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Electric field-induced toughening in GaN piezoelectric semiconductor ceramics
摘要： In this paper, the effect of an applied electric field on fracture toughness of polarized GaN piezoelectric semiconductor ceramics was studied by using experimental and numerical methods. The results show that fracture toughness increases by 22% under a field intensity of 0.83 kV cm?1, and with further increase of the electrical filed, fracture toughness remains unchanged. This is completely different from the fracture characteristics of traditional piezoelectric ceramics that is thought to decrease with an applied electric field. The reason for such a difference is attributed to the redistribution of free electrons. It is expected that this finding will be instructive to the reliability design of piezoelectric semiconductor structures and devices.
关键词： GaN,Electric field,Fracture toughness,Piezoelectric semiconductor ceramics,Toughening
更新于2025-09-23 15:23:52
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Tip effect of a micro-needle in a diamond-coating external field
摘要： This study investigated the mechanism of the tip effect in an external field: that is the influence of an electric field on the tip shape, and a temperature field on the film uniformity, of a micro-needle during diamond coating. A bias field during magnetron sputtering was used to investigate the electric effect on the tip and hot-filament chemical vapor deposition (HFCVD) was used to investigate the thermal effect on the tip. The results showed that, (1) in the bias field during magnetron sputtering, the tip shape was affected by the accumulation of electric charge exerting an electric force on the tip; (2) in the temperature field of HFCVD, the film uniformity on the tip degenerated as a result of the high diffusion and evaporation of activated free radicals arising from the thermal effect; this hindered the nucleation and growth of the diamond film; (3) under the action of the external field, the internal free electrons of the micro-needle moved to preferentially occupy the tip, which has a large curvature, leading to a tip effect.
关键词： Uniformity,Electric field,Deformation,Temperature,Tip effect
更新于2025-09-23 15:23:52
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Enhanced Photocatalytic Activity by the Combined Influence of Ferroelectric Domain and Au Nanoparticles for BaTiO <sub/>3</sub> Fibers
摘要： Ferroelectric particles have been applied in the photocatalytic field because the spontaneous polarization results in the internal electric field, which can accelerate the separation and migration of photogenerated carriers. In this study, the BaTiO3 (BT) fibers are synthesized by electrospinning. The BT fibers calcined above 800 °C exhibit a strong ferroelectric property, which is verified by a typical butterfly-shaped displacement-voltage loop. It is found that the BT fibers with the single-domain structure exhibit better photocatalytic performance than that with the multi-domain configuration. When the single-domain transforms into multi-domain, the integrated internal electric field correspondingly breaks up, inducing that the internal electric field might cancel each other out and diminish the separation of photogenerated carriers. Also, the Au nanoparticles can improve the photocatalytic activity further on account of the surface plasmon resonance. Therefore, it is suggested that Au nanoparticles decorated on ferroelectric BT nanomaterials are promising photocatalysts.
关键词： photocatalytic performance,Ferroelectric property,domain configuration,internal electric field
更新于2025-09-23 15:23:52
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Electric field assisted ion adsorption with nanoporous SWCNT electrodes
摘要： The permeable single wall carbon nanotube (SWCNT) film electrodes of high electrical conductivity for filtration of ions are promising for future water treatment technology. The permeable SWCNT film electrodes were obtained by the use of the Zn/Al-based dispersant-aided SWCNT ink. The G band peak position and ID/IG value of Raman spectra do not change before and after the polarization of the SWCNT electrodes, showing the robustness of permeable SWCNT film electrodes. The analysis of N2 adsorption isotherms showed that microporosity and specific surface area of the SWCNT electrodes were larger than those of the pristine SWCNT, due to the debundling of SWCNTs and removal of the caps of SWCNT on the dispersion treatment. Application of the electric voltage above ?3 V to the SWCNT electrodes enhanced markedly the adsorption-mediated permeability of K+ ions, reaching the removability of 90%. The removability dependence of Na+ ions on the initial ion concentration showed that the SWCNT permeation electrodes filter was efficient for diluted Na+ ionic solution. The ions of smaller Stokes radius were adsorbed for the mixed ionic solution of Li+, Na+, K+, Rb+, and Cs+, suggesting that the inner tube space of SWCNT electrodes is important for adsorption of ions.
