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Search Results: 1 - 10 of 42559 matches for " CHANG Ai-Min "
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Preparation and Thermal Sensitive Characteristics of the Co0.8Mn0.8Ni0.9Fe0.5O4 Nanometer Powders
ZHANG Dong-Yan,ZHANG Hui-Min,JIN Xian-Jing,CHANG Ai-Min
无机材料学报 , 2009, DOI: 10.3724/sp.j.1077.2009.01008
Abstract: Nano-powders of Co0.8Mn0.8Ni0.9Fe0.5O4 NTC (Negative Temperature Coefficient) thermistor materials were prepared by co-precipitation method with NH4HCO3 as precipitator. The effects of calcination temperature on the material phase were studied. The influences of different sintering processes on the microstructure and thermal sensitive characteristics of NTC thermistor materials were investigated. The samples were characterized by XRD, TG/DTA, FT-IR, SEM, and Laser Particle Size Analyzer. The results show that the powders calcined at 750 re single spinel, the grain size of the powders is about 32.1nm, and the particle size is about 50-100nm. The samples possess better electrical properties: | SUB>25 亯SUB>=1183| ¤cm, B25/50=3034K under the process conditions of constant temperature 840 nd 1200 or 2h respectively, the heating and cooling rate of 1 in. It is found that proper sintering process can effectively improve the microstructure and thermal sensitive properties of the NTC thermistor materials. According to the calculation from the slope of ln| 1/T curves, the activation energy is about 0.26eV.
Preparation and Microwave Sinterability of Mn0.43Ni0.9CuFe0.67O4 NTC Thermistor Materials by Pechini Method
JIN Xian-Jing,CHANG Ai-Min,ZHANG Hui-Min,ZHANG Dong-Yan
无机材料学报 , 2009, DOI: 10.3724/sp.j.1077.2009.01013
Abstract: In order to obtain the NTC thermistors with small B constant (about 1900K), applied to wide temperature range, Mn0.43Ni0.9CuFe0.67O4 NTC thermistor materials prepared by Pechini method were microwave-calcined at different temperatures (650 750 nd 850 The calcined Mn0.43Ni0.9CuFe0.67O4 powders were pressed and then sintered at 1000 n a microwave furnace (multimode cavity, 2.45GHz).The crystal structure, phase compositions, morphology and particle size distribution of the samples were analyzed by FT-IR, X-ray diffraction (XRD), scanning electron microscope (SEM) and a laser particle size analyzer. The experimental results show that the electrical properties of the ceramics are strongly dependent on the calcination and sintering process. The application of microwave leads to a lower calcination temperature (650 and densified uniform microstructures. Microwave sintering can obtain the components with well uniformity of B constant and resistivity, of which the Bavg. is 1930K (deviation of 0.31%) and resistivity | SUB>avg. is 135| ¤cm (deviation of 4.55%). However, the Bavg. is 1720K (deviation of 1.47%) and resistivity |Сvg. is 78| ¤cm (deviation of 25.34%) for the conventionally sintered components. From complex impedance analysis, the grain resistance (Rb) and grain boundary resistance (Rgb) are respectively 255| and 305| for the microwavea2sintered samples. The Rb and Rgb are respectively 200| and 230| for conventionally sintered samples.
Chang-Bin Guo,Ri-Cai He,Ai-Min Li
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812027602
Abstract: In the title compound, C33H38N4O3, the mean planes of the 9H-xanthene unit and spirolactam (nine-atom) core are almost mutually perpendicular at 87.26 (6)°. Intramolecular N—H...O and C—H...N interactions influence the 4-oxopent-2-en-2-ylamino conformation. In the crystal, weak C—H...O hydrogen bonds link the molecules into chains along [001].
One-step Self Assemble of Cu-TiO2 Heterogeneous Nanoparticles Using a Soft Template
ZHAO Peng-Jun, WU Rong, HOU Juan, CHANG Ai-Min, GUAN Fang, ZHANG Bo
无机材料学报 , 2012, DOI: 10.3724/sp.j.1077.2012.12188
Abstract: Cu-TiO2 heterostructure nanoparticles were successfully synthesized via a novel one-step self-assemble hydrothermal method using polyethylene glycol as the soft template. The nanospheres were characterized in light of the chemical composition and morphology using X-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. The products are composed of cubic copper and anatase TiO2. Interfaces between Cu (101) and TiO2 (111) were observed by HRTEM. In addition, the nanoparticles size could be controlled by adjusting the polymerization degrees of PEG. The accommodations of the particle sizes were mainly caused by Cu nanospheres rather than TiO2. A possible synthetic mechanism which interprets the formation of Cu-TiO2 heterogeneous nanoparticles could be ascribed to the hydrogen bonds between Cu(NH3)2+ and PEG. UV-Vis absorption spectra indicated that the prepared product has strong absorbency in the visible region. Therefore, the unique interface nanomaterial could be used as a potential class of the materials platform as visible-light-driven photocatalyst and electrode on enhancing the photoelectric properties of solar cells.
Existence of Global Solutions of Higher-Order Semilinear Parabolic Equations
CHEN Ai-min
Journal of Chongqing Normal University , 2010,
Abstract: The existence of global solution to the following Cauchy problem for the higher-order semilinear parabolic equation is studied in this paper:**, where p >1+2m/n and m is a positive integer, First, the problem is transformed into an equivalent integral equation, then another integral equation, whose solution can control the solution of the equivalent integral equation, is constructed by introducing a self-similar kenel function. Finally, the boundedness of the equivalent integral equation can be obtained by proving the boundedness of the integral equation structured. Thus, if **,the solution of the problem is global , Besides, if lim inf **,then using the definition of the weak solution and the compactness of test function, the negative part of the weak solution can not be ignored with respect to the positive part.(* Indicates a formula, please see the full text)
Microstructure and Electrical Properties of Mn2.25―xNi0.75CoxO4 Thermistor Ceramics
PENG Chang-Wen, ZHANG Hui-Min, CHANG Ai-Min, HUANG Xia, YAO Jin-Cheng
无机材料学报 , 2011, DOI: 10.3724/sp.j.1077.2011.01037
Abstract: A series of composite of the negative temperature coefficient (NTC) powders of Mn2.25―xNi0.75CoxO4 (0.8≤x≤1.2) materials were prepared via solid―state method. The particle size of calcined powders, ceramics phase structure, morphology and electrical properties were characterized by laser particle size analyzer, XRD, SEM and electrical measurements, respectively. The results show that when the Mn2.25―xNi0.75CoxO4 ceramics sintered at 1130―1230 their characteristic parameters B25/50 value are found to be in the range of 3487K to 4455K and their electrical resistivities ρ25 re 1998 Ω·cm to 203617 Ω·cm. The B25/50 value and ρ25 irst increases and then decreases as the Co content increases. This means that electrical resistivity and B value of Mn2.25―xNi0.75CoxO4 ceramics could be adjusted to the desired values and this ternary system can be considered as the advanced semi―conducting materials for NTC thermistor applications.
Preparation and Thermal Sensitive Characteristics of the Co0.8Mn0.8Ni0.9Fe0.5O4 Nanometer Powders
Co0.8Mn0.8Ni0.9Fe0.5O4 纳米粉体的制备及热敏特性研究

