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551.
《Ceramics International》2019,45(13):16275-16278
We have reported the successful growth of Mg2GeO4 nano-crystals by simple thermal evaporation technique. The Mg and Ge metal powders were evaporated on the Si substrate and kept the oxygen flow rate of 100 sccm. The modulation of structural, morphological, thermoelectric and electrical properties was performed by controlling the thermal energy of carriers using different annealing temperatures. XRD data showed a peak at 61.80 which was related to (212) plane of Mg2GeO4. XRD data further suggested that sample annealed at 700 °C has stable crystal structure while sample annealed at 800 °C posses degraded structure because the presence of highest density of donors defects. This defect concentration causes an increase in the conductivity of annealed samples as evident by the Hall data. This argument was also supported by Raman spectroscopy which showed that sample annealed at 700 °C has strongest Mg2GeO4 Raman peak. SEM images also verified the smooth surface of the sample annealed at 700 °C. The temperature dependent (25–100 °C) Seebeck effect measurements were performed to calculate the Seebeck coefficient of Mg2GeO4 nano-crystals at different measurement temperatures. The highest value of room temperature Seebeck coefficient (397 μV/0C) for the sample annealed at 800 °C is due the high density of carrier concentration. 相似文献
552.
553.
Methane‐air partial oxidation to methanol over a ceramic‐supported Fe2O3‐CuO catalyst was investigated in a post‐plasma catalytic reactor at ambient conditions. The multicomponent catalyst exerted a better catalytic performance than the monocomponent Fe2O3 catalyst. Characterization of the catalysts by XPS showed that incorporation of the CuO additive to a Fe2O3‐based catalyst resulted in an increase of lattice oxygen in the surface of the catalyst which facilitated selective methane oxidation. Hydrogen temperature‐programmed reduction revealed that addition of the CuO promoter could improve the reduction performance of the catalyst. Moreover, this catalyst showed excellent stability and resistance against carbon deposition in the extended reactions while maintaining catalytic activity. A post‐plasma catalytic mechanism is proposed with three main pathways to methanol synthesis. 相似文献
554.
D. N. Njie 《Drying Technology》2013,31(6):1161-1171
Abstract Desorption isotherms of water in trifoliate yam (Dioscorea dumetorum Pax) were determined using a dynamic gravimetric method at temperatures of 20°, 34°, 46° and 62°C, in the relative humidity range from 11 to 86% A nonlinear least squares regression program was used to fit the measured data to the Modified Henderson, the Modified Halsey, the Chung-Pfost, and the GAB sorption models. The GAB model gave the best fit. The net isosteric heat of sorption, estimated using the Clasius-Clapeyron equation, ranged from 1412 kJ/kg at a moisture content of 0.05 kg/kg, dry basis, to 325 kJ/kg at 0.20 kg/kg. Results obtained in this study should be important in controlling the water content of yam during processing, handling, packaging and storage. 相似文献
555.
作者认为 ,香港的后殖民建筑文化不是要寻回正宗的民族主义文化 ,也不是要继承殖民主义的变化 ,而是试图解构原本对立的、相互排斥的殖民主义和民族主义的文化 ,然后在两个主体文化空间的边缘上 ,自取所需地建立本土主义的“灰色空间”。文章探讨了香港建筑中后殖民文化的倾向和问题。 相似文献
556.
557.
针对大范围、复杂的野外测量环境下,多点布设外业测控点,难度较大,且耗时耗力的问题,文章以后差分方法优化POS数据精度为研究基点,基于后差分原理,进行两层面创新。首先,基于外方位元素对POS数据精度的影响,利用相机延迟测定及控制技术获取真实的POS数据,并融合码伪距和载波相位双差方程,通过建构基于UbloxN-M8T芯片的后差分GNSS模块,来消除POS数据误差;同时,使用联立GPS与IMU观测值方程的光束法区域网平差模型,通过平差循环迭代运算,获取精度最优的POS数据,并据此,在不同的控制点方案下生成DOM正射影像,通过成像精度测评,得出后差分可显著提升POS数据精度,且在极少控制点、无架构航线下的效用更为明显。 相似文献
558.
559.
When data security is facing growing threats, ordinary encryption techniques cannot meet the needs of comparing, sharing, and classifying data hidden in ciphertexts. At the same time, the advent of the quantum computing era has brought unprecedented challenges to traditional cryptography. Fortunately, a lattice-based PKEET scheme can solve the above problems. In this paper, we design a lattice-based PKE-DET scheme that can support the delegated tester function with satisfying anti-quantum computing security and resisting OMRA attacks. To the best of our knowledge, this is the first PKE-DET scheme that has both kinds of security at the same time. Under the standard model, we prove the security of the scheme based on the LWE hardness assumption. Compared with existing schemes, our scheme has many advantages, such as high security, delegated tester authorization, and small storage space. 相似文献
560.
《Ceramics International》2023,49(6):8718-8724
Recently, LiTa2PO8 (LTPO) has attracted interest as a potential Li-ion solid electrolyte material because of its high bulk ionic conductivity and low grain boundary ionic conductivity. However, most ceramic-based solid electrolytes are fabricated via the high-temperature sintering process (typically above 1000 °C); such temperatures can cause the evaporation of Li from the compound. To replace high-temperature sintering of ceramics, the cold sintering process (CSP) was introduced; this process enables the densification of ceramics and composites at extremely low temperatures (below 300 °C). In this work, we investigate the effect of using the CSP and post annealing on the microstructure and Li-ion conductivity of LTPO pellets. It is found that the CSP pellets have an amorphous phase between particles. This intermediate amorphous phase creates a better contact between particles and is hypothesized to lead to more Li-ion migration paths. The CSP pellet is found to have a high density and high ionic conductivity of (1.19 × 10?5 S/cm). The pellet obtained via the CSP has Li-ion conductivity similar to that of the pellet obtained via dry pressing after it has been annealed. The CSP pellet after post annealing shows good connections between particles and a high Li-ion conductivity of 1.05 × 10?4 S/cm, which is comparable to the conductivity of a pellet obtained via high-temperature sintering. This work provides new evidence that the CSP is a promising alternative to high-temperature sintering for fabricating ceramic solid electrolytes. 相似文献