pb(Zr_(1-x)Ti_x)O_3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates.Therefore,the physical properties of(111)oriented Pb(Zr_(1-x)Ti_x)O_3 thin films can be adjusted by choosing the suitable substrates.展开更多
In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It i...In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It is exhibited that the dielectric gradient has a nontrivial influence on the effective pyroelectric coefficient, but has a little influence on the polarization offset; and the polarization gradient plays an important role in the abnormal hysteresis loop phenomenon of the co.mpositionally step-like graded ferroelectric structures. Moreover, the origin of the polarization offset is explored,which can be attributed to the polarization gradient in the compositionally step-like graded structure.展开更多
PST ferroelectric ceramics were fabricated successfully by a two-step method, i e first, PbTiO3 and SrTiO3 were sintered respectively, then mixed and sintered together. The process and characteristics of PST ferroelec...PST ferroelectric ceramics were fabricated successfully by a two-step method, i e first, PbTiO3 and SrTiO3 were sintered respectively, then mixed and sintered together. The process and characteristics of PST ferroelectric ceramics were introduced and researched. Their dielectric and pyroelectric characteristics are as follows dielectric constant 10^4 order, low dielectric loss （lower than 3.0% in the working frequency range of 1-1 000 kHz）, saturation polarization intensity 10^-1 C/m^2 order, and pyroelectric coefficient 10^-3 C/m^2·K order.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
Pyroelectric multi-walled carbon nanotubes:polyvinylidene fluoride (PVDF:MWCT) composite films have been fabriccated by the solution casting technique. The pyroelectric and dielectric properties of the composite films...Pyroelectric multi-walled carbon nanotubes:polyvinylidene fluoride (PVDF:MWCT) composite films have been fabriccated by the solution casting technique. The pyroelectric and dielectric properties of the composite films were examined for their use in uncooled infrared detectors. The properties measured include: 1) dielectric constants and 2) pyroelec- tric coefficient as a function of temperature. From the foregoing parameters, materials Figures-of-merit, for infrared detection and thermal-vidicons, were calculated. The results indicated Figures-of-merit of composite film were higher than pristine polyvinylidene fluoride films.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
Nonlinear photonic crystals[NPCs]with modulated second-order nonlinear coefficients[χ^([2])]enable quasi-phase-matching[QPM]for efficient frequency conversion.Traditional electric-field poling is limited to two-dimen...Nonlinear photonic crystals[NPCs]with modulated second-order nonlinear coefficients[χ^([2])]enable quasi-phase-matching[QPM]for efficient frequency conversion.Traditional electric-field poling is limited to two-dimensional domain engineering and cannot achieve three-dimensional[3D]χ^([2])distributions,while femtosecond laser writing[FLW]offers greater control but introduces crystal damage.In this work,we use the pyroelectric-based fabrication process by performing the cooling step in a vacuum after FLW,suppressing thermal fluctuations,and maximizing the pyroelectric field.Vacuum cooling significantly improves domain inversion probability and uniformity compared to air cooling,making the periodicity close to electrical poling.Real-time polarized microscopy reveals improved domain growth,while nonlinear diffraction analysis confirms negligible refractive index changes.We demonstrate domain-inverted NPCs with a periodicity of 4μm,achieving QPM at near-infrared wavelengths.This method provides a scalable and efficient pathway for advanced nonlinear photonic devices.展开更多
Tactile sensors are a potential solution for material identification.However,current potential tactile sensors for material identification are pressed,expensive,and applications-confined.Here we report a clamped-on py...Tactile sensors are a potential solution for material identification.However,current potential tactile sensors for material identification are pressed,expensive,and applications-confined.Here we report a clamped-on pyroelectric tactile sensor on the basis of a ferroelectric Bi_(0.5)Na_(0.5)TiO_(3) material to identify different film materials.The fabricated device exhibits different heat absorption capacities while in contact with different materials,leading to a different temperature change in the ferroelectric material under the same illumination.As a result,the device can recognize different materials by comparing the pyroelectric charge via integrating the obtained current under the same irradiation of 365nmlight-emitting diode.The clamped-on pyroelectric tactile sensor can identify six individual materials with a high accuracy of 98.8%and a fast response of 40 ms.All of the above processes can be accomplished with an intelligent material identification system.The device provides a new solution for material identification and lays a foundation for smart factories and laboratories.展开更多
