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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Ceramic Society
Journal Basic Information
Journal DOI :
The Korean Ceramic Society
Editor in Chief :
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
Selecting the target year
A Study on the Characteristics of
Thin Films by Sol-Gel Process
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 281~288
to prepare the TiO2 thin films, acetyl-acetone(2.4-pentanedione)(1 : 1 molar ratio) was dissolved in the propanol solution of titanium(IV)isopropoxide(Ti[OCH(CH3)2]4). Al, Cr and Sb in the form of soluble salt and niobium ethoxide were added s dopants, respectively. Thin films were coated by the dip-coating method and characteristics were investigated by XRD, SEM and conductance meter. As a result, viscosity of sol was maintained below 4 centi Poise more than 20 days, and crystal growth and diminution of resistivity occurred as the heat treatment temperature increased. The grains grew over 1
and the lowest resistivity was obtained when Nb was added at 130
A Study on the Electric-magnetic Properties of Mg-ferrite with Various Mixing Time of Raw Materials
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 289~294
As the results of the study on the effects of mixing time for raw materials to the electric and magnetic properties of Mg-ferrite, the fraction of spinel phase after calcination and the geometry density of sintered Mg-ferrite increased from 30% to 100% and from 2.5g/cc to 4.25g/cc respectively due to mixing-homobenity of raw materials. The AC resistivity of grains decreased and lattice parameter, saturation magnetization increased due to the increase in Fe+2 of sintered body. conclusively the characteristic of powder after calcination had strong influence on the microstructure, electric, and magnetic properties in Mg-ferrite sintered body.
Stabilization of the Perovskite Phase and Dielectric Properties in the System
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 295~304
Stabilization of the perovskite phase and sequence of reactions occuring during calcination were studied with solid solutions formed between Pb(Zn1/3Nb2/3)O3 and Pb(Fe1/2Nb1/2)O3. In the PZN-PFN composition of equal molar ratio, rhombohedral type pyrochlore phase (Pb2Nb2O7) and PbO-rich distorted cubic type pyrochlore phase (Pb3Nb2O8) were coexisted as intermediate phases at temperatures below 85
, and these phases transformed to a stable cubic type pyrochlore phase, Pb3Nb4O13 solid solution and a perovskite solid solution at temperatures above 85
. The major stable phase as increasing sintering temperatures was a perovskite phase in this binary system and prominent suppression of the pyrochlore phase was achieved by substituting Zn2+ with Fe3+ or by increasing sintering temperature. The composition containing 20mol% PZN possessed the best dielectric properties, and the dissipation factor was lower than 5% in all compositions.
Effects of Physico-chemical Factors of Sol on the Degree of Preferred Orientation in
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 305~312
Thin films of Pb(Mg, Zn)1/3Nb2/3O3 were fabricated by spin coating the Pb-Mg-Zn-Nb-O complex alkoxide sols on(111) Pt-coated MgO (100) planes. It was observed that the content of H2O and the rheological characteristics of sol greatly influenced the orientation of perovskite grains after thin-film formation. A strong preferential orientation of (100)-type planes of the perovskite grains was obtained for the sol aged for 15 days with the molar ratio of H2O to total metal alkoxides=2. As small angle X-ray scattering experiment in the Porod region was performed to correlate the observed preferential orientation with the network structure of precursors at various stage of aging. It was shown that the degree of branching of the Pb-Mg-Zn-Nb-O precursor chain had a direct effect on the preferred oreintation, and weakly branched precursor systems led to highly oriented grains after thin-film formation.
Magnetic and Electrical Properties of Mn-Zn Ferrite Thin Films Deposited by Ion Beam Sputtering
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 313~320
We investigated the preferred orientation, electrical and magnetic properties of the Mn-Zn ferrite thin films deposited on SiO2/Si(100) by ion beam sputtering. The Cu-added Mn-Zn ferrite thin films had a preferred orientation of (111) with a weak orientation, (311). While the Zn-added one had a strong (111) preferred orientation. The saturation magnetization of the Cu- or Zn-doped Mn-Zn ferrite films increased with increasing substrate temperature (Ts) due to the increase of grain size and the enhancement of crystallinity. For the same reason the coercivity of Cu- or Zn-doped Mn-Zn ferrite films deposited at low Ts increased with increasing Ts, but those of the films deposited at high Ts slightly decreased not only because the defect density of the films decreases but because more grains have multi-domains with increasing Ts. The resistivity of Cu- or Zn-added Mn-Zn ferrite thin fims measured by complex impedance method decreased with increasing Ts due to the ehhancement of crystallinity as well as due to the increase of grain size.
