共查询到20条相似文献，搜索用时 187 毫秒
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CaCu_3Ti_4O_(12)(CCTO)是近年被广泛关注的一种非铁电性的新型高介电氧化物,采用传统的固相反应,通过对反应温度和恒温时间的组合,成功制备了巨介电常数陶瓷CaCu_3Ti_4O_(12)样品,并对其合成温度,微观结构,烧结温度与微观结构关系,介电频谱进行分析。 相似文献
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采用化学共沉淀法和溶胶凝胶法制备BaTiO3-CoFe2O4两相复合陶瓷粉体,并通过成型1200℃烧结制备BaTiO3-CoFe2O4两相复合陶瓷,测试XRD和TEM,并对其介电,漏电,铁电进行了研究。XRD分析制备的BTO陶瓷为四方结构,铁电性较好,具有较大的介电常数和较低的介电损耗,CFO陶瓷为尖晶石结构,复合陶瓷具有两相结构,同时具有铁电性和磁性。 相似文献
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利用传统固相烧结法制备功能介电陶瓷材料CaSrTiMnO6(CSTM).里瓦尔德精修结果表明,该陶瓷具有单钙钛矿结构,属于pnma空间群.在CSTM陶瓷的介电谱图中,只出现了一个介电弛豫峰,本文利用混价结构机理和归一化键长理论很好地解释了这种现象.在333～453 K的温度区间内,介电常数在低频下稳定地保持在4 000左右.这种性质说明该陶瓷材料在高温低频下具有很大的实际应用潜力. 相似文献
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本文研究了熔盐法合成的PMN-PT粉末的烧结特性,以及合成工艺对PMN-PT陶瓷致密度,显微结构和介电性能的影响.结果显示,熔盐合成的粉料具有较小的颗粒尺寸和良好的分散性,能够降低陶瓷的烧结温度,在1150～1180℃范围烧结可得到致密度≥96%的PMN-PT陶瓷.在1100～1200℃烧结温度范围,硫酸盐熔盐体系制备的陶瓷呈沿晶断裂,而氯化物熔盐体系制备的陶瓷均呈穿晶断裂.在相同的烧结温度下,氯化物熔盐制备的陶瓷的晶粒尺寸明显大干硫酸盐熔盐体系的陶瓷的晶粒尺寸.用熔盐法制备的组分为0.67PMN-0.33PT陶瓷具有优良的压电和介电性能.在1175℃/2h烧结条件下,制备的0.67PMN-0.33PT陶瓷的最大介电常数为29385,d33 ≈ 660pC/N. 相似文献
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本文研究了熔盐法合成的PMN-PT粉末的烧结特性，以及合成工艺对PMN-PT陶瓷致密度，显微结构和介电性能的影响。结果显示，熔盐合成的粉料具有较小的颗粒尺寸和良好的分散性，能够降低陶瓷的烧结温度，在1150～1180℃范围烧结可得到致密度≥96％的PMN-PT陶瓷。在1100～1200℃烧结温度范围，硫酸盐熔盐体系制备的陶瓷呈沿晶断裂，而氯化物熔盐体系制备的陶瓷均呈穿晶断裂。在相同的烧结温度下，氯化物熔盐制备的陶瓷的晶粒尺寸明显大于硫酸盐熔盐体系的陶瓷的晶粒尺寸。用熔盐法制备的组分为0．67PMN．0．33PT陶瓷具有优良的压电和介电性能。在1175℃／2h烧结条件下，制备的0．67PMN-0．33PT陶瓷的最大介电常数为29385，d33≈660pC／N。 相似文献
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研究了中温烧结的BaO—TiO2～Nd2O3系陶瓷的介电性能。实验结果表明,在这一系统中分别或联合掺入适量的PbO、Bi2O3、CuO、V2O5、2Bi203·3TiO2和Bi2O3·2TiO2可以降低系统的烧结温度,拓宽烧成温度范围,并有助于改善介电性能,增大介电常数,从而得到了介电性能优良的高频陶瓷材料。 相似文献
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纳米钛酸钡的研究进展 总被引：2，自引：0，他引：2
钛酸钡具有高介电常数和低介电损耗,优良的铁电、压电、耐压和绝缘性能,广泛地应用于制造陶瓷敏感元件、多层陶瓷电容器（MLCCS）、记忆材料等。随着纳米技术的发展和对钛酸钡材料性能要求的提高,纳米碳酸钡的研究获得了很大的发展。本文介绍了纳米钛酸钡的主要性质和应用领域,对纳米钛酸钡制备方法的研究进展进行了综述,并分析了其发展趋势。 相似文献
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BNT无铅压电陶瓷体系的设计及制备工艺研究 总被引：1，自引：0，他引：1
本文采用传统陶瓷工艺,制备得到Bi0.5(Na1-x-yKxLiy)0.5TiO3(简称BNKLT)无铅压电陶瓷,运用X射线衍射、扫描电子显微镜对其进行了分析表征;通过压电、介电性能的对比,讨论了烧结温度对BNKLT陶瓷的影响:运用热分析及X射线衍射等手段,确定了粉体的热处理温度,并讨论了烧结温度对BNKLT陶瓷性能的影响;通过最终所得陶瓷的性能对比,确定制备的较优工艺参数. 相似文献
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相对介电常数不仅广泛地使用于电磁学、电工学等与电相关的领域中,而且在工程技术中也是十分重要的物理参数,测量相对介电常数成为物理实验及其科学研究中的重要内容之一.通过自制仪器测量土豆片样品置入平行板电容器对其电容量影响的结果,从而推导出土豆片的相对介电常数. 相似文献
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简要评述了陶瓷基板,微波介质陶瓷,铁电压电陶瓷,半导体陶瓷,铁电薄膜和智能材料等功能陶瓷的研究进展和发展趋势,对我院功能陶瓷的发展提出了一些建议。 相似文献
12.
闪锌矿型CdTe电子结构和光学性质的第一性原理 总被引：4，自引：0，他引：4