Pyroelectric sensors based on pyroelectric effect have a wide range of applications.However,the use of lead-containing materials limits their development.In this paper,Na_(0.5)Bi_(0.5)TiO_(3)-Na_(0.5)Bi_(4.5)TiO_(15)-...Pyroelectric sensors based on pyroelectric effect have a wide range of applications.However,the use of lead-containing materials limits their development.In this paper,Na_(0.5)Bi_(0.5)TiO_(3)-Na_(0.5)Bi_(4.5)TiO_(15)-Mn lead-free pyroelectric ceramics are used as sensitive materials to prepare pyroelectric sensors.Na_(0.5)Bi_(0.5)TiO_(3)-Na_(0.5)Bi_(4.5)TiO_(15)-Mn ceramics can achieve 7.58×10^(-4)C·m^(-2)·K^(-1)high-roomtemperature pyroelectric coefficient and depolarization temperature of 151℃.Due to the low dielectric constant and loss caused by Mn doping,the high detection rate value of 24.382μPa^(-1/2)is obtained.The voltage response rate and specific detection rate of the sensor prepared on this basis can attain the JC-T 2397-2017(ε_(r)>200,tanδ<5%,T_(c)>200,p>3.50×10^(-4)C·m^(-2)·K^(-1))application standard of pyroelectric infrared detectors.Thermoelectric cooler is proposed to adjust the temperature of the sensor,and its voltage response to human radiation is measured.Harnessing the superior pyroelectric attributes of advanced materials and connectable devices,the nascentthermoelectric-pyroelectric detection method is poised to be a subject of intensive investigation and development.展开更多
During the past few decades, pyroelectric sensors have attracted extensiveattention due to their prominent features. However, their effectiveness is hinderedby low electric output. In this study, the laser processed l...During the past few decades, pyroelectric sensors have attracted extensiveattention due to their prominent features. However, their effectiveness is hinderedby low electric output. In this study, the laser processed lithium niobate(LPLN) wafers are fabricated to improve the temperature–voltage response.These processed wafers are utilized to construct pyroelectric sensors as well ashuman–machine interfaces. The laser induces escape of oxygen and the formationof oxygen vacancies, which enhance the charge transport capability on thesurface of lithium niobate (LN). Therefore, the electrodes gather an increasedquantity of charges, increasing the pyroelectric voltage on the LPLN wafers toa 1.3 times higher voltage than that of LN wafers. For the human–machineinterfaces, tactile information in various modes can be recognized by a sensorarray and the temperature warning system operates well. Therefore, the lasermodification approach is promising to enhance the performance of pyroelectricdevices for applications in human–machine interfaces.展开更多
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.
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.
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The CdS/Bi_(2)S_(3) supported three-dimensional(3D)porous faveolate carbon structure(CdS/Bi_(2)S_(3)@C)composite photocatalyst was constructed.Bi_(2)S_(3) nanoparticles are regarded as photothermal agents and pyroelectric materials to absorb near infrared light(NIR)and convert it into heat.3D porous faveolate of carbon acts as incubator to reduce heat loss and optimize photothermal effects.There is a greater fluctuating temperature difference(ΔΤ)between photothermal effect of Bi_(2)S_(3) and cold photocatalytic system.This enhances the pyroelectric effect that Bi_(2)S_(3) undergoes spontaneous polarization and releases the surface charge.Therefore,the separation of electrons and holes in the CdS photocatalyst can be induced.The COMSOL simulation results show that,the higher pyroelectric potential producted by largerΔΤis more favorable to the photocatalytic process.The hydrogen evolution rate of CdS/Bi_(2)S_(3)@C photocatalyst can reach 5.88 mmol·g^(-1)·h^(-1) with excellent cycle stability.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61875031 and 61421002)
文摘A gradient refractive structured NiCr film that has a high extinction coefficient at far infrared range(8-μm–24 μm) is presented as an absorber for pyroelectric infrared detectors. The absorber features high absorption efficiency due to the low reflection off the structured surface and high absorption across the film thickness. The refractive index and extinction coefficient are extracted using spectroscopic ellipsometry. It is found that the single NiCr film exhibits an increasing refractive index as the gas atmosphere pressure increases, hence the three-layer gradient NiCr absorber can be fabricated by adjusting the gas atmosphere pressure during sputtering deposition. Essential Macleod software has been used to generate an efficient film structure design and the calculations show similar absorptance trend compared to the experimental measurement result. The results indicate that the gradient refractive structured metal thin film absorber can provide high absorption for applications in thermal sensing.
