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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Crystal Growth and Crystal Technology
Journal Basic Information
Journal DOI :
The Korea Association of Crystal Growth
Editor in Chief :
Volume & Issues
Volume 8, Issue 4 - Aug 1998
Volume 8, Issue 3 - Jun 1998
Volume 8, Issue 2 - Apr 1998
Volume 8, Issue 1 - Feb 1998
Selecting the target year
Sapphire single crystal growth by the modified heat exchanger method : I. Preparation with the square cross-section
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 1~9
In this study, we have investigated the preparation conditions of 45
20(mm) square cross-section sapphire single crystal by the modified heat exchanger method using water as a coolant. Melting and solidification processes were optimized by the systematic change of the chamber pressure with the heater temperature. As a results, solidification temperature was between 1960 and
. The crucible was formed by handling. Therefore its shape should had the 'spiral type' ear at edge of its side. Heat exchanger affected to the temperature distribution and gradient of molten alumina. Heat flux and unmelted seed were controlled by volume of heat exchanger. Voids were controlled by the cooling rate of the heater below
On the photorefractive resistance characteristics of lithium niobate single crystals with doping
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 10~17
The characteristics of the lithium niobate single (
) crystals grown doped with
ions, which are well-known as the ions improving the photorefractive resistance of
, have been analysed in comparision with those of undoped
crystal. In particular,
doping was estimated to increase the photorefractive resistance indirectly from the optical and electrical properties. Therefore, the
crystals doped with ZnO could be used for high intensive laser device application.
Czochralski crystal growth by the accelerated crystal rotation technique
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 18~28
A laboratory experiment was made of a control of temperature oscillation in Czochralski convection. Numerical computation was also made to delineate the control of temperature oscillation. The suppression of temperature oscillation was achieved by varying the rotation rate of crystal rod (
), where A denotes the amplitude of rotation rate and f the frequency factor. Based on the inherent dimesionless time period of temperature oscillation (
), the suppression rate of temperature oscillation was characterized by the mixed convection parameter (
). The optimal values of A and f were also scrutinized. To understand the suppression mechanism of temperature oscillation, the controls of isotherm(
) and equi-vorticity(
) were investigated.
Defects control in SiC single crystals
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 29~35
Substrates, SiC raw materials and graphite crucibles were purified for growing the high quality 6H-SiC single crystal ingot. Especially, XRD data of raw materials were analyzed before and after purification. We have grown 6H-SiC single crystal ingot up to 33 mm in diameter and 11 mm in length and SiC wafer for using the substrate and observing the internal defects was about 33 mm in diameter and 0.5 mm in thickness. Utilizing optical microscpe and Raman spectroscopy, internal defects density and crystallinity of the SiC wafer obtained by purification processes before crystal growth were measured. As a result, micropipe density and planar defect density were 100/
respectively. Therefore, high quality 6H-SiC single crystal could be grown because internal defects density of 6H-SiC single crystal ingot was decreased by the purification processes before crystal growth.
The structure and synthesis of intercalation compound between a layered double hydroxide and an organic compound
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 36~41
Intercalation compounds of alkyl sulfonates into layered double hydroxides (LDH) have been directly synthesized. From the X-ray diffraction data and the alkyl sulfonates size, the orientation of the intercalated alkyl sulfonate into the layered double hydroxide was determined. The intercalated alkyl sulfonate is arranged with molecular chain perpendicular to the hydroxide layer with an antiparallel pattern.
Hydrothermal synthesis of PLT[
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 42~48
Synthesis of PLT(
, x=0.1~0.3) powders was carried out by hydrothermal method. Optimal conditions for synthesis were
of reaction temperature, 8M-KOH solution of hydrothermal solvent and 12 hrs reaction time, and the monolithic
particles were obtained with the composition of x
0.2. The tetragonality(c/a) and the phase transition temperature were decreased by the increment of the
contents in PLT solid solutions, and the Curie temperature of the
. The shape of the synthesized particles were nearly spherical and the size was in the 20~200 nm range.
Hydrothermal synthesis of
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 49~54
fine particles were synthesized by hydrothermal method.
were used as staring materials, and it was possible to synthesize
fine particles in pure water by using excess
. The shape of synthesized particles are irregular but near spherical, and the particle size depends on the temperature and Ba/Ti atomic ratio.