采用基于密度泛函理论(DFT)框架下广义梯度近似平面波超软赝势法,计算了闪锌矿型CdTe的能带结构、态密度和光学性质.计算表明,闪锌矿型CdTe为直接带隙半导体,禁带宽度为0.671eV.计算并分析了闪锌矿型CdTe的复折射率、复介电函数、吸收系数、光电导率、损失函数和反射率,其折射率为2.69,静态介电常数为7.23.计算结果与其他文献结果吻合较好,为闪锌矿型CdTe的应用提供了理论依据. 相似文献
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简述了数据、图像、声音传输设备中数据线的重要性,分析了当前数据、图像、声音传输设备中数据芯线的缺陷,要达到高频、高速、低衰减的传输要求,唯有降低数据线芯线的介电常数和介电损耗,重点阐述了双层复合PE发泡芯线的材料、结构及性能,从而满足高频、高速、低衰减的传输要求。 相似文献
14.
The dielectric properties of tumour cells are known to differ from normal blood cells, and this difference can be exploited for label-free separation of cells. Conventional measurement techniques are slow and cannot identify rare circulating tumour cells (CTCs) in a realistic timeframe. We use high throughput single cell microfluidic impedance cytometry to measure the dielectric properties of the MCF7 tumour cell line (representative of CTCs), both as pure populations and mixed with whole blood. The data show that the MCF7 cells have a large membrane capacitance and size, enabling clear discrimination from all other leukocytes. Impedance analysis is used to follow changes in cell viability when cells are kept in suspension, a process which can be understood from modelling time-dependent changes in the dielectric properties (predominantly membrane conductivity) of the cells. Impedance cytometry is used to enumerate low numbers of MCF7 cells spiked into whole blood. Chemical lysis is commonly used to remove the abundant erythrocytes, and it is shown that this process does not alter the MCF7 cell count or change their dielectric properties. Combining impedance cytometry with magnetic bead based antibody enrichment enables MCF7 cells to be detected down to 100 MCF7 cells in 1 ml whole blood, a log 3.5 enrichment and a mean recovery of 92%. Microfluidic impedance cytometry could be easily integrated within complex cell separation systems for identification and enumeration of specific cell types, providing a fast in-line single cell characterisation method. 相似文献
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The present work aims to study the effects of the blood-microstructure on the electrical conduction from two different but correlated properties: Electrical and mechanical (viscosity), and to derive useful parameters for the evaluation of electrical conduction as a function of the blood viscosity. ac-conductivity and dielectric constant of normal and diabetic blood are measured in the frequency range 10 kHz–1 MHz at the room temperature. An empirical relation relating the resistivity and viscosity of the blood has been presented. The results show that a microfluidic device is a viable and simple solution for determination of electrical and rheological behaviors of blood samples. 相似文献
16.
