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Efficient and Higha??Brightness Broad Area Laser Diodes Designed for Higha??Temperature Operation
摘要： Efficient and High-Brightness Broad Area Laser Diodes Designed for High-Temperature Operation. Advantages of semiconductor laser diodes as efficient high-power laser light sources applicable at elevated ambient temperatures. Semiconductor laser diodes, manufactured as single emitters or laser bars, are highly desired light sources for direct material processing as well as optical pumping of fiber and solid-state lasers. Laser diodes feature high optical output power and efficiency, long lifetimes, low maintenance and consequently low cost of ownership. To improve the usability and extend the application spectrum of high-power laser diodes, relaxed cooling requirements – without compromise in laser performance and lifetime – are required. Therefore, great development efforts are made, both in externally and internally funded research projects, to push the maximum permissible operating temperature of such semiconductor laser diodes to higher levels.
关键词： efficiency,semiconductor laser diodes,high-power laser,brightness,high-temperature operation
更新于2025-09-23 15:19:57
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Performance analysis of cubic silicon carbide solar cell as an appropriate candidate for high temperature application
摘要： In this research article, a 3C–SiC-based single-junction solar cell is evaluated using a two-dimensional finite element method. Effects of n + and p + thicknesses and operating temperature on the performance of n + pp + 3C–SiC solar cell are simulated to find its real efficiency. For a cell with a thickness of 5 μm, the efficiencies of 12.52%, 11.2%, 10.3%, and 8.8% are obtained for n + and p + thicknesses of 0.2 μm, 0.3 μm, 0.4 μm, and 0.5 μm, respectively. It is investigated that the conversion efficiency of a Si-based solar cell is very sensitive to temperature variation. It significantly decreases when the temperature increases while 3C–SiC benefits from the best thermal stability. The efficiency gradients of 0.015%/oK and 0.0087%/oK are obtained from numerical and limitation methods for the 3C–SiC-based solar cells, respectively. It is important to mention that this value is 0.0375%/oK for a single-junction silicon solar cell.
关键词： Silicon solar cells,Silicon carbide,High bandgap,High temperature,3C–SiC
更新于2025-09-23 15:19:57
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Structural and thermodynamic properties of cubic sphalerite aluminum nitride under hydrostatic compression
摘要： The present work aims to investigate the structural phase stability and thermodynamic properties of aluminium nitride with cubic zinc-blende structure at normal and high pressures (up to 5 GPa) and high temperatures (up to 2000 K). In this study, we use the pseudopotential plane wave method within the framework of the density functional theory with the local density approximation for the exchange-correlation functional. The phase transition pressure has been determined and found to be in very good agreement with several theoretical data. The pressure and temperature dependences of thermodynamic properties are successfully presented, analyzed and discussed in details. Besides, the plasmon energy and microhardness are examined.
关键词： High-pressure,Ab-initio calculation,High-temperature,Thermodynamic properties,Aluminium nitride
更新于2025-09-23 15:19:57
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Recovery kinetics in high temperature annealed AlN heteroepitaxial films
摘要： Based on the experimental dislocation annihilation rates, vacancy core diffusion-controlled dislocation climb was found as a dominant recovery mechanism in high temperature annealing of AlN heteroepitaxial films. Dislocation annihilation mechanisms via dislocation glide (with or without kinks) and vacancy bulk diffusion were found to be less significant. Cross-slip was also ruled out as a possible mechanism as a majority of dislocations in heteroepitaxial AlN films are threading edge dislocations. While dislocation climb through both vacancy bulk and core diffusion could offer a plausible explanation of the recovery process, the activation energy for the vacancy core diffusion-controlled dislocation climb was relatively low (4.3 ± 0.1 eV), as estimated from an Arrhenius plot. The validity of the vacancy core diffusion mechanism was also supported by a large vacancy mean free path (～240 nm), which was comparable to the sample thickness and thus the average dislocation length. Finally, the experimentally observed dislocation density reduction as a function of the annealing temperature and time was in good agreement with the vacancy core diffusion mechanism.
