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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Korean Journal of Materials Research
Journal Basic Information
Journal DOI :
The Materials Research Society of Korea
Editor in Chief :
Volume & Issues
Volume 5, Issue 8 - Dec 1995
Volume 5, Issue 7 - Oct 1995
Volume 5, Issue 6 - Sep 1995
Volume 5, Issue 5 - Aug 1995
Volume 5, Issue 4 - Jun 1995
Volume 5, Issue 3 - May 1995
Volume 5, Issue 2 - Apr 1995
Volume 5, Issue 1 - Feb 1995
Selecting the target year
Dielectric properties of low temperature firing glass reacted (Ba, Sr)
$ ceramic capacitors
Gu, Ja-Won ; Seol, Yong-Geon ; Choe, Seung-Cheol ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 151~156
Low temperature firing
dielectrics were successfully prepared with lead based glass and those electrical properties were investigated. Different amount of PbO content glass materials were added to dielectrics to investigate the sinterability and its dielectric properties. Also, various compositions of ceramic capacitors were prepared to applicate in multilayer ceramic capacitors. A large amount of experiment has been done with various Pb contented glasses and different sintering temperatures. The sintering temperature of
can be reduced from
to as low as
with 4wt% addition of
glass materials. Its dielectric constant at room temperature was up to 8100 with low dielectric loss, 0.005. This ceramic capacitor showed fully fired microstructures with its grain size of 1-3
. The sintered body which was sintered at
for 2hr with 4wt%
glass material addition satisfied the Z5U specification of the EIAS.
Effects of Mo additions on the room-temperature deformation behavior of polysynthetically twinned (PST) crystals of TiAl
O, Myeong-Hun ; Kim, Min-Cheol ; Wi, Dang-Mun ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 157~168
The effects of Mo additions on the microstructure and the room temperature deformation behavior of polysynthetically twinned (PST) crystals of TiAl were studied in order to get a basic conception for alloying additions on the two-phase TiAl compounds with the lamellar structure. It was found that the Mo additions in TiAl PST crystals increase both the yield stress and tensile elongation to fracture but the increase in yield stress deppend on the angle
at which the lamellar boundaries lie from the loading axis. The large difference in yield stress between specimens deformed parallel(
) to the loading axis and those deformed in intermediate orientations could be plained by the difference in Mo content between the TiAl and the
phases. It was also found that the Mo-doped specimens with intermediate orientation fail by cracking zigzag across to the lamellar boundaris, which is the same fracture mode as that of binary specimens with intermediate orientations tested in vacuum This suggests that Mo atoms are thought to play a role to reduce the environmental embrittlement of binary PST crystals, resulting in increasing the tensile ductility.
Effect of Stuffing of TiN on the Diffusion Barrier Property (II) : Cu/TiN/Si Structure
Park, Gi-Cheol ; Kim, Gi-Beom ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 169~177
The diffusion barrier property of 100-nm-thick titanium nitride (TiN) film between Cu and Si was investigated using sheet resistance measurements, etch-pit observation, x-ray diffractometry, Auger electron spectroscopy, and transmission electron microscopy. The TiN barrier fails due to the formation of crystalline defects (dislocations) and precipitates (presumably Cu-silicides) in the Si substrate which result from the predominant in-diffusion of Cu through the TiN layer. In contrast with the case of Al, it is identified that the TiN barrier fails only the in-diffusion of Cu because there is no indication of Si pits in the Si substrate. In addition, it appears that the stuffing of TiN does not improve the diffusion barrier property in the Cu/TiN/Si structure. This indicates that in the case of Al, the chemical effect that impedes the diffusion of Al by the reaction of Al with
which is present in the grain boundaries of TIN is very improtant. On the while, in the case of Cu, there is no chemical effect because Cu oxides, such as
or CuO, is thermodynamically unstable in comparison with
. For this reason, it is considered that the effect of stuffing of TiN on the diffusion barrier property is not significant in the Cu/ TiN/Si structure.
Piezoelectric property of PZT ceramics by DC field and corona discharge poling
Park, In-Cheol ; Im, Jin-Ho ; Lee, Jun-Hyeong ; Jo, Sang-Hui ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 178~183
Piezoelectric properties of sintered specimen having a tetragonal phase of
were comparatively studied with two different poling methodes, i.e., DC field and corona discharge technique. Internal stress of poled specimens by indentation fracture toughness was analyzed to evaluate degradation phenomenon. As the results, it was confirmed that corona discharge poling technique is practicable and has merits such as low-temperature poling, slow degradation and no electric breakdown comparing to DC field poling. However, corona discharge technique showed lower Kp value than DC field poling.
