共查询到19条相似文献,搜索用时 78 毫秒
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利用Mindlin板理论分析了硅酸镓镧晶体板强耦合的厚度剪切振动和弯曲振动,获得了硅酸镓镧晶体板高频振动的色散关系、频谱关系和振动模态位移图。数值计算结果表明,Mindlin板理论可以获得硅酸镓镧晶体板厚度剪切振动的一阶精确截止频率,无需修正系数。基于石英晶体谐振器设计晶片最佳长厚比的选取方法,确定了硅酸镓镧晶片的最佳尺寸,避免了厚度剪切振动模态和弯曲振动模态的强耦合。通过绘制硅酸镓镧晶体板在最佳尺寸时的各振动模态位移图,发现厚度剪切振动模态是主振模态,具有很好的能陷效应。Mindlin板理论在硅酸镓镧晶体板高频振动的应用分析可以指导硅酸镓镧晶体谐振器的实际研发。 相似文献
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声表面波射频识别标签在射频标签领域获得广泛关注,其中对标签基底材料的研究也成了研究热点。文章旨在研究使用硅酸镓镧单晶材料为压电基底的声表面波标签的标签特性。对使用硅酸镓镧单晶材料为压电基底的声表面波标签进行频域和时域分析,并结合有限元分析方法,对标签的特征频率、叉指换能器(Interdigital Transducer, IDT)的反射系数、叉指电极金属化比、金属电极厚度以及标签回波特性进行研究分析,提取了耦合模COM(Coupled-mode)模型参数。分析结果表明了压电效应是声表面波的谐振与反谐振频率存在的根源,验证了脉冲幅度编码方式,并为使用硅酸镓镧材料作为压电基底的声表面波标签的制作提供了仿真实验依据。 相似文献
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用全息干涉法研究了新型压电材料硅酸镓镧的折射率均匀性,利用干涉透过率谱法研究了双折射率.并通过测量透过率,计算了吸收系数.确定了吸收系数与光子能量的变化关系. 相似文献
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磷灰石结构硅酸镧具有优良的氧离子导电性和化学稳定性,有望作为新一代中低温固体氧化物燃料电池电解质.综述了磷灰石结构硅酸镧的结构特征及导电机理,探讨了La位和Si位不同元素掺杂对硅酸镧电解质电导率的影响.概述了固相反应法、溶胶-凝胶法、凝胶-注模法、共沉淀法、熔融盐法合成硅酸镧的现状,指出了硅酸镧作为固体氧化物燃料电池电解质仍存在的问题及今后的发展方向. 相似文献
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β-Ga2O3作为新型宽禁带半导体材料,近年来受到了人们的广泛关注。β-Ga2O3禁带宽度可达4. 7 e V,相比于第三代半导体SiC和Ga N,具有禁带宽度更大、击穿场强更高、Baliga品质因子更大、吸收截止边更短、生长成本更低的优点,有望成为高压、大功率、低损耗功率器件和深紫外光电子器件的优选材料。此外,β-Ga2O3单晶可以通过熔体法生长,材料制备成本相对较低,有利于大规模应用。重点介绍了β-Ga2O3单晶的生长及工艺优化,然后对晶体加工、性能表征、光电探测及功率器件应用等方面进行了讨论,并展望了β-Ga2O3晶体未来的发展方向。 相似文献
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Bing TENG Weijin KONG Ke FENG Fei YOU Lifeng CAO Degao ZHONG Lun HAO Qing SUN Sander van SMAALEN Wenhui GONG 《材料科学前沿(英文版)》2015,9(2):147
A new organic crystal of 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium benzene sulfonate (DASBS) was synthesized and characterized for the first time. It is a derivative of 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) with the benzene sulfonate replacing p-toluenesulfonate. Single crystal XRD demonstrated that the crystal structure of DASBS·H2O was triclinic. The thermal analysis of this new crystal was also conducted, and the melting point was obtained to be 232°C. 相似文献
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外尔半金属是当两个自旋非简并能带在三维动量空间通过费米能级附近时,其低能准粒子激发具有外尔费米子的所有特征的一类材料体系。外尔费米子是狄拉克方程的无质量解,可以看作是在三维空间一对重叠在一起且具有相反手性的粒子。TaAs单晶作为一种非磁性的外尔半金属,在其中能够观测到外尔费米子,并产生许多奇异的物理现象,如费米弧、负磁阻效应、量子反常霍尔效应等,使其在发展新型电子器件和拓扑量子计算等领域有着重要应用潜力。介绍了外尔半金属的相关基础理论和重要实验,重点探讨了TaAs单晶生长相关的技术问题,分析了化学气相传输法的优缺点。 相似文献
