Pyroelectricity effect on photoactivating palladium nanoparticles in PbTiO3 for Suzuki coupling reaction

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.

Phenomenological Theory of Pyroelectricity

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.

Pyroelectric Plate with Magnetoelectric Effect

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.

THE VARIATIONAL PRINCIPLES FOR PYROELECTRIC MEDIA

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.

Pyroelectric Bi_5-x(Bi₂S₃)₃₉I₁₂S: Fibonacci Superstructure, Synthesis Options and Solar Cell Potential

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.

Research on Raman-scattering and Fabrication of Multilayer Thin Film with Different Structures and Components Based on Pt/Ti/Si3N4/SiO2/Si Substrate

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.

氨基酸系列改性TGS晶体研究

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.

Correlations between trace elements in pyrite and gold mineralization of gold deposits on 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.

Correlation between intrinsic dipole moment and pyroelectric coefficient of Fe-Mg tourmaline

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.

Genetic Mineralogy of the Pyrite and Quartz in Dongping Gold Deposit, Hebei Province: Implications for Gold Prospecting

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.

Monitoring System of tourist traffic(MSTT) for tourists monitoring in mid-mountain national park,SW Poland

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.

The bioelectrical properties of bone tissue

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.

The Sol-gel Preparation and Electric Properties of MnO_2-doped PbTiO_3 Ceramics

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.

Release of charges under external fields of PbLa(Zr,Sn,Ti)O_3 ceramic

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.

Gradient refractive structured NiCr thin film absorber for pyroelectric infrared detectors

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.

Electrocaloric effect and pyroelectric properties of organic–inorganic hybrid （C2H5NH3）2CuCl4

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.

Dielectric and Pyroelectric Characteristics of the Infrared Sensitive (Pb_(1-x)Sr_x)TiO_3 Ceramics

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.

Preparation of Lead-based Perovskite Structure Ferroelectric Thin Films by Sol-Gel Method and the Properties of the Films

Polycrystalline PZT,PLT and PbTiO ferroelectric thin films,highly oriented PbTiOferroelectric thin films and epitaxial growth PZT,PLT ferroelectric thin films with per-ovskite-type structure were prepared by the sol-gel method.Ferroelectric properties of theceramic thin films were confirmed by P-E hysteresis loops.The pyroelectric and opticalproperties were also measured.

Effective Pyroelectric Coefficient and Polarization Offset of Compositionally Step-like Graded Ferroelectric Structures

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.

Minimum sensing cell measurement in network domain based on PIR sensor array

To reasearch on the infrared target perception by pyroelectric infrared (PIR) sensor in network domain measurement,a closed sensing network domain composed of eight-PIR-sensor array is proposed for the minimum sensing cell measurement in network domain and to realize the moving target perception and trajectory prediction. Moreover,the feasibility and accuracy of the proposed method are verified through experiments. The experimental results demonstrate that the maximum error between the real trajectory and the predicted trajectory of the minimum sensing cell measurement method is 0.64 m,which can achieve infrared target perception and moving trajectory prediction.