Observation and Analysis of Dislocation Spacing in the Subgrain boundary on IN 617
An, Seong-Uk ; Lee, Jong-Min ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 184~190
IN 617 was crept under stresses of 107 and 180 MPa with monotonic deformation to strains of
= 0.03 - 0.30 at 1073K. In order to determine the distances between the subgrain boundaries, the deformed specimens were examined at magnifications of one hundred thousand times by TEM. In cases . where TEM observations were not possible, subgrain angles(
(b/s))were measured by Kikuchi diffraction lines. The
converted from s values measured directly by TEM agreed very well with those measured from Kikuchi lines. Therefore, it was found that the
values could be used in obtaining s, especially in cases where it is impossible to measure s by TEM.
The Effect of Processing Variables on Self-Bonding Strength in Amorphous PEEK Films
Jo, Beom-Rae ; Kardos, J.L. ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 191~196
Self-bonding strength developed at the interface of amorphous PEEK films is highly sensitive to the processing variables(time, temperature, and pressure) during the bonding process. In order to examine the effects of these processing variables, amorphous PEEK films were bonded at various bonding conditions and the resultant interfacial bond strengths were measured using a modified single lap-shear test. Experimental results showed that the developed self-bonding strength increases with increase in bonding temperature and is directly proportional to the bonding time raised to the 1/4 power. The applied pressure seems only to produce better wetting at the beginning stage of the bonding process. Conclusively, the self-bonding of amorphous PEEK films provides a great potential for developing excellent bond strength approaching the strength of the parent material without any adhesives in structural applications
Surface Morphology and Grain Growth of LPCVD Polycrystalline Silicon
Lee, Eun-Gu ; Park, Jin-Seong ; Lee, Jae-Gap ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 197~202
The surface morphology and grain growth of amophous silicon (a-Si) films deposited by low pressure chemical vapor deposition (LPCVD) have been investigated as a function of deposition and in sltu annealing condition. The film deposited at the amorphous to polycrystalline transition temperature has an extra-rough, rugged surface with (311) t.exture. At the same deposition temperature, the grain structure tends to shirr. from the polycrystalline to the amorphous phase with increasing the film thickness. It is found that nucleation of a-Si during in situ annealing at the transition temperature without breaking the vacuum starts to occur from surface Si atom migration in contrast to a heterogeneous nucleation during film deposition.
Characteristics of Low-Temperature Polysilicon Thin Film Transistors
Kim, Young-Ho ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 203~207
Polysilicon this film transistors (poly-Si TFTs) with different channel dimensions were fabricated on low-temperature crystalized amorphous silicon films and on as-deposited polysilicon films. The electrical characteristics of these TFTs were characterized and compared. The performance of the TFTs fabricated on the solid-phase crystalized amophous silicon films ws showon to be superior to that of the TFTs fabricated on the as-deposited polysilicon films. It was found that the performance of poly-Si TFTs depends strongly on the material characteristics of the polysilicon films used as the active layers, but only weakly on the channel dimensions.
The Characteristics of Wet Etch Process for Sub-micron Channel pattern with High Aspect Ratios
Lee, Chun-Su ; Choe, Sang-Su ; Baek, Jong-Tae ; Yu, Hyeong-Jun ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 208~214
In order to study on the penetrations of HF solution acording to the geometrical shrinkage of contact-hole pattern size, the wet etch characteristics for oxide in microchannel patterns was investigated. Microchannel patterns of LPCVD oxide surrounded by nitride film, with dimensions of 0.1~1
height and 0.1~20
, width, were fabricated. And the etch rates of oxide in HF solution were observed. It was found that oxide etch rate for micro-channel patterns in HF was not affected by pattern sizes and initial aspect ratios up to
size and 1.2
depth. Finally, it was concluded that there were no special limitations for penetrations of HF solution in wet processes according to the geometrical shrinkage of contact-hole pattern size.
Effects of fiber forms on thermal anisotropy in fibrous composites
Sim, Hwan-Bo ; Lee, Bo-Seong ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 215~222
Anisotropic pitch-based C-type and hollow carbon fibers can obtain wider shear stresses during the spinning and induce higher molecular orientation than that of round along the fiber axis. These fibers reinforced unidirectional epoxy composites were prepared by hot-press moulding method and perpendicular and parallel thermal conductivities of the composites were measured by a steady-state meth od. In the case of round carbon fibers reinforced epoxy composites(H-CF/EP), thermal anisotropic factor showed nearly 50, while those of H-CF/EP and C-CF/EP showed about 130 and 118, respectively. As a result, both H-CF/EP and C-CF/EP had an excellent directional thermal conductivity to distribute heat, above 200 %.
