Abstract A series of ferroelectric ceramic models with grain and grain‐boundary structures different sizes are established via Voronoi tessellations. phase‐field model is introduced to study the dielectric breakdown strength these ceramics. Afterward, relation between electric displacement field hysteresis loop calculated using a finite element method based on classical modified hyperbolic tangent model. The results indicate that as size decreases, enhanced, but permittivity reduced....

A record-high breakdown strength (790 kV cm⁻¹) and high energy density (5.04 J cm⁻³) are obtained in BTAS/BTBZNT ceramics with a layer-by-layer structure.

Four different p-type doping GaN photocathodes are activated by Cs/O, and the quantum efficiency (QE) curves obtained. According to QE equation, fitted. Both fitting results show that optimal concentration is at 1017 cm−3. The electron diffusion length surface-electron escape probability can be balanced well To a certain degree, thick emission layer conducive improving QE, which more obvious with long wavelength.

Dielectric capacitors with ultrafast charge-discharge rates are extensively used in electrical and electronic systems. To meet the growing demand for energy storage applications, researchers have devoted significant attention to dielectric ceramics excellent properties. As a result, awareness of importance pulsed discharge behavior conducting characterization studies has been raised. However, temperature stability behavior, which is power still not given necessary consideration. Here, we...

To describe the clinical and radiographic outcomes of patients with severe post-tubercular kyphosis (PTK) in adults who underwent modified posterior vertebral column resection (mPVCR). A retrospective analysis was conducted on data from 22 PTK surgical treatment. All received a one-stage mPVCR deformity correction. General information, radiological parameters including angle (KA) sagittal vertical axis (SVA), functional America Spinal Injury Association (ASIA) grades, Oswestry Disability...

GaN samples are activated by Cs/O under illumination of deuterium lamp, 300 nm monochromatic light with power 70 μW and 35 μW, respectively. Photocurrent is detected before activation lamp. Quantum efficiency (QE) tested after activation. The results indicate that have higher QE than no obvious difference between different light. photocurrent inhibits the adsorption Cs on surface, which decrease GaN.

针对负电子亲和势(NEA) GaN光电阴极成功激活后的量子效率问题,利用自行研制的紫外光谱响应测试仪器,测试了成功激活的NEA GaN光电阴极的光谱响应,给出了230—400 nm波段内反射模式NEA GaN光电阴极的量子效率曲线.测试结果表明:反射模式下NEA GaN光电阴极在230nm具有高达37.4%的量子效率,在GaN光电阴极阈值365 nm处仍有3.75%的量子效率,230 nm和400 nm之间的抑制比率超过2个数量级.文中还结合国外的研究结果,综合分析了影响量子效率的因素.

A depth grade doping sample gallium nitride (GaN) photocathode was designed to obtain an extremely high quantum efficiency (QE). Two other uniform samples were prepared in the same procedure as contrast. The calibrated QE curves achieved; by comparing theoretical calculated values with experimental plots, escape probability and diffusion length fitted. value of gradient is 68.7% at 5.17 eV; fitted be 250 nm which much higher than samples. That explains why depth-grade-doping can improve GaN...

In recent years, more and attention has been attracted by fine denier polyester fibers in electronic information industry due to their unique structural excellent mechanical properties. As known, the properties of have a close relationship with melt-spinning process parameters, thus, it is worth further exploring influence parameters on fiber (namely breaking strength, elongation at break CV strength). This study aims develop novel prediction model based artificial neural network (ANN)...

A 150-nm-thick GaN photocathode with a Mg doping concentration of 1.6 × 1017 cm−3 is activated by Cs/O in an ultrahigh vacuum chamber, and quantum efficiency (QE) curve the negative electron affinity transmission-mode (t-mode) obtained. The maximum QE reaches 13.0% at 290 nm. According to t-mode equation solved from diffusion equation, fitted. From fitting results, escape probability 0.32, back-interface recombination velocity 5 104 cm·s−1, length 116 Based on these parameters, influence...

GaN samples 1–3 are cleaned by a 2:2:1 solution of sulfuric acid (98%) to hydrogen peroxide (30%) de-ionized water; hydrochloric (37%); or 4:1 (30%). The activated Cs/O after the same annealing process. X-ray photoelectron spectroscopy different ways wet chemical cleaning shows: sample 1 has largest proportion Ga, N, and O among three samples, while its C content is lowest. After activation quantum efficiency curves show best photocathode performance. We think method process which will...

Transmission-mode GaN photocathodes with the emission layer thickness of 150 nm and doping concentration 1.6×1017 cm-3 were grown by metal-organic chemical vapor deposition (MOCVD) activated in ultra-high vacuum system. The result was tested Multi-information test shape transmission-mode NEA photocathode quantum yield curves looks like Chinese charocter 门 for "door", had flat high response between 255 355 nm, highest 13% appeared at 290 nm. When wavelength less than decreased because...

GaN is becoming a promising material in ultraviolet detection and vacuum electronic source field for its good performance. High quantum efficiencies of greater than 70% 30% have been achieved the opaque mode transparent photocathode, respectively. This paper reviews progress photocahtode three important fields,including structure design, surface cleaning Cs/O activation, analyzes key factors influencing efficiency, evaluates prospect development.

Negative electron affinity GaN photocathode with greatly advanced photoelectricity performance is described. The research of focuses on the three points, i. e. , quantum yield, energy distribution and surface model, in last decade. domestic still its infancy, basic theory not established, preparation technology mature. In this paper we review emission mechanism, material growth, cleaning, activation process optimization, varied-doping structure design stability photocathode. latest...

Negative electron affinity (NEA) Gallium Nitride (GaN) photocathode is an ideal new kind of UV photocathode. NEA GaN widely used in such fields as high-performance ultraviolet photoelectric detector, beam lithography etc. The preparation negative gallium nitride relates to the growth technology, cleaning method, activation method and evaluation mainstream technology metal organic chemistry vapor phase deposits molecule epitaxial halide were discussed. chemical heat for given detail. After...