Preparation of A and Y type zeolite film by hydrothermal crystallization
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 55~63
A and Y type zeolitic crystal films were synthesized on porous supports from the reaction mixture of 1.9
composition, respectively. The zeolite film was characterized by XRD and SEM. The crystals grown on the porous matrix were very closely bound together and the thickness of membrane was about 8-15
. The densely intergrown crystals could be also synthesized by the hydrothermal treatment at
after pressing the reaction mixture without addition of water. A zeolite membrane crystallized as a thin film showed the selective permeability of water from water and methanol mixture through the molecular sieving activity of micropores.
A study on the Poly-
thin film deposition(II) Variation of surface roughness, grain size and electrical property with deposition parameters
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 64~72
In this work, we have investigated the change of surface roughness, grain size and crystallinity of Poly-
films deposited with the variation of deposition parameters (temperature, pressure, Ge composition ) and the effect of these results on the electrical resistivity. The crystallinity and the grain size were increased with increasing deposition temperature and Ge composition. Also, the electrical resistivity was decreased by enhanced grain size, while the surface roughness was increased. With increasing deposition pressure, the crystallinity was increased, but the grain size and the cluster size were decreased, by which the surface roughness was decreased. And the electrical resistivity was increased. Based on the effect of the crystallinity and the grain size on the electrical resistivity, it was founded that the electrical resistivity was depend on the grain size rather than the crystallinity.
A study on the magnetic properties and microstructure of spin-valve type multilayer for giant magnetoresistance
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 73~82
The exchange anisotropy is the unidirectional magnetic anisotropy which comes from exchange interaction between antiferromagnetic layer and ferromagnetic layer. The application of this phenomenon to MR read head and spin-valve type GMR (Giant Magnetoresistance) head has been studied extensively. In our study, we intended to apply exchange anisotropy of NiO/NiFe bilayer to spin-valve type GMR element. Above all, we studied the exchange anisotropy of NiO/NiFe bilayer, and focused especially on the effect of NiO deposition condition. And we found that Ar pressure during NiO deposition was crucial factor for the exchange anisotropy of NiO/NiFe bilayer. The lower the Ar pressure is, the better the characteristics of exhange anisotropy is. Then, we applied this optimum condition of NiO/NiFe bilayer to spin-valve type GMR element. Finally we got spin-valve type GMR element which had 3.6 % MR ratio, 16 Oe switching field, and 0.25 %/Oe sensitivity.
Stage transformation characteristice of Li, K and Na-graphite intercalation compounds
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 83~90
Stage transformation characteristics of Li, K and Na-graphite deintercalation compounds (GDICs) were studied under consideration of a deintercalation mechanism of the intercalants between carbon layers. Li-graphite intercalation compounds (GICs) synthesized by a controlling temperatures and pressures have been spontaneously decomposed in the atmosphere. By X-ray differaction analysis the
-values of stage 1 and 2 were identified to be 3.71 and 7.06
, respectively. After 6 weeks, the deintercalation reaction of the Li-GICs ceased and only residual compounds could be observed. K-GICs were synthesized by the modified two-bulb method resulting in structural stabilities and stage transitions. By X-ray diffraction analysis the very stable K-graphite residue compounds were observed after 10 weeks. Na-GICs with stage 1 and 2 were synthesized using the high temperature and pressure technique. The temperature dependence of a deintercalation reaction and a thermal stability of Na-GICs were discussed. The structure changes of the Na-GDICs depending on heating rates were identified by X-ray diffraction. According to the deintercalation process, the stage transformations could be attributed to irregular deintercalations of the GDICs with disordered stage.
An empirical formula for the calculation of lattice parameters of the huntite-borate crystals
Kiyoshi Shimamura ; Valery l. Chani ; ; Tsuguo Fukuda ;
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 91~96
An empirical relationship which can be calculated to the lattice constants
for the borate crystals with huntite structure were determined. Different compositions of twenty-eight were used for the calculations. These empirical formulas can be used to predict lattice parameters of unknown compositions as a function of the average ionic radii in the trigonal and octahedral sites of the huntite structure.