ZHANG Dong-Yan,ZHANG Hui-Min,JIN Xian-Jing,CHANG Ai-Min,

无机材料学报 , 2009,
Abstract: 采用共沉淀法,以NH4HCO3为沉淀剂制备了Co0.8Mn0.8Ni0.9Fe0.5O4 负温度系数(NTC)热敏电阻纳米粉体材料, 研究了不同预烧温度对材料相结构的影响, 探讨了不同烧结工艺对NTC热敏电阻材料微观结构和热敏性能的影响. 采用X射线衍射(XRD)、综合热分析(TG/DTA)、红外(FT-IR)、扫描电子显微技术(SEM)和激光粒度分析仪对制备的样品进行了表征. 结果表明, 750℃预烧后的粉体为纯尖晶石相, 晶粒粒度为32.1nm, 颗粒粒径在50~100nm范围内. 通过对不同烧结程序的对比研究发现, 当烧结程序为:840℃、1200℃各保温2h, 升降温速率为1℃/min时, 样品电学性能较好:ρ25℃=1183Ω·cm, B25/50=3034K. 分析表明, 该烧结程序能有效改善热敏电阻材料的微观结构和热敏性能. 根据ln ρ-1/T曲线斜率计算了经不同工艺烧结后热敏电阻材料的激活能在0.26eV左右.
Development of High-K Gate Dielectric Materials
WU De-Qi,ZHAO Hong-Sheng, YAO Jin-Cheng, ZHANG Dong-Yan, CHANG Ai-Min
无机材料学报 , 2008,
Abstract: The traditional gate dielectric material of SiO2 can not satisfy the need of the continuous downscaling of CMOS dimensions. High-K gate dielectric materials have attracted extensive research efforts recently and obtained great progress. In this paper, the developments of high gate materials were reviewed. Based on the authors background and research work in the area, the latest achievements of high-K gate dielectric materials on the recrystalization temperature, the low-K interface layer, and the dielectric breakdown and metal gate electrode were introduced in detail.
Preparation of Fine Ceramic Ba0.65Sr0.35TiO3 Materials and Their Dielectric Properties

YANG Wen,CHANG Ai-Min,ZHUANG Jian-Wen,YANG Bang-Chao,

无机材料学报 , 2002,
Abstract: 采用溶胶-凝胶工艺制备了Ba0.65Sr0.35TiO3粉体,并利用微波烧结技术对粉体进行了合成和烧结,研究分析了样品的介电特性,并与传统制备工艺获得的样品进行了性能比较。实验结果表明,获得的Ba0.65Sr0.35TiO3粉体颗粒较细,其合成温度和烧结成瓷温度都较传统工艺有大幅度降低,分别为900和1310℃;可以获得晶粒尺寸在1μm以内的陶瓷;随晶粒的减小,材料的相对介电常数变化不大,而介电损耗大大降低。
MgAl2O4-LaCrO3 Insulator Materials for the Microwave Sintering of Electronic Oxide Ceramics

CHANG Ai-Min,YANG Wen,JIAN Jia-Wen,LI Yan-Rong,

无机材料学报 , 2002,
Abstract: 报道了一种用于氧化物电子陶瓷微波烧结的保温体材料MgAl2O4 LaCrO3的研究和应用情况。该保温材料解决了许多氧化物电子陶瓷在微波烧结过程中易发生的热应力开裂问题并同时具有使样品均匀烧结成瓷的作用。现已成功地应用该保温体对CnMnNiO系NTC热敏材料,BaTiO3系PTC材料,ZnO掺杂系电压敏材料,LaCrO3基复合材料等氧化物电子陶瓷进行了微波烧结,烧结样品无热应力开裂并成瓷均匀致密。适用的氧化物电子陶瓷微波烧结温度区间最高可至1600℃。
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