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排序方式: 共有346条查询结果,搜索用时 62 毫秒
1.
针对VO2薄膜在微测辐射热计上的应用,采用射频反应溅射法,在室温下制备氧化钒薄膜;研究了氧分压对薄膜沉积速率、电学性质及成分的影响.通过调节氧分压,先获得成分接近VO2的非晶化薄膜,再在400℃空气中氧化退火,便可制得高电阻温度系数,低电阻率的VO2薄膜,电阻温度系数约为-4%/℃,薄膜方块电阻为R□为100—300kΩ;薄膜在室温下沉积,400℃下退火的制备方法与微机电加工(micro electromechanic
关键词:
二氧化钒
电阻温度系数
氧分压
射频反应溅射法 相似文献
2.
An Electro—Optical Modulator Based on GeO2—Doped Silica Ridge Waveguides with Thermal Poling
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A Mach-Zehnder electro-optic modulator is designed and fabricated based on upper-clad GeO2-doped silica ridge waveguides with thermal poling.The electro-optic coefficient obtained is about 0.05pm/V and is polarizationinsensitive.An extinction ratio of over 17dB is achieved.The transmission loss of the modulator for the TE mode is 2-3dB higher than that for the TM mode after the poling. 相似文献
3.
We report on Raman scattering of VO2 films prepared by radio frequency magnetron sputtering under different conditions. Our investigations revealed that the dominated Raman peaks shift towards high frequency for both V-rich and O-rich VO2 films, compared with the stoichiometry VO2 films. The experimental evidence is presented and the cause for nonstoichiometry dependence of Raman spectra of VO2 films is discussed. 相似文献
4.
研究了CeO_2陶瓷室温下低频和射频的介电谱,并给出了介电常数和介质损耗及其与温度的关系。测量结果表明,此种陶瓷存在弛豫极化,其偶极子的弛豫时间约为5×10~(-9)S。在330℃以下,CeO_2陶瓷的介电常数和介质损耗具有良好的温度特性。在室温下,CeO_2陶瓷在500kHz~50MHz频率范围内具有良好的介电特性。 相似文献
5.
Xiucheng Zheng Xiaoli Zhang Shuping Wang Xiangyu Wang Shihua Wu 《天然气化学杂志》2007,16(2):179-185
In this work, we have reported the influence of the addition of base (KOH) on the physicochemical property of ceria synthesized by alcohothermal process, and the alcohothermal mechanism was also put forward. Furthermore, the prepared CeO2 was used as the support to prepare CuO/CeO2 catalysts via the wet impregnation method. The samples were characterized by N2 adsorption-desorption, X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and temperature-programmed reduction by H2 (H2-TPR). The catalytic properties of the CuO/CeO2 catalysts for low-temperature CO oxidation were studied using a microreactor-GC system. The crystal size of CeO2-A was much smaller than that of CeO2-B, and the corresponding copper oxide catalysts exhibited higher catalytic activity than that of the CeO2-B-supported catalysts under the same reaction conditions. The alcohothermal mechanism indicated that KOH plays a key role in determining the physicochemical and catalytic properties of ceria-based materials. 相似文献
6.
7.
以99.995% Ce(NO3)3和强碱性阴离子交换树脂为原料,采用离子交换-双氧水氧化法合成制备出纳米CeO2晶体。并就离子交换反应中的Ce3+浓度、树脂加入速度和离子交换温度及H2O2加入速度等条件对CeO2粒径的影响进行了探讨,得出了离子交换-双氧水氧化法制备纳米CeO2晶体的最佳工艺条件。FTIR、TEM分析表明,离子交换法无需对合成的Ce(OH)3溶胶进行洗涤即可去除NO3-、CO32-等阴离子杂质,并用H2O2将该溶胶氧化,经真空干燥可制得粒径分布均匀,平均晶粒尺寸约3 nm,高纯度的CeO2粉体。 相似文献
8.
用氢氧化锆共沉-比色法测定二羧乙基锗倍半氧化物的二氧化锗的含量,先将锗与氢氧化锆共沉,沉淀用盐酸溶解,再用四氯化碳萃取盐酸溶液中锗,锗用苯芴酮比色法在510nm,处测定。结果表明,锗在10^-6-10^-5mol/L范围同吸收率与浓度呈线性关系,回收率为98%-103%,变异系数小于5%,该法可用于原料及制占二氧化锗的分析。 相似文献
9.
Fossil fuels are expected to be the major source of energy for the next few decades. However, combustion of nonrenewable resources leads to the release of large quantities of CO2, the primary greenhouse gas. Notably, the concentration of CO2 in the atmosphere is increasing annually at an astounding rate. Electrochemical CO2 reduction (ECR) to value-added fuels and chemicals using electricity from intermittent renewable energy sources is a carbon-neutral method to alleviate anthropogenic CO2 emissions. Despite the steady progress in the selective generation of C1 products (CO and formic acid), the production of multi-carbon species still suffers from low selectivity and efficiency. As an ECR product, ethylene (C2H4) has a higher energy density than do C1 species and is an important industrial feedstock in high demand. However, the conversion of CO2 to C2H4 is plagued by low productivity and large overpotential, in addition to the severe competing hydrogen evolution reaction (HER) during the ECR. To address these issues, the design and development of advanced electrocatalysts are critical. Here, we demonstrate fine-tuning of ECR to C2H4 by taking advantage of the prominent interaction of Cu with shape-controlled CeO2 nanocrystals, that is, cubes, rods, and octahedra predominantly covered with (100), (110), and (111) surfaces, respectively. We found that the selectivity and activity of the ECR depended strongly on the exposed crystal facets of CeO2. The overall ECR Faradaic efficiency (FE) over Cu/CeO2(110) (FE ≈ 56.7%) surpassed that of both Cu/CeO2(100) (FE ≈ 51.5%) and Cu/CeO2(111) (FE ≈ 48.4%) in 0.1 mol·L-1 KHCO3 solutions with an H-type cell. This was in stark contrast to the exclusive occurrence of the HER over pure carbon paper, CeO2(100), CeO2(110), and CeO2(111). In particular, the FE toward C2H4 formation and the partial current density increased in the sequence Cu/CeO2(111) < Cu/CeO2(100) < Cu/CeO2(110) within applied bias potentials from -1.00 to -1.15 V (vs. the reversible hydrogen electrode), reaching 39.1% over Cu/CeO2(110) at a mild overpotential (1.13 V). The corresponding values for Cu/CeO2(100) and Cu/CeO2(111) were FEC2H4 ≈ 31.8% and FEC2H4 ≈ 29.6%, respectively. The C2H4 selectivity was comparable to that of many reported Cu-based electrocatalysts at similar overpotentials. Furthermore, the FE for C2H4 remained stable even after 6 h of continuous electrolysis. The superior ECR activity of Cu/CeO2(110) to yield C2H4 was attributed to the metastable (110) surface, which not only promoted the effective adsorption of CO2 but also remarkably stabilized Cu+, thereby boosting the ECR to produce C2H4. This work offers an alternative strategy to enhance the ECR efficiency by crystal facet engineering. 相似文献
10.