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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Ceramic Society
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Journal DOI :
The Korean Ceramic Society
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Volume & Issues
Volume 32, Issue 12 - Dec 1995
Volume 32, Issue 11 - Nov 1995
Volume 32, Issue 10 - Oct 1995
Volume 32, Issue 9 - Sep 1995
Volume 32, Issue 8 - Aug 1995
Volume 32, Issue 7 - Jul 1995
Volume 32, Issue 6 - Jun 1995
Volume 32, Issue 5 - May 1995
Volume 32, Issue 4 - Apr 1995
Volume 32, Issue 3 - Mar 1995
Volume 32, Issue 2 - Feb 1995
Volume 32, Issue 1 - Jan 1995
Volume 1, Issue 4 - 00 1995
Volume 1, Issue 3 - 00 1995
Volume 1, Issue 2 - 00 1995
Volume 1, Issue 1 - 00 1995
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Synthesis and Characterization of Submicrometer Monodispersed Ceramic Powders of Aluminium Titanate-Mullite Composite by Sol-Gel Process
Ik Jin Kim ; Do Kyung Kim ; Hyung Bock Lee ; Young Shin Ko ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 1~1
Submicrometer, monosized ceramic powder of Al₂
, mullite and aluminium titanate mullite composition was prepared by stepwise alkoxide hydrolysis of tetraethylorthosilicate and titaniumtetraethoxide in Al₂O₃ ethanolic solutions. All particles produced by sol-gel-process were amprphous, monodispersed and with a narrow particle-size distribution. Compacts fired above 1300℃ formed aluminium titanate. Mullite formed first at 1480℃. After decomposition test at 1100℃, and cyclic thermal decomposition test at 750-1400-750℃ for 100hrs., aluminium titanate was well stablized by composition with mullite.
Quantitative Analysis of Ultrathin SiO₂ Interfacial Layer by AES Depth Profilitng
소주원 ; 김종석 ; 이원종 ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 7~7
When a Ta₂
dielectric film is deposited on a bare silicon, the growth of SiO₂ at the Ta₂TEX>$O_5$/Si interface cannot be avoided. Even though the SiO₂ layer is ultrathin (a few nm), it has great effects on the electrical properties of the capacitor. The concentration depth profiles of the ultrathin interfacial SiO₂ and SiO₂/Si₃N₄ layers were obtained using an Auger electron spectroscopy (AES) equipped with a cylindrical mirror analyzer (CMA). These AES depth profiles were quantitatively analyzed by comparing with the theoretical depth profiles which were obtained by considering the inelastic mean free path of Auger electrons and the angular acceptance function of CMA. The direct measurement of the interfacial layer thicknesses by using a high resolution cross-sectional TEM confirmed the accuracy of the AES depth analysis. The SiO₂/Si₃N₄ double layers, which were not distinguishable from each other under the TEM observation, could be effectively analyzed by the AES depth profiling technique.
Effects of Thermal Annealing on Dielectric and Piezoelectric Properties of Pb(Zn, Mg)₁/₃Nb₂/₃O₃-PbTiO₃ System in the Vicinity of Morphotropic Phase Boundary
Hyun M. Jang ; 이규만 ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 13~13
Effects of thermal annealing on the dielectric/piezoelectric properties of Pb(Zn, Mg)₁/₃Nb₂/₃O₃PbTiO₃ ceramics (PZMNPT) with Zn/Mg=6/4) were examined across the rhombohedral/tetragonal morphotropic phase boundary (MPB). Both the relative dielectric permittivity (εr)and the piezoelectric constant(
)/electromechanical coupling constant (kp)were increased by thermal annealing (800°∼900℃) after sintering at 1150℃ for 1 hr. Based on the dielectric analysis using the series mixing model and the concept of a random distribution of the local Curie points, the observed improvements in the dielectric and piezoelectric properties of PZMN-PT were interpreted in terms of the elimination of PbO-rich amorphous intergranular layers(∼1nm) induced by thermal annealing. A concrete evidence of the presence of amorphous grain-boundary layers in the unannealed (as-sintered) specimen was obtained by examining the structure of intergranular region using a TEM.