Dielectrophoretic properties of DNA have been determined by measuring capacitance changes between planar microelectrodes. DNA sizes ranged from 100 bp to 48 kbp, DNA concentrations from below 0.1 to 70 μg∕ml. Dielectrophoretic spectra exhibited maximum response around 3 kHz and 3 MHz. The strongest response was found for very long DNA (above 10 kbp) and for short 100 bp fragments, which corresponds to the persistence length of DNA. The method allows for an uncomplicated, automatic acquisition of the dielectrophoretic properties of submicroscopical objects without the need for labeling protocols or optical accessibility. 相似文献
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Sangjo Shim Katherine Stemke-Hale Jamileh Noshari Frederick F. Becker Peter R. C. Gascoyne 《Biomicrofluidics》2013,7(1)
The number of circulating tumor cells (CTCs) found in blood is known to be a prognostic marker for recurrence of primary tumors, however, most current methods for isolating CTCs rely on cell surface markers that are not universally expressed by CTCs. Dielectrophoresis (DEP) can discriminate and manipulate cancer cells in microfluidic systems and has been proposed as a molecular marker-independent approach for isolating CTCs from blood. To investigate the potential applicability of DEP to different cancer types, the dielectric and density properties of the NCI-60 panel of tumor cell types have been measured by dielectrophoretic field-flow fractionation (DEP-FFF) and compared with like properties of the subpopulations of normal peripheral blood cells. We show that all of the NCI-60 cell types, regardless of tissue of origin, exhibit dielectric properties that facilitate their isolation from blood by DEP. Cell types derived from solid tumors that grew in adherent cultures exhibited dielectric properties that were strikingly different from those of peripheral blood cell subpopulations while leukemia-derived lines that grew in non-adherent cultures exhibited dielectric properties that were closer to those of peripheral blood cell types. Our results suggest that DEP methods have wide applicability for the surface-marker independent isolation of viable CTCs from blood as well as for the concentration of leukemia cells from blood. 相似文献
19.
张俊才 《科技成果管理与研究》2011,(10):45-47
以粉煤灰为主要原材料,采用熔融一烧结法制备了不同Na／Ca比的微晶玻璃材料。用差示扫描量热分析方法分析了基础玻璃的热性质并制定了微晶玻璃的烧结制度。用X射线衍射分析了微晶玻璃样品的晶相组成,用光学显微镜分析了样品的组织形貌,测试了微晶玻璃的显微硬度,并讨论了不同Na／Ca比对粉煤灰微晶玻璃的晶相组成、形貌及性能的影响。结果表明随着Na／Ca比的减小,样品显微硬度值呈上升趋势。 相似文献
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Dielectric breakdown is a common problem in a digital microfluidic system, which limits its application in chemical or biomedical applications. We propose a new fabrication of an electrowetting-on-dielectric (EWOD) device using Si3N4 deposited by low-pressure chemical vapor deposition (LPCVD) as a dielectric layer. This material exhibits a greater relative permittivity, purity, uniformity, and biocompatibility than polymeric films. These properties also increase the breakdown voltage of a dielectric layer and increase the stability of an EWOD system when applied in biomedical research. Medium droplets with mouse embryos were manipulated in this manner. The electrical properties of the Si3N4 dielectric layer—breakdown voltage, refractive index, relative permittivity, and variation of contact angle with input voltage—were investigated and compared with a traditional Si3N4 dielectric layer deposited as a plasma-enhanced chemical vapor deposition to confirm the potential of LPCVD Si3N4 applied as the dielectric layer of an EWOD digital microfluidic system. 相似文献