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Valence Distribution in AT_xV_(6-X)O_(11) Compounds

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Journal of Materials Science & Technology 1999年第6期15卷 551-554页

作者： Hongchao LIU and Changlin KUO(shanghai institute of ceramics, Chinese Academy of Sciences, shanghai 200050, China) shanghai institute of ceramics Chinese Academy of Sciences Shanghai 200050 China

The distribution of trivalent and tetravalent cations in several ATxV6-xO11 compounds was quantitatively studied by the bond valence method. In SrV6O11, the M(3) sites were mainly occupied by trivaient cations; while M(1) and M(2) sites were shared by trivalent and tetravalent cations, the relative content of tetravalent at M(1) sites was higher than at M(2) sites. During substitution process, the trivalent cations preferred to occupy M(3) sites, tetravalent ones preferred to occupy M(2) sites. The occupancy of trivalent and tetravalent cations at M sites would change with the substitution

关键词： AT X)O Valence Distribution in AT_xV Compounds

X-ray Powder Diffraction Pattern of Bi_4(SiO_4)_3

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Journal of Materials Science & Technology 1997年第2期13卷 145-148页

作者： Hongchao LIU Changlin KUO (shanghai institute of ceramics, Chinese Academy of Sciences, shanghai 200050, China) shanghai institute of ceramics Chinese Academy of Sciences Shanghai 200050 China

In cooperation with figure-of-merits the Rietveld analysis can appraise both angular and intensity data of powder diffraction. In this work, X-ray diffraction pattern of Bi4(SiO4)3 was redetermined with intensity figure-of-merits, which qualify agreement between observed and calculated relative intensities. F30 is 158.90 (0.0059, 32), intensity figure of merit Rint is 8.7, I20(17), 8.0. The values of figure-of-merits show that the data of JCPDS cards are distorted. Both the experimental and calculated peak positions and heights are listed in detail.

关键词： SiO4 X-ray Powder Diffraction Pattern of Bi4 Bi

Removal Behaviors of Different SiC ceramics during Polishing

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Journal of Materials Science & Technology 2010年第2期26卷 125-130页

作者： Guiling Liu, Zhengren Huang , Xuejian Liu and Dongliang Jiang Structural ceramics Center, shanghai institute of ceramics, Chinese Academy of Sciences, shanghai 200050, China Structural ceramics Center Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China

Comparative experiments were conducted to reveal the removal behaviors of three kinds of silicon carbide （SIC） ceramics during polishing and the effects of ceramic microstructure on the surface quality were also reported. Experimental results show that the second phase in SiC ceramics plays an important role in the surface quality when its size is large enough. The surface quality is enslaved to the formation of steps at interfaces between second phase and SiC matrix that results from different elastic modulus and hardness between two phases. Under 3 μm abrasive grains polishing condition, different SiC ceramics show different removal mechanisms. With decreasing abrasive grain size, all of different SiC ceramics exhibit a ductile removal mode, which decreases surface roughness efficiently.

关键词： SiC Surface quality Removal behavior Polishing

Formation and Oxidation Resistance of Silicide Coatings for Mo and Mo-Based Alloys

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Journal of Materials Science & Technology 2001年第4期17卷 479-481页

作者： Yu WANG , Yunpeng LI and Xingfang HU shanghai institute of ceramics, Chinese Academy of Sciences, shanghai 200050, China shanghai Inst. of ceramics Chinese Acad. of Sci. Shanghai 200050 China

The forming process of silicide coatings on pure Mo and Mo-base alloys, obtained by the gas- phase deposition method. has been studied by examining the microstructure of coatings and the relationship between coating thickness and process parameters. It was shown that the growth of coatings was diffusion-controlled, the diffusion of silicon to be coated into Mo or Mo-base alloys was mainly responsible for the formation of silicide. The relationship between initial silicide thickness and oxidation resistance was also investigated, and the equation of service life of the coatings at high temperature in air is presented.