基金Project supported by the Fujian Institute of Innovation,Chinese Academy of Sciences(Grant No.FJCXY18040303)the Youth Innovation Promotion of the Chinese Academy of Sciences(Grant No.2013004)the National Natural Science Foundation of China(Grant Nos.51676198 and 51771067)
文摘The organic–inorganic hybrid(C2H5NH3)2 CuCl4(EA2CuCl4) single crystals are prepared by the solvothermal condition method. The x-ray diffraction, scanning electron microscopy, dielectric permittivity, pyroelectric current, and heat capacity are used to systematically investigate the electrocaloric performances of EA2CuCl4. The pyroelectric currents are measured under various voltages, and the electrocaloric effect(ECE) is calculated. Its ECE exhibits an isothermal entropy change of 0.0028 J/kg·K under an electric field of 30 kV/cm associated with a relatively broad temperature span. Further, the maximum pyroelectric coefficient(p) is 4× 10^-3 C/m^2·K and the coefficient β for generating ECE from electric displacement D is 1.068× 10^8 J·cm·K^-1·C^-2 at 240 K. Our results indicate that the ECE behavior of organic–inorganic hybrid EA2CuCl4 is in accordance with Jona and Shirane’s opinion in which the ECE should occur both below and above the Curie temperature Tc.
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe research fund of Jiangsu Province Cultivation base for State Key Laboratory of Photovoltaic Science and Technology+1 种基金Major Projects of Natural Science Research in Jiangsu Province under Grant Nos.15KJA43002,16KJD430006sponsored by Qing Lan Project of Education Department of Jiangsu Province
文摘Based on the Landau-Dovenshire theory,the thermodynamic potential of(111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr_(1-x)Ti_x)O_3 thin films.Due to the presence of nonlinear coupling terms resulted from the(111) epitaxy with substrates,the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of(001) and(110) oriented films.Pb(Zr_(1-x)Ti_x)O_3 thin films with the Ti composition around the morphotropic phase boundary(MPB) have the giant dielectric and pyroelectric properties.Moreover,Pb(Zr_(1-x)Ti_x)O_3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates.Therefore,the physical properties of(111)oriented Pb(Zr_(1-x)Ti_x)O_3 thin films can be adjusted by choosing the suitable substrates.
文摘In this paper, the effective pyroelectric coefficient and polarization offset of the compositionally step-like graded multilayer ferroelectric structures have been studied by use of the first-principles approach. It is exhibited that the dielectric gradient has a nontrivial influence on the effective pyroelectric coefficient, but has a little influence on the polarization offset; and the polarization gradient plays an important role in the abnormal hysteresis loop phenomenon of the co.mpositionally step-like graded ferroelectric structures. Moreover, the origin of the polarization offset is explored,which can be attributed to the polarization gradient in the compositionally step-like graded structure.
文摘PST ferroelectric ceramics were fabricated successfully by a two-step method, i e first, PbTiO3 and SrTiO3 were sintered respectively, then mixed and sintered together. The process and characteristics of PST ferroelectric ceramics were introduced and researched. Their dielectric and pyroelectric characteristics are as follows dielectric constant 10^4 order, low dielectric loss （lower than 3.0% in the working frequency range of 1-1 000 kHz）, saturation polarization intensity 10^-1 C/m^2 order, and pyroelectric coefficient 10^-3 C/m^2·K order.
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.
文摘Pyroelectric multi-walled carbon nanotubes:polyvinylidene fluoride (PVDF:MWCT) composite films have been fabriccated by the solution casting technique. The pyroelectric and dielectric properties of the composite films were examined for their use in uncooled infrared detectors. The properties measured include: 1) dielectric constants and 2) pyroelec- tric coefficient as a function of temperature. From the foregoing parameters, materials Figures-of-merit, for infrared detection and thermal-vidicons, were calculated. The results indicated Figures-of-merit of composite film were higher than pristine polyvinylidene fluoride films.
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 Key R&D Program of China(No.2021YFA1400800)the National Natural Science Foundation of China(Nos.12274474 and 12404376)the Natural Science Foundation of Guangdong(Nos.2022B1515020067 and 2023A1515012867)。
文摘Nonlinear photonic crystals[NPCs]with modulated second-order nonlinear coefficients[χ^([2])]enable quasi-phase-matching[QPM]for efficient frequency conversion.Traditional electric-field poling is limited to two-dimensional domain engineering and cannot achieve three-dimensional[3D]χ^([2])distributions,while femtosecond laser writing[FLW]offers greater control but introduces crystal damage.In this work,we use the pyroelectric-based fabrication process by performing the cooling step in a vacuum after FLW,suppressing thermal fluctuations,and maximizing the pyroelectric field.Vacuum cooling significantly improves domain inversion probability and uniformity compared to air cooling,making the periodicity close to electrical poling.Real-time polarized microscopy reveals improved domain growth,while nonlinear diffraction analysis confirms negligible refractive index changes.We demonstrate domain-inverted NPCs with a periodicity of 4μm,achieving QPM at near-infrared wavelengths.This method provides a scalable and efficient pathway for advanced nonlinear photonic devices.