关键词： Permeable electrodes,Electrosorption,Electric field assistance,Ion adsorption,Water treatment,Single wall carbon nanotube
更新于2025-09-23 15:23:52
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Study of the relationship between metal-assisted chemical etching and direction of the applied electric field
摘要： Metal-assisted chemical etching (MACE) has been proposed as a promising alternative for the fabrication of micro/nano-structures on silicon with simple process and low cost. Electric field can be applied during the reaction to control the motion of charged particles so as to accelerate the reaction and form uniform vertical trenches with high aspect ratio. In this paper, boron doped p-type (100) silicon wafers with resistivity of 20～30 Ω·cm was used as substrates. After coated with layers of 5 nm Ti and 10 nm Au, the silicon substrate was immersed into the etchant containing hydrofluoric acid (HF) and hydrogen peroxide (H2O2) with high HF-to-H2O2 concentration ratio (ρ) and an applied voltage of 40 volts. It was found that the direction of the applied electric field had a great influence on morphologies of the trenches. Deeper trenches with vertical sidewalls and relatively smoother bottom were observed when silicon substrate was connected to cathode of the power supply. Possible interpretation to these phenomena was proposed, and the effect of the electric field intensity and doping concentration was further studied.
关键词： trench morphology,metal-assisted chemical etching,electric field,HF-to-H2O2 ratio,electrode connection
更新于2025-09-23 15:23:52
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Enhanced photo-catalytic performance by effective electron-hole separation for MoS2 inlaying in g-C3N4 hetero-junction
摘要： The MoS2/g-C3N4 heterojunction composite (marked as MoS2/g-C3N4-H) was successfully prepared via calcining the melamine coated MoS2 nano-sphere, where the thin g-C3N4 nano-sheets were tightly grown on the surface of MoS2 nano-sphere to form MoS2 inlaying in g-C3N4 heterostructure. The detailed charge transfer mechanism was discussed by combining theoretical calculation and experiments, in which the intrinsic cause of photo-generated charge separation and transfer was determined as the directional built-in electric field driven by different Fermi levels of MoS2 and g-C3N4. Comparatively, the enhanced photo-catalytic performance and stability of the sample were assessed by degrading the Rhodamine (RhB) and reducing the Dichromate (Cr6+) solutions under the irradiation of the simulated sunlight, which could be attributed to the widened spectral absorption range and improved electron-hole separation rate. Based on above results, the photo-catalytic mechanism involving redox reactions was also clearly proposed.
关键词： MoS2,Built-in electric field,Photocatalyst,Heterojunction,g-C3N4
更新于2025-09-23 15:23:52
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[IEEE 2018 International Symposium on Electromagnetic Compatibility (EMC EUROPE) - Amsterdam (2018.8.27-2018.8.30)] 2018 International Symposium on Electromagnetic Compatibility (EMC EUROPE) - High-Resolution Near-Field Imaging and Far-Field Antenna Measurements with Atomic Sensors
摘要： Measurements of radio-frequency (RF) electric fields using atomic sensors based on quantum-optical spectroscopy of Rydberg states in vapors has garnered significant interest in recent years for the establishment of atomic standards for RF electric fields and towards the development of novel RF sensing instrumentation. Here we describe recent work employing atomic sensors for sub-wavelength near-field imaging of a Ku-band horn antenna. We demonstrate near-field imaging capability at a spatial resolution of λ/10 and measurements over a 72 to 240 V/m field range using off-resonance AC-Stark shifts of a Rydberg-atom resonance. A fiber-coupled atomic-sensor probe is also employed in far-field measurements of a WR-90 standard gain horn.
