共查询到19条相似文献,搜索用时 93 毫秒
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采用凝胶注模工艺制备出了Al2O3/Ba0.6Sr0.4TiO3复相陶瓷坯体.重点研究了料浆的流变学特性和凝胶化机理.研究表明,Al2O3/Ba0.6Sr0.4TiO3复相陶瓷水基料浆呈现“剪切变稀“行为,单体和交联剂含量和引发剂、催化剂的加入量都对固化速度有着直接的影响.在对Al2O3/Ba0.6Sr0.4TiO3烧结体研究时发现:由于Ba0.6Sr0.4TiO3的加入,内部晶粒最终都形成规则的平面六角结构. 相似文献
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采用水基料浆注模凝胶法制备出了高质量的96%Al2O3瓷高压真空开关管壳。解决了高固相含量水基料浆的配制,注模凝胶化和脱模操作等问题。研究结果表明,其尺寸精度和表面质量良好,密度达到3.79g/cm^3,多项机电性能均超过产品技术要求。证实了水基料浆注模凝胶法制备高压真空开关管壳是一种新的低成本制备技术,值得推广应用。 相似文献
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针对纤维素气凝胶隔热性能差、易燃烧等问题,基于液氮定向冷冻及真空冷冻干燥技术,以低成本、环境友好的微晶纤维素为原材料,Al2O3-SiO2溶胶为阻燃剂,去离子水为溶剂,加入硼酸作为催化剂控制共水解进程,制备出隔热阻燃性能良好的Al2O3-SiO2/纤维素复合气凝胶。采用扫描电子显微镜、傅里叶变换红外光谱仪、热重分析仪、锥形量热仪等研究了Al2O3-SiO2溶胶含量对材料结构与性能的影响,并分析了复合气凝胶的阻燃机制。结果表明,随着Al2O3-SiO2溶胶含量的增加,Al2O3-SiO2/纤维素复合气凝胶从蜂窝状结构向多孔三维网络结构转变,孔径减小。Al2O3-SiO2溶胶与微晶纤维素溶液体积比为2... 相似文献
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采用射频磁控溅射法在蓝宝石基片上制备了Bi1.5Zn1.0Nb1.5O7(BZN)/Ba0.5Sr0.5TiO3(BST)双层复合薄膜,并研究了该薄膜在100 kHz~6 GHz频率范围内的介电性能。研究结果表明,BZN/BST复合薄膜的介电性能具有良好的频率稳定性。该复合薄膜的介电常数在研究的频率范围内基本与频率无关;其介电损耗在频率低于1 GHz时与频率无关,在频率高于1 GHz时随频率的上升而略微增大;薄膜在研究的频率范围内具有稳定的介电调谐率。 相似文献
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将6H-SiC和α-Al2O3以质量比7:3混合,添加质量分数0~10%的MgO-CaO作为烧结助剂,球磨后的粉体压制成生坯,在1 200℃预氧化1 h后在氢气氛下常压烧结1 h制备Al2O3-SiC复相材料。研究了烧成温度和MgO-CaO含量对该复相材料烧结性能和相组成的影响。结果表明:1 500℃下,随着烧结助剂含量的增加,烧结致密性明显提高,当烧结助剂质量分数为10%时,显气孔率降至0.1%。预氧化时,添加烧结助剂MgO-CaO,方石英和α-Al2O3与之反应,生成CaAl2Si2O8和Mg2Al4Si5O18,促进6H-SiC的进一步氧化。烧成过程中,CaAl2Si2O8和MgAl2O4溶解生成玻璃相促进烧结,同时α-Al2O3从玻璃相中析出,1 500℃烧结试样所含物相为6H-SiC和α-Al2O3。 相似文献
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将水基流延技术与低温烧结陶瓷技术相结合,用于BST挠曲电陶瓷的研制和能量的收集。为了降低BST的烧结温度,在BST水基流延浆料中添加了质量分数1%~4%的Li2CO3,将浆料流延成薄片后进行烧结。研究了Li2CO3掺杂量对烧结温度的影响以及BST薄片厚度对材料电性能的影响。实验结果表明,适量的Li2CO3掺杂能够将BST的烧结温度降低约250℃。在烧结后的薄片两面涂上银电极和适当厚度的PDMS,得到“三明治结构”的BST复合薄片,用于介电、挠曲电测试和能量收集实验。当Li2CO3掺杂量为质量分数2%时,300μm厚的BST复合薄片在1100℃烧结后介电性能最优,其介电常数为3200,介质损耗为0.05。而200μm厚的复合薄片表现出最高的横向挠曲电系数,达到0.24μC/m。此外,40μm厚的复合薄片表现出最好的电流输出能力,达到1.2 nA。 相似文献
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Acikel B. Taylor T.R. Hansen P.J. Speck J.S. York R.A. 《Microwave and Wireless Components Letters, IEEE》2002,12(7):237-239
In this paper, a new device topology has been proposed to implement parallel plate capacitors using BaxSr1-xTiO3 (BST) thin films. The device layout utilizes a single parallel capacitor and minimizes conductor losses in the base electrode. The new design simplifies the monolithic process and overcomes the problems associated with electrode patterning. An X-band 180° phase shifter has been implemented using the new device design. The circuit provided 240° phase shift with an insertion loss of only 3 dB at 10 GHz at room temperature. We have shown a figure of merit 93°/dB at 6.3 GHz and 87°/dB at 8.5 GHz. To our knowledge, these are the best figure of merit results reported in the literature for distributed phase shifters implemented using BST films at room temperature 相似文献
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Berge J.. Vorobiev A.. Steichen W.. Gevorgian S.. 《Microwave and Wireless Components Letters, IEEE》2007,17(9):655-657
Electrically tunable solidly mounted thin film bulk acoustic resonators based on BaxSr1-xTiO3 films are reported for the first time. The films are acoustically isolated from the silicon substrate by a Bragg reflector stack. Applying DC bias induces piezoelectric effect and an acoustic resonance at approximately 4 GHz. Under 10 V applied DC bias the resonance frequency of the resonators based on Ba0.25Sr0.75TiO3 films is tuned 1.2% to lower frequencies. The Q-factor of these resonators is approximately 120, and the electromechanical coupling coefficient is 0.5%. The resonant frequency of the BaTiO3 based resonators shifts upwards 1.3% under 10 V DC bias, and the -factor is approximately 30, with an electromechanical coupling coefficient of 6.2%. 相似文献