Optical Transparency and Microstructure of
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 321~330
Homogeneous and monolithic TiO2-SiO2 binary aerogels were prepared by supercritical drying. Optical transparency was increased with adding acid catalyst during two step hydrolysis and with decreasing water content. These differences in optical transparency were related to microstructures of gel network formed through polycondensation reaction during supercritical drying process, rather than the final composition of aerogel.
The Oxidation and Sintering of
Powder Mixture by using Microwave (Hybrid) Heating
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 331~340
Microwave (Hybrid) Heating (MHH) was used to oxidize and sinter Al-Al2O3 powder mixture. For 25 v/o Al specimen and 35 v/o Al specimen, the total processing to produce low-shrinkage reaction bonded alumina was carried out within 1 hour even though conventional furnace process took more than 10 hours. Compared with conventional fast firing process, MHH process increased more than 40% oxidation at the same temperature, and these high oxidation rates were thought to be caused by the surface ohmic current on Al particles.
Temperature Profile Analysis of
in Self-Propagating High Temperature Synthesis
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 341~348
An analysis of the use of temperature profiles in the determination of the kinetic parameters of combustion synthesis of Ti5Si3 were investigated. From profile analysis, an apparent activation energy of 12KJ/mol was calculated. The Maximum heating rate achieved during 10wt% Ti5Si3 reaction by the product dilution method was approximately
104 K/s. Coupling this value with the measured wave velocity of 7.02 cm/s yields a maximum thermal gradient of 2.14
103 K/cm. The value of tr (=t*) was calculated to be 1.2
10-1 s and the value of td (=tx) was calculated to be 32.89 s. Using the definition of t* and the measured wave velocity, the effective thermal diffusivity,
, was calculated to be 0.59
/s. From these analysis, the power function, G, was also calculated.
Synthesis and Characterization of Alumina Composite Membrane by Al Evaporation and Thermal Oxidation
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 349~358
The ceramic composite membrane was synthesized by thermal oxidation after evaporation of Al on the support prepared by slip casting process. Oxidation was performed at
under dry oxygen atmosphere. It was considered as optimum oxidation condition that the membrane showed a knudsen behaviro. A further oxidation resulted in an increase of gas permeability because top layer became densified. Then, a multi-layered composite membrane was synthesized through a sol-gel method, evaporation and thermal oxidation of Al coating processes. While the membrane was thermally stable up to 80
, gas permeability was rapidly decreased even at a slight amount of deposition of Al.
The Effect of Microstructure on the Ionic Conductivity in the
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 359~365
The grain boundary effect on the ionic conductivity was investigated using a.c. admittance analysis in (Bi2O3)0.715(CaO)0.285 oxygen-ion conducting solid electrolyte. As a separated arc representing grain boundary polarization was not observed in the admittance plane, bulk conductivity was measrued for samples with various grain sizes in the temperature range from 48
and the conductivity distribution between grain interior and grain boundary was determined by the reported analytical methods. In the above temperature range, grain boundary worked as a high conductive path instead of blocking layer and ionic conduction through grain boundary was significant. The activation energy for conduction through grain and grain boundary was 78 and 106 kJ/mol, respectively.
Tile Size Dependency of Ballistic Performance in Alumina
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 366~370
The ballistic efficiency of alumina tiles with various sizes, shapes, and target configurations was measured by the thick backing plate technique. The ballistic efficiency of square tiles roughly 8 mm thick struck by 12.7mm diameter bullets rapidly increased with tile size up to about 100mm, then tended to saturate. Circular shape tiles had lower ballistic efficiencies than those of square shape tiles for the same width and thickness. Small tiles (50mm) that were recessed in aluminum wells had a significantly higher ballistic efficiency than tiles placed on a flat surface. However, the difference in the ballistic efficiency between the two target configurtions became small at larger tile sizes. All the results could be explained by the effect of reflected waves at edges and the propagation of resulting cracks on the penetration process.