关键词： electromagnetic compatibility,Rydberg,atom,quantum sensing,RF,metrology,antenna characterization,microwave,Atomic sensors,electric field,antenna,radio-frequency
更新于2025-09-23 15:23:52
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An Overview of the Ultrawide Bandgap Ga2O3 Semiconductor-Based Schottky Barrier Diode for Power Electronics Application
摘要： Gallium oxide (Ga2O3) is a new semiconductor material which has the advantage of ultrawide bandgap, high breakdown electric field, and large Baliga’s figure of merit (BFOM), so it is a promising candidate for the next-generation high-power devices including Schottky barrier diode (SBD). In this paper, the basic physical properties of Ga2O3 semiconductor have been analyzed. And the recent investigations on the Ga2O3-based SBD have been reviewed. Meanwhile, various methods for improving the performances including breakdown voltage and on-resistance have been summarized and compared. Finally, the prospect of Ga2O3-based SBD for power electronics application has been analyzed.
关键词： Breakdown electric field,Baliga’s figure of merit,On-resistance,Ultrawide bandgap semiconductor,Gallium oxide (Ga2O3),Power device,Schottky barrier diode (SBD)
更新于2025-09-23 15:22:29
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Ultra-low hysteresis electric field-induced strain with high electrostrictive coefficient in lead-free Ba(Zr Ti1-)O3 ferroelectrics
摘要： From the application point of view, high electric field-induced strain with ultra-low hysteresis or hysteresis-free characteristic is highly desired in high-precision displacement actuators. In this work, lead-free Ba(ZrxTi1-x)O3 (BZT) ferroelectrics with x in the range between 0.02 and 0.1 were fabricated by a conventional solid state reaction method. The structural evolution and electrical properties were investigated systematically with an emphasis on electrostrictive effect. As x increases from 0.02 to 0.1, the crystal lattice parameters (a and c axes) increase while the tetragonality (c/a-1) goes down. In addition, the Curie temperature (TC) of BZT decreases gradually, while the temperatures corresponding to tetragonal-to-orthorhombic (T-O) and orthorhombic-to-rhombohedral (O-R) phase transitions increase. Ultra-low hysteresis (<8%) and high electric field-induced strains (>0.15% at 60 kV/cm) are observed in all studied compositions. Most importantly, a high longitudinal electrostrictive coefficient Q33 (0.0453 m4/C2) was also identified in x=0.1 composition. This work not only reports high electric field-induced strains with ultra-low hysteresis and high Q33 in lead-free BZT ferroelectrics, but also indicates a potential application for BZT ceramics in high-precision displacement actuators.
关键词： Electrostriction,Ferroelectric,Lead-free,Electric field induced strain,BZT
更新于2025-09-23 15:22:29
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Electric-field control of spin accumulation direction for spin-orbit torques
摘要： Electric field is an energy-efficient tool that can be leveraged to control spin–orbit torques (SOTs). Although the amount of current-induced spin accumulation in a heavy metal (HM)/ferromagnet (FM) heterostructure can be regulated to a certain degree using an electric field in various materials, the control of its direction has remained elusive so far. Here, we report that both the direction and amount of current-induced spin accumulation at the HM/FM interface can be dynamically controlled using an electric field in an oxide capped SOT device. The applied electric field transports oxygen ions and modulates the HM/FM interfacial chemistry resulting in an interplay between the spin Hall and the interfacial torques which in turn facilitates a non-volatile and reversible control over the direction and magnitude of SOTs. Our electric-field controlled spin-orbitronics device can be programmed to behave either like the SOT systems with a positive spin Hall angle or a negative spin Hall angle.
关键词： spin-orbit torques,heavy metal/ferromagnet heterostructure,spin accumulation,non-volatile control,electric field control
更新于2025-09-23 15:22:29