关键词： dislocation annihilation,high temperature annealing,AlN heteroepitaxial films,recovery kinetics,vacancy core diffusion
更新于2025-09-23 15:19:57
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Self-driven all-inorganic perovskite microplatelet vertical Schottky junction photodetectors with a tunable spectral response
摘要： Wavelength-selective perovskite photodetectors (PDs) have many applications in optoelectronic field, such as machine vision, imaging and full-color display. However, the instability of organo-inorganic hybrid perovskite material severely limits the commercialization of perovskite-based PDs. In this work, a more stable all-inorganic perovskite, CsPbBr(3-x)Clx (x = 0, 1, 2, 3) microplatelets (MPs), were employed to fabricate Schottky PDs with a simple vertical structure of ITO/MP/Au. The optimized CsPbBr3 MP Schottky PDs exhibit rapid response speed (75 μs) and very low dark current (2 pA) at zero bias. Meanwhile, the device shows a high on/off ratio (>106), a large specific detectivity (>1012 Jones) and linear dynamic range (LDR = 137 dB) with excellent thermal and long-term stability. Furthermore, a tunable spectral response covering from the ultraviolet to visible range is also demonstrated. These results provide a simple avenue to realize self-driven and spectral tunable all-inorganic perovskite Schottky PDs with good stability.
关键词： all-inorganic perovskite,high temperature tolerance,tunable spectral response,vertical structure Schottky photodetector,weak-light sensitivity
更新于2025-09-23 15:19:57
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Multi-field dependence responses and their micro-structure analysis in YBa <sub/>2</sub> Cu <sub/>3</sub> O <sub/>7a??x</sub> -based second-generation coated conductors with different protective layers by Nd-laser irradiations
摘要： High-temperature superconductors (HTS) are materials that hold great promise for future particle-accelerator plants. YBa2Cu3O7-x-based (YBCO) second-generation coated conductor coils can produce the intense field needed for ion confinement. Such coils can act as a radiation resistance magnet when exposed to radiation, and therefore, it is essential to better understand irradiation responses and defect creation in YBCO superconductors. The influence of laser or ion irradiation on the electrical characteristics of HTS has been studied previously; however, most results remain ambiguous and inconsistent. Degradation of or incremental changes in the critical current of the HTS tap are currently only observed and explained via irradiation dose. The relation between irradiation defects and macro-multi-field responses has yet to be established for YBCO tapes, for magnet design and operation. In this study, YBCO (2 G HTS) taps with Ag, Cu–Ag, and Cu protective cap layers were selected as targets of Nd-laser irradiation, at varying power. Irradiation defects were formed in YBCO taps, and irradiation dose was monitored as a function of superconducting properties and mechanical behaviors. The critical current and its N-values eventually degrade under intense Nd-laser irradiation, and the mechanical behavior of YBCO tapes shows nonlinear features after irradiation. Scanning electron microscopy and x-ray energy-dispersive spectrometry were applied to investigate the micro-defect changes that occurred in the taps after each Nd-laser irradiation dose. Micro-structural observations showed that the protective layers were critical for radiation resistance in YBCO taps. Furthermore, the macro-stress dependence of the critical current field was measured before and after Nd-laser irradiation to establish the relationship with micro-defect morphology by Nd-laser irradiation.
关键词： micro-structure analysis,YBa2Cu3O7-x,critical current,High-temperature superconductors,Nd-laser irradiation
更新于2025-09-23 15:19:57
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A Quantitative Approach To Assess High Temperature Flow Properties Of A Pa 12 Powder For Laser Sintering
摘要： In order to consider thermal conditions involved in laser sintering (LS), the effect of temperature on the flow properties of a polyamide 12 powder was assessed. Shear tests were carried out at temperatures from ambient up to values close to the melting temperature of the polymer. The measurement method provides quantitative descriptors of powder flowability. Experiments indicate that flowability significantly deteriorates when temperature rises and approaches a value of about 20°C lower than the melting temperature. The spreading process may be hindered by natural agglomeration of the material. A simple analysis based on the extrapolation of the bulk flow properties at zero consolidation shows that agglomeration is excluded in the temperature range between 100 and 140°C. This turns out to be the range in which it is known that the material can be used safely for LS applications.