Growth and Electrical Characteristics of Ultrathin
Film Formed in an Electron Cyclotron Resonance Oxygen Plasma
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 371~377
Silicon oxide films were grown on single-crystal silicon substrates at low temperatures (25~205
) in a low pressure electron cyclotron resonance (ECR) oxygen plasma. The growth rate of the silicon oxide film increased as the temperature increased or the pressure decreased. Also, the thickness of the silicon oxide film increased at negative bias voltage, but not changed at positive bias voltage. The growth law of the silicon oxide film was approximated to the parabolic form. Capacitance-voltage (C-V) and current density-electric field (J-E) characteristics were studied using Al/SiO2/p-Si MOS structures. For a 10.2 nm thick silicon oxide film, the leakage current density at the electric field of 1 MVcm-1 was less than 1.0
10-8Acm-2 and the breakdown field was higher than 10 MVcm-1. The flat band voltage of Al/SiO2/p-Si MOS capacitor was varied in the range of -2~-3 V and the effective dielectric constant was 3.85. These results indicate that high quality oxide films with properties that are similar to those of thermal oxide film can be fastly grown at low temperature using the ECR oxygen plasma.
on the Dielectric and Piezoelectric Properties of
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 378~384
on the dielectric and piezoelectric properties of
system were investigated. The addition of La2O3 to the system enhanced electromechanical coupling factor (kp), piezoelectric constant (d33), but hardly changed mechanical quality factor (Qm). On the other hand, the addition of
increased Qm significantly, but did not degrade kp and d33 so much. The piezoelectric properties of
were very good and kp, d33, Qm were 55%, 350
10-12C/N, 780, respectively. The size of the grains was proportional to the change of c/a (tetragonality) ratio caused by the addition of
, and dielectric, piezoelectric properties were sensitive to the amountof pyrochrole phase.
Preparation and Characterization of Porous Glass in
System ; Addition Effects of
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 385~393
Akali-resistant porous glass was prepared by phase separation in Na2O-B2O3-SiO2 system containing ZrO2 and MgO. ZrO2 was added for alkali-resistance and MgO for anti-cracking during leaching. Optimal content of ZrO2 for alkali-resistance was 7wt% and devitrification by heat treatment resulted from further addition. Pore size and pore volume were decreased and specific surface area was increased with ZrO2 addition due to depression in phase separation. Addition of 3mol% MgO to mother glass containing 7wt% ZrO2 was effective for anti-crack during leaching. In this case, with phase separation at 55
for 20 hrs. crack-free porous glasses could be prepared. The relation between pore size r and heat treatment time t at 55
was D=25.58＋18.16t. According to measurement of gas permeability, the mechanism of gas permeation was Knudsen flow. N2 and He permeability of porous glass which was prepared by heat treatment at 55
for 20 hrs. were 0.843
.s.Pa and 2.161
Phase Equilibria of the Ferrous Ferrite System of
Journal of the Korean Ceramic Society, volume 32, issue 3, 1995, Pages 394~402
Electrical conductivity and thermoelectric power of the ferrous ferrite system of (Mg0.29-yMnyFe0.71)3-
O4 have been measured as function of the thermodynamic variables, cationic composition(y), temperature(T) and oxygen partial pressure(Po2) under thermodynamic equilibrium conditions at elevated temperatures. On the basis of the electrical properties-phase stability correlation, the stability regions of the ferrite spinel and its neighboring phases have been subsequently located in the log Po2 vs. y and log Po2 vs. 1/T planes in the ranges of 0 y 0.29, 1100 T/
1400 and 10-14 Po2/atm 1. The stability region, Δlog Po2(y, 1/T), of the ferrite spinel single phase widens with increasing Mn-content(y) and the boundaries of each region are linear against 1/T with negative slopes.