Antioxidation mechanism of Al metal powders on
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 97~105
Antioxidation mechanism of Al metal powders on
refractory was investigated in temperature range from 800 to
. The addition of 5 wt% Al metal powders suppressed the oxidation of carbon in
-C sample. The carbons were distributed uniformly on the surface and the interface of the
-C-Al. Reaction products of
and AIN were found with a composition of Al-C at temperatures between 800 and
and transformed to
. Cavity structures related to the to the formation of
were observed for the AI-C after heating at
ofr 1 hour. Thermodynamic mechanism was considered to discuss the formation
, AlN and their transformation to
, which leads to the effect of oxidation resistance.
Henry성s law behavior on multilayer adsorption considered layer location dependence of the bonding energy
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 106~110
The effect of microstructure of electrical discharge machinable silicon nitride on wear resistance
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 111~116
Silicon nitride is hard and tough ceramic material. Hereby, mechanical machinability is very poor. It has also high electrical resistance. Silicon nitride of extremely high electrical resistivity becomes conductive ceramic composite by adding 30 wt% TiN. Ceramics with high electrical conductivity can be electrical discharge machined. Using by the Electrical Discharge Machining (EDM) technique.
ceramic composite with high electrical conductivity is utilized to make metal working tool. These tool materials have severe wear problem as well as oxidation. Post HIP processing after sintering
ceramic composites was performed. The tribological property of
composite as a function of content of TiN was investigated in air, at room temperature. The hardness, fracture toughness, and flexural strength were compared with the wear volume. SEM observation of wear tracks can make an explanation of wear mode of
Evaluation of mechanical backside damage by minority carrier recombination lifetime and photo-acoustic displacement method in silicon wafer
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 117~123
We investigated the effect of mechanical backside damage in Czochralski grown silicon wafer. The intensity of mechanical damage was evaluated by minority carrier recombination lifetime by laser excitation/microwave reflection photoconductivity decay method, photo-acoustic displacement method, X-ray section topography, and wet oxidation/preferential etching methods. The data indicate that the higher the mechanical damage intensity, the lower the minority carrier lifetime, and the photo-acoustic displacement values increased proportionally, and it was at Grade 1: Grade 2:Grade 3 = 1:19.6:41 that the normalized relative quantization ratio of excess photo-acoustic displacement in damaged wafer was calculated, which are normalized to the excess PAD from sample Grade 1.
Raman scattering in porous silicon
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 124~130
The Raman scattering was studied from the porous silicons which were made by changing anodization current. As the current density was increased, it was observed that Raman was gradually far from the value of 520.5
and the full width half maximum increased. The decrease of radius of cylindrical porous crystal was calculated and the increase of its length was investigated through AFM.
Composite copper powder from Kelex 100
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 131~137
A composite copper coated powder was generated by pressure hydrogen stripping copper from Kelex 100 solvent extractant in the presence of silica powder. Within the limitation of solvent extraction under constant conditions, both loading level and stripping rate were reproducible. The stripping copper kinetics are reduced from a divalent state to a metallic state and then deposited on the surface of the silica powder. Copper nucleates heterogeneously on the seed particles. They are giving an agglomerated and non - uniform powder.
Preparation of <
fone powders using iron(III) nitrate
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 138~144
fine powders with the sizes smaller than 0.5
were prepared by the solvolysis and condensation reaction using iron(III) nitrate and ethanol as starting materials. The variation of pH and the change of FT-IR absorption peak were observed to study the reaction mechanism of iron(III) nitrate solution. In addition, the decomposition mechanism of the precipitated gel was investigated by differential scanning calorimeter, X-ray diffractometer and FT-IR spectrometer. Scanning electron microscope and BET method were performed to analyze the effects of Iron (III) nitrate concentration and reaction temperature on the particle size of
The effect of
on mechanical strength and microstructure of TZ-8YS solid oxide fuel cell electrolyte
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 145~150
The electrical and mechanical properties of the 8 mol% yittria-stabilized zirconia and alumina composites have been examined as a function of the alumina content. The 3-point bending strength and fracture toughness of the composites increased with increasing alumina content up to 20 wt%. The average grain size of the composites decreased with increasing alumina content up to 20 wt%. The composite with 5 wt%
showed a 3-point bending strength of 310 MPa and fracture toughness about
. The electrical conductivity of the composites at
increased slightly with increasing alumina content up to 10 wt% and decreased monotonically with alumina content. The conductivity of the TZ-8YS with 5 wt% alumina was 0.4 S/cm at
Development of PTCR compositions for automobile
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 151~159
Elelctrical properties of
were characterized with addition of
and Mn to develope the composition of PTC thermistor suitable as a current limiting device for automobile motor system. With the addition of 0.2 mol%
, the minimum resistance of 16.5
cm was obtained at room temperature.