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The analysis of crack growth in magnesium single crystal was performed using molecular dynamics simulation with Embedded Atom Method (EAM) potentials. The twinning process at the crack tip was analyzed. Four specimens with increasing sizes were used to investigate the influences of material length scale on crack growth of magnesium single crystals. Furthermore, the effects of temperature, and the loading strain rate were also verified. The specimens were subjected to uniaxial tension strain up to the total strain level of 0.2 with a constant strain rate. In the simulation of each specimen, the averaged stress strain curve was monitored. The simulation results show that the specimen size, loading strain rate, and temperature strongly influence the peak stress point at which the twin nucleated and subsequently the crack grew. The initial slope of the averaged stress strain curve is independent of the loading strain rate and temperature. Moreover, high temperatures induce increased atomic mobility, and thereby atom reorganization, which, in turn, releases the stress at the crack tip. 相似文献
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Yeshun Huang Xinguang Wang Chuanyong Cui Zihao Tan Jinguo Li Yanhong Yang Jinlai Liu Yizhou Zhou Xiaofeng Sun 《材料科学技术学报》2021,69(10):180-187
The effect of thermal exposure on microstructure and creep properties of a fourth-generation nickelbased single crystal superalloy was investigated.The thermal exposure of samples after the full heat treatment was carried out at 1000℃,1100℃ and 1140℃ for 100 h and 200 h.The γ' coarsening,γ' rafting and γ channel widening were observed in samples after thermal exposure.When the thermal exposure time was constant,the morphology of γ' phase in the alloy evolved significantly with increasing aging temperature.The interracial dislocation networks in aged samples after creep ruptured gradually became irregular and sparse with the increase of exposure temperature.When the higher exposure temperature was used,enla rgement of the defect pores was observed in samples,the microcracks were more likely to initiate and propagate at the corner of these pores.After aging at 1000℃ for 100 h,the creep life at 1140℃/137 MPa was slightly longer than that of heat-treated sample,which could be attributed to the slightly coarsened γ' phase,homogenization of refractor elements.In contrast,the creep life of sample exposed at 1140℃ for 100 h was greatly decreased.The decrease of creep life was dominated by the rafting of γ'phase,the irregular interfacial dislocation networks as well as the enlargement of homogenization pores. 相似文献
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镍基单晶高温合金研究进展 总被引:1,自引:0,他引:1
单晶高温合金因具有较高的高温强度、优异的蠕变与疲劳抗力以及良好的抗氧化性、抗热腐蚀性、组织稳定性和使用可靠性,广泛应用于涡轮发动机等先进动力推进系统涡轮叶片等部件。由于采用定向凝固工艺消除了晶界,单晶高温合金明显减少了降低熔点的晶界强化元素,提高了合金的初熔温度,能够在较高温度范围进行固溶和时效处理,其高温强度比等轴晶和定向柱晶高温合金也大幅度提高。经过几十年的发展,单晶高温合金已经在合金设计方法、组织结构与力学性能关系、纯净化冶炼工艺和定向凝固工艺等方面取得了重要进展。从单晶高温合金成分特点、合金元素作用、强化机理、力学性能各向异性、凝固过程及缺陷控制、单晶制备工艺等方面,简要介绍了单晶高温合金的主要研究进展。 相似文献