Mechanical alloying behavior of PbTe thermoelectric materials
O, Tae-Seong ; Choe, Jae-Sik ; Hyeon, Do-Bin ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 223~231
Mechanical alloying behavior of the PbTe intermetallic compound, which is used for thermoelectric generation, has been investigated with milling time and ball-to-powder weight ratio. Formation of PbTe alloy was completed by mechanical alloying of the as-mixed Pb and Te powders for 2 minutes at ball-to-powder weight ratio of 2 : 1. In situ measurement of the abrupt temperature rise during the ball milling process indicated that the PbTe intermetallic compound was formed by a self-sustained reaction rather than diffusional reactions. Lattice constant of PbTe alloy fabricated by mechanical alloying, 0. 6462nm, was not varied with milling time and ball-to-powder weight ratio. This value of the lattice parameter is in excellent agreement with 0.6459nm, which was reported for PbTe powders processed by melting and grinding.
The Determination of Stress Distribution in WC-Ni Cemented Carbide Composites by Neutron Diffraction
Seol, Kyeongwon ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 232~238
The thermal stress distribution of WC and Ni binder phases In WC-26st.%Ni and WC-6wt.%Ni composites has been investigated over the temperature range 100-900 K using a time-of-flight neutron diffractometer. To determine the stress distribution, the breadths of WC and Ni peaks in the reference powder and the composites were analyzed. The peak breadths were corrected for particle size effect using a procedure based on the integral peak breadth method of particle size-strain analysis. The result shows a broad range of strain, and thus stress, is present in the WC and Ni binder phases of the composites. The strain distribution of both phases broadens as the temperature decreases, and some fraction of total strain distribution of the WC phase remains tensile regardless of the temperature. The strain distribution of the WC phase broadens as the binder content increases, and that of Ni binder phase broadens as the binder content decreases, which means the strain distribution broadens as the absolute value of residual stress increase.
Characteristics in the Deposition of Mn-Zn Ferrite Thin Films by Ion Beam Sputtering Using a Single Ion Source
Jo, Hae-Seok ; Ha, Sang-Gi ; Lee, Dae-Hyeong ; Hong, Seok-Gyeong ; Yang, Gi-Deok ; Kim, Hyeong-Jun ; Kim, Gyeong-Yong ; Yu, Byeong-Du ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 239~245
Mn-Zn ferrite thin films were deposited on
by ion beam sputtering using a single ion source. A mosaic target consisting of a single crystal(ll0) Mn-Zn ferrite with a Fe metal strip on it was used. As-deposited films without oxygen gas flow have a wiistite structure due to oxygen deficiencies, which originated from the extra metal atoms sputtered from the metal strips during deposition. The as-deposited films with oxygen gas flow, however, have a spinel structure with (111) preferred orientation. The crystallization of thin films was maximized at the ion beam extraction voltage of 2.lkV, at which the deposited films are bombarded appropriately by the energetic secondary ions reflected from the target. As the extraction voltage increased or decreased from the optimum value, the crystallinity of thin films becomes poor owing to a weak and severe bombardment of the secondary ions, respectively. Crystallization due to the bombardment of the secondary ions was also maximized at the beam incidence angle of
. The as-deposited ferrite thin films with a spinel structure showed ferrimagnetism and had an in-plane magnetization easy axis.
Microwave Dielectric Properties of
Kim, Wang-Seop ; Kim, Gyeong-Yong ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 246~250
Microwave properties of
, MgO and CaO added
ceramics are investigated. In the composition of
, dielectric constant(
) was 22, Qxf value was 50000, and temperature coefficient of resonant frequency(
) approached to near zero
ceramics with 0.1 mol of MgO showed the highest Qxf calue of 131000, dielectric constant of 17, and r, of -
. Dielectric constant of 8 mol% CaO added to
-MgO was 20. Qxf valus was 52000, and sf was zero
-Mg0-Ca0 system showed higher Qxf value than (
) Ti03 system.
Thermoelectric properties of unidirectionally solidified
Park, Chang-Geun ; Min, Byeong-Gyu ; Lee, Dong-Hui ;
Korean Journal of Materials Research, volume 5, issue 2, 1995, Pages 251~258
In an effort to increase the thermoelectric figure of merit by reducing the thermal conductivity, the unidirectionally solidified n-type (Bi, Pb)-Te based alloys which form a
eutectic lamellar structure were investigated with the microstructural control at various solidification conditions.
lamellae were grown on cleavage plane(0001) of
and the interlamellar spacing decreased from 10.4
with growth velocity variation from
cm/sec. Seebeck coefficient was constant,
V/K regardless of growth direction, growth velocity and temperature gradient. Electrical conductivity showed a tendency to decrease slightly with growth velocity and it parallel to growth direction was about three times as large as perpendicular direction. The figures of merit were varied differently from Seebeck coefficients and electrical conductivities depending on the growth direction, growth velocity and temperature gradients. They showed the relative increase in case of perpendicular direction compared with parallel to growth direction. It is believed to be due to the reduction of the thermal conductivity according to decrease of the interlamellar spacing.