基金supported by the National Natural Science Foundation of China(Grant 52072041)the Beijing Natural Science Foundation(Grant JQ21007)the University of Chinese Academy of Sciences(Grant Y8540XX2D2).
文摘Tactile sensors are a potential solution for material identification.However,current potential tactile sensors for material identification are pressed,expensive,and applications-confined.Here we report a clamped-on pyroelectric tactile sensor on the basis of a ferroelectric Bi_(0.5)Na_(0.5)TiO_(3) material to identify different film materials.The fabricated device exhibits different heat absorption capacities while in contact with different materials,leading to a different temperature change in the ferroelectric material under the same illumination.As a result,the device can recognize different materials by comparing the pyroelectric charge via integrating the obtained current under the same irradiation of 365nmlight-emitting diode.The clamped-on pyroelectric tactile sensor can identify six individual materials with a high accuracy of 98.8%and a fast response of 40 ms.All of the above processes can be accomplished with an intelligent material identification system.The device provides a new solution for material identification and lays a foundation for smart factories and laboratories.
基金financially supported by the National Key Research and Development Program of China(No.2023YFB4603800)
文摘Pyroelectric sensors based on pyroelectric effect have a wide range of applications.However,the use of lead-containing materials limits their development.In this paper,Na_(0.5)Bi_(0.5)TiO_(3)-Na_(0.5)Bi_(4.5)TiO_(15)-Mn lead-free pyroelectric ceramics are used as sensitive materials to prepare pyroelectric sensors.Na_(0.5)Bi_(0.5)TiO_(3)-Na_(0.5)Bi_(4.5)TiO_(15)-Mn ceramics can achieve 7.58×10^(-4)C·m^(-2)·K^(-1)high-roomtemperature pyroelectric coefficient and depolarization temperature of 151℃.Due to the low dielectric constant and loss caused by Mn doping,the high detection rate value of 24.382μPa^(-1/2)is obtained.The voltage response rate and specific detection rate of the sensor prepared on this basis can attain the JC-T 2397-2017(ε_(r)>200,tanδ<5%,T_(c)>200,p>3.50×10^(-4)C·m^(-2)·K^(-1))application standard of pyroelectric infrared detectors.Thermoelectric cooler is proposed to adjust the temperature of the sensor,and its voltage response to human radiation is measured.Harnessing the superior pyroelectric attributes of advanced materials and connectable devices,the nascentthermoelectric-pyroelectric detection method is poised to be a subject of intensive investigation and development.
基金National Key Research and Development Program of China,Grant/Award Number:2023YFB3210400National Natural Science Foundation of China,Grant/Award Number:52102171+2 种基金Major Scientific and Technological Innovation Project of Shandong Province,Grant/Award Numbers:2021CXGC010603,2023CXGC010110Natural Science Foundation of Shandong Province,Grant/Award Numbers:ZR2021ZD20,ZR2020LLZ006,ZR2021JQ15,ZR2023LLZ008Innovative Team Project of Jinan,Grant/Award Number:2021GXRC019。
文摘During the past few decades, pyroelectric sensors have attracted extensiveattention due to their prominent features. However, their effectiveness is hinderedby low electric output. In this study, the laser processed lithium niobate(LPLN) wafers are fabricated to improve the temperature–voltage response.These processed wafers are utilized to construct pyroelectric sensors as well ashuman–machine interfaces. The laser induces escape of oxygen and the formationof oxygen vacancies, which enhance the charge transport capability on thesurface of lithium niobate (LN). Therefore, the electrodes gather an increasedquantity of charges, increasing the pyroelectric voltage on the LPLN wafers toa 1.3 times higher voltage than that of LN wafers. For the human–machineinterfaces, tactile information in various modes can be recognized by a sensorarray and the temperature warning system operates well. Therefore, the lasermodification approach is promising to enhance the performance of pyroelectricdevices for applications in human–machine interfaces.