Electrical Conductivity of a TiO₂ Thin Film Deposited on Al₂O₃Substrates by CVD
황철성 ; 김형준 ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 21~21
Electrical conductivity of TiO₂ thin films, deposited on Al₂O₄ substrates by metal organic chemical vapor deposition (MOCVD), was measured by four-point probe method in a temperature range from 800℃ to 1025℃ and an oxygen partial pressure range from 2.7×
atm to 1 atm. In the low oxygen partial pressure region n-type conduction was dominant, but in the high oxygen partial pressure region p-type conduction behavior appeared due to substitution of Ti ions by Al ions, which were diffused from the substrate during post deposition annealing process. Electrical conductivity of the film decreases in the n-type region and increases in the p-type region as the oxygen partial pressure increases. The transition points, which show the minimum conductivity, shifted to the higher oxygen partial pressure region as the measuring temperature increased, but it shifted to lower oxygen partial pressure region with an increase in the post annealing temperature. The results were also discussed with the possible defect models.
Corrosion of Alumina-Chromia Refractory by Alkali Vapors: 1. Thermodynamic Approach
이경호 ; Jesse J. Brown Jr ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 29~29
Theoretical predictions were made for thermodynamically stable phases which formed when alkali(sodium and Potassium) vapors reacted with the 90% All₂O3-10% Crl₂O₃refractory under coal gasifying atmosphere using the computer program of SOLGASMIX-PV. The calculation results showed that the stable compounds that formed were Xl₂O·All₂O₃ and Xl₂O·11All₂O₃(X=
), depending upon the alkali concentration. The presence of sulfur in gasifying atmospheres did not appear to affect the species of alkali reaction products. Alkali attack at high temperatures is likely to cause serious degradation at the hot face of the refractory, indicating that the alkali concentration is an important factor to affect the degradation of the refroctory.
Characterization of Spray-Dried Yttrium Aluminum Garnet Powder
S.M. Sim ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 35~35
Yttrium aluminum garnet(YAG) powders were synthesized by spray-drying of the hydroxides coprecipitated from a mixture of aqueous solutions of Al(NO₃)₃·9H₂O and Y(NO₃)₃·6H₂O Phase formation in the powders during heat treatments and their sintering charactristics were investigated. In the powder obtained by washing the hydroxides before spray-drying, a metastable yttrium aluminum hexagonal (YAH) phase was first crystallized and then transformed into YAG as temperature was increased. The formation of YAH was attributed to a deviation in compositions of the particles from the starting composition of YAG. However, the powder prepared without washing step contained a stable yttrium aluminum monoclinic(YAM) phase in addition to YAG due to a large deviation from the starting composition. A powder compact of a single phase YAG was pressureless-sintered for 4 hrs at 1700℃ and the density was 93% of the theoretical density.
Thermal Deintercalation of Ethylammonium-Aluminosilicate Intercalates with Various Layer Charges
Jin Ho Choy ; 최영준 ; 한양수 ; 김배환 ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 40~40
Ethylammonium-layered aluminosilicates intercalates were prepared by ion exchange reaction between the layered silicates with different layer changes density of 0.32∼0.41 e per unit formula and ethylammonium chloride. A kinetic study on the thermal deintercalation of the ethylammonium-layered silicate intercalates was carried out by range of 350℃ to 480℃ (heating rate of 10℃/min). Based on the Ozawa's method, the activation energies of the thermal deintercalation reaction were estimated as 171.2∼133.0 kJ/mol, which increase linearly with the layer charge densities.
Hot Pressing of the Silicon Nitride Based Ceramics and Their Mechanical Behavior
D. S. Park ; Lee, H. D. ; W. S. Choi ; D. S. Lim ; B. D. Han ;
Journal of the Korean Ceramic Society, volume 1, issue 1, 1995, Pages 45~45
Four kinds of silicon nitride based ceramic materials have been hot pressed. Effect of the sintering additives on the phase transformation, microstructural development and mechanical properties was investigated. While sintering under the same condition a big difference among the microstructures of the specimens, they appeared alike if sintered to have a similiar α-β phase ratio. The specimen of the stoichiometric α-β sialon composition showed very limited amount of the intergranular glassy phase and a significant degree of the residual stress. It exhibited almost no strength degradation up to 1300℃, and the strength of the specimen degraded more as its composition deviated from the stoichiometry.