关键词： powder bed fusion,powder flow,flow function,high temperature,agglomeration
更新于2025-09-23 15:19:57
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Ultraviolet absorption cross-section measurements of shock-heated O2 from 2,000a??8,400 K using a tunable laser
摘要： Accurate spectroscopic modeling is critical when measuring time-resolved, state-specific chemical kinetics of diatomic molecules. Here, a spectroscopic model (Stanford model) was developed to accurately simulate oxygen absorption cross-sections in the Schumann-Runge system for non-equilibrium conditions. Cross-sections of shock-heated oxygen (O2) have been measured using a picosecond pulsed ultraviolet (UV) laser, and the viability of two spectroscopic models has been demonstrated. Measurements were taken behind reflected shocks in 2% and 5% O2 in argon (Ar) mixtures around 211.2 nm and 236.9 nm up to initial post-reflected shock temperatures of 10,700 K. Cross-sections were plotted against vibrational temperature and compared to calculated cross-sections from the Stanford model and the Adjusted Spectrum model. Vibrational temperatures for cross-section measurements were calculated for plateaus and peaks in experimental absorbances using a Bethe-Teller relaxation model up to 6,000 K and a steady-state approach above 6,000 K. Vibrational temperatures calculated using the steady-state approach were 3–5% higher than coupled vibration-dissociation (CVD) calculations. The experimental cross-sections agree to within 15% of the Stanford model for both wavelength regimes.
关键词： Spectroscopy,Oxygen,High-temperature,Chemical kinetics,Ultraviolet absorption,Shock tube,Cross-sections,Lasers
更新于2025-09-23 15:19:57
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Development of Picosecond Laser Writing for Heat Resistant FBG Sensors and Adhesion Technique for High Temperature Industrial Plants; ?????3?§??????????????·￥?????????è????±FBG ?????3??μè￡??????¨é???????￡?￥-??¨????????3???????????￥???;
摘要： Pulse laser processing point by point method is applied for heat resistant Fiber Bragg Grating structure. In order to fabricate fine FBG, a close packaged picosecond laser system is used with a CCD camera microscopy. An optical fiber is mounted on a precision translation stage. The stage speed is controlled by the current position and the corrector output. In order to contact the FBG on a metal surface, nano-size colloidal silver adhesive is used under temperature monitoring. Heat expansion of SUS plate can be successfully monitored by strain gauge of the heat resistant FBG. It can be available for monitoring the structural integrity of high temperature industrial plant. Complex coolant piping systems of liquid sodium and molten salt are facing the risk of coolant leakage, which is the most promising usage.
关键词： Structural Health Integrity,Picosecond Laser Processing,Adhesion,High Temperature,FBG
更新于2025-09-23 15:19:57
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A Schottky-junction-based platinum nanoclusters@silicon carbide nanosheet as long-term stable hydrogen sensors
摘要： Hydrogen gas sensors which could be applied in harsh environments (high temperature, corrosion atmosphere, etc.) are highly demanded in special fields such as aerospace and chemical industry. Here, we have successfully produced a platinum nanoclusters@silicon carbide nanosheets (Pt NCs@SiC NSs) gas sensor via a simple one-step wet chemical reduction reaction. The Pt NCs@SiC NSs show good response (15.7%) towards 500 ppm hydrogen under 300 °C. Besides, this device possesses a good linear response towards different hydrogen concentration under 500 ppm and keeps a good stability in one month. The gas sensing properties of Pt NCs@SiC NSs are mainly from the Schottky junction-based structure, in which both reception and transduction process play important roles. This work provides a simple way to prepare high-temperature hydrogen sensors without complex equipment, and the large-scale preparation is also available.
关键词： hydrogen sensing,Pt nanoclusters@SiC nanosheets,chemical reduction reaction,high-temperature
更新于2025-09-23 15:19:57