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以高纯的硫酸铝氨分解的无定形Al2O3为原料,MgO-Y2O3为烧结助剂,在N2气氛下热压烧结制备Al2O3陶瓷。研究了烧结助剂掺量对Al2O3材料的相组成、显微结构、烧结性能、力学性能、热导率和介电性能的影响。结果表明:所制Al2O3陶瓷具有细晶的显微结构特征和超高的抗弯强度。随着MgO-Y2O3掺量的增加,晶粒尺寸、抗弯强度和热导率先增大后减小,而介电损耗则呈现先减小后增大的变化规律。当MgO和Y2O3掺量均为质量分数2%时,Al2O3陶瓷呈现为较佳的综合性能:抗弯强度达最大值为603 MPa,热导率为36.47 W.m–1.K–1,介电损耗低至6.32×10–4。 相似文献
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Aluminium oxide displays a very low tanδ at microwave frequencies. It also possesses a remarkably high thermal conductivity, ideal for heat dissipation in high power satellite filters. However, its temperature coefficient of the resonant frequency (τf) is approximately 60 ppm/K. It is shown that the application of a film of titanium oxide which has a Tf of opposite sign (45O ppm/K) produces a composite in which the τf can be tuned to be zero over a wide temperature range. The tanδ of the composite at zero Tf is 3.3×105 (Q=30000) at room temperature and at 10 GHz 相似文献
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Zengfeng Di Miao Zhang Weili Liu Qinwo Shen Zhitang Song Chenglu Lin Anping Huang Paul K. Chu 《Materials Science in Semiconductor Processing》2006,9(6):959
The structural and electrical characteristics of a novel nanolaminate Al2O3/ZrO2/Al2O3 high-k gate stack together with the interfacial layer (IL) formed on SiGe-on-insulator (SGOI) substrate have been investigated. A clear layered Al2O3 (2.5 nm)/ZrO2 (4.5 nm)/Al2O3 (2.5 nm) structure and an IL (2.5 nm) are observed by high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy measurements indicate that the IL contains Al-silicate without Ge atom incorporation. A well-behaved C–V behavior with no hysteresis shows the absence of Ge pileup or Ge segregation at the gate stack/SiGe interface. 相似文献
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采用同轴送粉激光近净成形系统,在纯钛基体上进行激光近净成形(LENS)ZrO2-13%Al2O3(质量分数)复合陶瓷的基础实验研究。分析了激光功率和扫描速度对激光近净成形陶瓷薄壁宏观质量(宽高、表面平整性和宏观裂纹)的影响规律,获得致密、无宏观裂纹的陶瓷薄壁件。利用扫描电镜观察了成形件的微观组织,结合电子探针(EPMA)和X射线衍射仪(XRD)分析了微观组织成分和ZrO2陶瓷激光加工前后相成分的变化。结果表明,激光功率和扫描速度对激光近净成形陶瓷单层高度和表面宏观质量具有重要影响,通过精确控制该两个参数能够获得良好的表面质量;不同的激光功率和扫描速度下,会产生横向和纵向两种不同的宏观裂纹;激光近净成形技术能够制备出致密并具有细小枝状晶组织的陶瓷;少量的Al2O3主要存在于晶界中,有利于抑制裂纹扩展。 相似文献
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The process for generating nanocomposite films constructed from alternate thin film layers of Ba0.5Sr0.5TiO3 and PbZr0.48Ti0.52O3 by photochemical metal–organic deposition and sol-gel has been investigated. By spin coating the appropriate metal organic precursors to Ba0.5 Sr0.5TiO3 followed by photolysis a single layer of amorphous Ba0.5Sr0.5TiO3, is produced. Subsequent spin coating of the appropriate metal organic precursors of PbZr0.48Ti0.52O3 and photolysis led to the formation of a layer of amorphous PbZr0.48Ti0.52O3. By repeating this procedure a material composed of alternating layers of BST and PZT was constructed. In an analogous process alternate coating and heating of the appropriate sol-gel precursors was used to make similar structures. These nanocomposite materials were formed as amorphous layered materials but could be made to crystallize by heat treatment. Heat treatment resulted in crystallization of the films although the resultant diffraction pattern was dependent upon the thickness of the layers. X-ray diffraction patterns of both BST and PZT were apparent in crystalline films formed from layers of more than 25 nm in thickness. The crystallization of films formed from layers less than 25 nm in thickness showed only a lattice constant intermediate between that expected for BST and PST consistent with the interdiffusion of these components. Atomic force microscopy indicated that the amorphous nanocomposite films were near featureless while the crystalline films had a much higher surface roughness. 相似文献