exibited a minimum resistance of 50
cm with addition of 1.6 mol%
. The grain size of
decreased from 34.95
m to 13.4
m and thus breakdown voltage could be improved by changing the composition as
with substition of 5 mol% Ca into Basites. When 0.04 mol% Mn was added, the optimum PTCR properties could be obtained : the resistivity at room temperature and
Substitutions of coloring ions and their effects on wagnerite pigments for cetamic glazes
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 160~168
In order to investigate the color variation and the solubility limit in wagnerites by metal ion substitution, wagnerite (
) was synthesized and then, substituted by coloring metal ions, especially
ions. When calcium was replaced with Mg, Co, Ni and Cu divalent ions, solid solutions were formed with a limited solubility. Single phase wagnerites were synthesized by the substitution of Ca with Mg and Co, and their colors were white and purple, respectively. Substitutions with
were succeeded in the specific composition and the substitution of vanadium for
were attempted, resulting in the wagnerites of dark purple, dark gold and light yellow colors. The substitution of chlorine was, also, attmepted for the fluorine site.
Preparation of bioactive materials by crystallization sintering
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 169~178
The crystal phases precipitated in various compositions glass of CaO-
system, were identified by XRD. E composition (CaO 49.4,
8.8 wt%) glass in which both apatite((
) crystals would precipitate by heating, was selected as an experimental composition to prepare the glass ceramics with high bending strength and good bioactivity to the living bone. Glass powders of E composition were unidirectionally crystallized at
C in the temperature-gadient furnace and the resultant glass ceramics were characterized. Bending strength of the glass ceramics was also measured. To investigate the bond forming ability between the glass ceramics and living bone tissue, soaking test of glass ceramics in simulated body fluid was carried out. Densed glass ceramics composed of apatite and
-wollastonite crystal were prepared by unidirectional crystallization under the optimum conditions. (2 0 2) plane of
-wollastonite crystals tended to grow perpendicularly to the crystallization direction. Average bending strength of this glass ceramics was 186.9 MPa, higher than that of the glass ceramics prepared by isothermal (not directional) crystallization In soaking test, a thin layer of apatite crystallite was formed on surface of the glass ceramics in 3 days. Apatite crystals formed on the glass ceramics could be act a role to make the chemical bond between the glass ceramics and living bone tissue.
A study on the flaking phenomenon by the reaction between glass and solution
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 179~186
We have been investigated the effects of the initial pH of the aquous solution, reaction temperature and time for the flaking of the soda-lime glass container. Flaking of glass occuurred in the cases of the
, above pH 11 of solution with no
ions in solution. The pH of the solution approached to pH 10 under the conditions of below pH 9 of start solution. The flaking mechanism of the glass seem to be composed of formation of leached layer of
ion and separation of these layers during the cooling by the difference of thermal expansion between leached layer and glass surface. The leaching of alkali ions in glass depends on the pH condition of the start solution and the temperature. In the case of
ions are added,
ions accelerate the flaking of the sodalime glasses and forms the magnesium silicate compound which result in the decrease of the pH of the solution.
The analysis of columnar to equiaxed dendritic transition during alloy solidification
Journal of the Korean Crystal Growth and Crystal Technology, volume 8, issue 1, 1998, Pages 187~192
Generally the solidified microstructures of materials consist of the columnar and equiaxed dendritic regions, and many theoretical studies about columnar-to-equiaxed transition have been done because that is closely related to the mechanical and physical properties of products. In this study, the modified equation based on the Hunt's analytical columnar-to-equiaxed transition condition which was derived from heterogeneous nucleation and grain growth in front of the columnar dendrite tip under directional solidification, was obtained applying the growth-velocity-dependent distribution coefficient and liquidus slope to Hunt's. The effects of the number of nucleation sites, nucleation temperature, alloy composition, growth velocity and liquid temperature gradient on the transition for Al-Cu alloys have been investigated.