关键词： Mo Formation and Oxidation Resistance of Silicide Coatings for Mo and Mo-Based Alloys

Blue-shift of Nano-Y_2O_3 : Eu^(3+) Emission Spectra Excited by X-ray

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Journal of Materials Science & Technology 1997年第4期13卷 351-353页

作者： Qiang LI Lian GAO and Dongsheng YAN(State Key Lab. of High Performance ceramics & Superfine Microstructure, shanghai institute of ceramics,Chinese Academy of Sciences, shanghai 200050, China) State Key Lab. of High Performance ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China

Nano-Y_2O_3:Eu^(3+) powder was prepared by the homogeneous precipitation. With controlling the conditions of the reaction, nano powders with different grain size were obtained. It is found that the blue-shift phenomena exist in the nano-Y2O3:Eu3+ emission spectra excited by X-ray. The wave lengths of the peak (5D0→7F2) are related with the grain size of the powder

关键词： Eu Nano Emission Spectra Excited by X-ray Blue-shift of Nano-Y2O3

Preparation and Properties of Nano-TiO_2 Powders

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Journal of Materials Science & Technology 1997年第4期13卷 321-323页

作者： Zhe SONG Qing LI and Lian GAO(State Key Lab. of High Performance ceramics & Superfine Microstructure, shanghai institute of ceramics,Chinese Acadmey of Sciences, shanghai 200050, China) State Key Lab. of High Performance ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Acadmey of Sciences Shanghai 200050 China

This paper reports the preparation of nano-TiO2 (about 10 nm) powder by the method of precipitation. In detail, some breparation conditions were investigated in order to find out how to control the grain size and reduce the agglomeration of powders. Also, the reflex spectra of nano-scale powders with different grain size were studied. It tvas found that the wave length and width of reflex spectra are connected with the grain size of nano-TiO2 powders

关键词： TiO Nano Preparation and Properties of Nano-TiO2 Powders OC

Densification and Microstructure of β-sialon/Nano-size SiC Composites

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Journal of Materials Science & Technology 1997年第4期13卷 339-341页

作者： Cheng ZHANG Danyu JIANG Qiang LI and Weiying SUN (shanghai institute of ceramics, Chinese Academy of Sciences, shanghai 200050, China) shanghai institute of ceramics Chinese Academy of Sciences Shanghai 200050 China

β-sialon/nano-size SiC composite ceramic with DyAG(Dy3Al5O12) as grain boundary phase was fabricated through hot-pressing. The effect of nano-size SiC on densification, phase composition, microstructure and mechanica... 详细信息

关键词： Nano SiC Densification and Microstructure of sialon/Nano-size SiC Composites

Tape Casting of Al_2O_3-TiB_2/Al_2O_3-Nano-TiC Multilayer Composites

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Journal of Materials Science & Technology 1997年第4期13卷 324-326页

作者： Yuping ZENG Dongliang JIANG Shouhong TAN and Jingkun GUO(shanghai institute of ceramics, Chinese Academy of Sciences, shanghai 200050, China) shanghai institute of ceramics Chinese Academy of Sciences Shanghai 200050 China

Ceramic tapes, containing Al2O3-25 wt pct TiB2(B) and Al2O3-25 wt pct nano-TiC (c), have been obtained by tape casting process. Numerous tapes (about 60～80 tapes) were prepared by stacking in turn the composition (B) and (C), laminating under 10 MPa pressure, eliminating the solvent and burning out the polymer additives. The final green bodies were hot pressed at 1750℃ and 30 MPa. The composite has a bending strength of 568 MPa and a fracture toughness of 5.8 M Pa·m1/2. SEM analysis exhibits that Al2O3 particle growth was inhibited by TiC particles in C. but TiB2 particles could not hinder Al2O3 growth in B. The curves of GTA indicates that all organic additives could be removed completely above 600℃

关键词： Nano TiB Al Tape Casting of Al2O3-TiB2/Al2O3-Nano-TiC Multilayer Composites TiC

Microstructure and Electromechanical Properties in PMnN-PZT ceramics Sintered at Different Temperatures

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Journal of Materials Science & Technology 2005年第3期21卷 386-390页

作者： Baoshan LI, Zhigang ZHU, Guorong LI and Aili DING State Key Lab of High Performance ceramics and Superfine Microstructure, shanghai institute of ceramics, Chinese Academy of Sciences, shanghai 200050, China Lab. of High Performance ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 China

The microstructure and piezoelectric properties of Pb[(Zr0.52Ti0.48)0.95(Mn1/3Nb2/3)0.05]03 (PMnN-PZT) ceramics have been investigated at different sintering temperatures from 1070℃ to 1280℃. The experimental results suggest that grain sizes and electromechanical properties of the ceramics show strong sintering temperature dependences. Double polarization to electric field (P-E) loops of the PMnN-PZT ceramics are assumed to be the result of the pinning effect of the defect dipoles. The results obtained through X-ray photoelectron spectrum suggest that sintering temperature affects valence of the Mn ion and quantity of oxygen vacancies. Hence, a proper explanation is proposed to illustrate the fluctuation of mechanical quality factor (Qm) due to the sintering temperature.

关键词： Sintering temperature Piezoelectric properties Oxygen vacancies PMnN-PZT