JKACG의 제1권(1991)부터 제5권(1995)까지 발표된 논문의 검토 : (II) 박막 결정성장 연구를 중심으로

오근호,심광보,임창성 한국결정성장학회 1996 한국결정성장학회지 Vol.6 No.2

The research activities on the thin film crystal growth presented in the Journal of the Korean Association of Crystal Growth form 1991 to 1995 have been reviewed.

Flux법에 의한 초전도체 YBa2Cu3O7-x 단결정 육성

오근호,김호건,명중재 한국세라믹학회 1990 한국세라믹학회지 Vol.27 No.1

YBa2Cu3O7-x(=YBCO) single crystals were grown by flux method and the growing process of crystals was investigated. YBCO and 3BaO-7CuO composition powders were mixed by the ratio of 25 : 75(wt%), and the mixtures were melted at 105$0^{\circ}C$ in a electric furnace with no temperature-gradient. Then the melt was cooled at a rate 2-1$0^{\circ}C$/h in the above furnace. YBCO single crystal plate with average size of $1.5\times$2.0$\times$0.1㎣ were obtained in the cavities between crucible and solidified ingot, and the single crystals were oriented to <001> direction. The ingots of flux parts were analyzed by XRD and EDS for the purpose of presuming the growing process of the crystals. It was assumed that the divorced eutectic reaction, by which YBCO crystals were grown first and then BaCuO2 and CuO crystals, occured in the case of cooling rate faster than 2$^{\circ}C$/h. When the cooling rate was 2$^{\circ}C$/h, it was assumed that quasi-equilibrium eutectic reaction occured, so that YBCO, BaCuO2 and CuO crystals were grown at the same time.

JKACG의 제1권(1991)부터 제5권(1995)까지 발표된 논문의 검토 : (I) Bulk 단결정성장 연구를 중심으로

오근호,심광보,임창성 한국결정성장학회 1996 한국결정성장학회지 Vol.6 No.1

The research activities on the bulk crystal growth presented in the journal of the Korean Association of Crystal Growth from 1991 to 1995 have been reviewed.

공침법 및 염분해법에 의한 La-modified PbTiO3 요업체의 제조

이병우,오근호 한국세라믹학회 1990 한국세라믹학회지 Vol.27 No.1

La-modified PbTiO3 Powders and ceramics were prepared by coprecipitation and salt decomposition method. In this process, fine and homogeneous single phase of La-modified PbTiO3 was synthesized at lower temperature than oxide mixing method. And these powders contributed to lowering calcination temperature and rising sintering properties. The properties of these powders and the change of properties with themperature and the effect of powder properties on sintering were investigated.

콜로이드성 알루미나 분말 입자의 응집현상의 컴퓨터 시뮬레이션

김종철,오근호 한국결정성장학회 1999 한국결정성장학회지 Vol.9 No.2

Agglomeration of colloidal alumina particles in a suspension is simulated. Particles in a suspension have potential energies between them and move to decrease the summation of all the potential energies between particles. The effects of various types of potential curves on particle agglomeration were checked. Strong short range attractive energy without repulsive energy barrier makes small strong clusters with disordered network structure but weak short-range force with big repulsive energy barrier makes big agglomerates with a close packing structure. As particles are agglomerated the potential energy with strong repulsive energy barrier between agglomerates gradually decreases the importance of the repulsive energy barrier and induces a different type of agglomeration behavior.

유리 프릿트의 연화점이 저온소성용 글라스/세라믹 복합체의 소결거동에 미치는 영향

구기덕,오근호 한국결정성장학회 1998 한국결정성장학회지 Vol.8 No.4

저온소성용 글라스/세라믹 복합체 제조시 사용되는 유리 프릿트의 연화점과 유리의 함량이 소결특성에 미치는 영향에 대해 고찰하였고, 이에 따라 고밀도의 저온소성용 글라스/세라믹 복합체를 제조하였다. 유리의 함량이 증가함에 따라 복합체의 소결밀도는 증가하였고, 이때 사용되는 유리의 연화점이 낮을 경우 유리의 함량이 적은 시현의 경우에도 변형이 일어남을 알수 있었다. 유리의 연화점이 높은 유리를 사용한 시편의 경우, 유리의 함량을 증가시켜도 시편의 변형은 일어나지 않았으며, 소결밀도는 계속적으로 증가하여 치밀화가 하고 있음을 알수 있었다. 이러한 유리함량과 유리의 연화점이 소결특성에 미치는 영향을 고찰함으로써 높은 밀도의 동시소성용 글라스/세라믹을 제조할 수 있는 유리의 연화점과 유리함량을 예측할 수 있었고, 이에따라 $790^{\circ}C$의 연화점을 갖는 유리를 유리 프릿트로 사용함으로써 $900^{\circ}C$의 소성온도에서 소결밀도 97%이상의 고밀도의 저온소성용 글라스/세라믹 복합체를 제조할 수 있었다.

마이크로웨이브 magnetron sputtering법으로 제막된 ZnO:Al 박막의 전기광학적 특성

유병석,오근호 한국결정성장학회 1998 한국결정성장학회지 Vol.8 No.4

AZO transparent conducting thin film were fabricated by DC magnetron sputtering using the Zn: Al (2% aluminu contained ) alloy target with inducing microwave to the plasma, and the effect of microwave was studied. The optical transmittance, the resistivity and dynamic deposition rate at the applied voltage to target of 420 V was 50~70%, $ 5.5{\times}10^{-3}{\Omega}$cm and 6,000 $\AA\textrm{mm}^2$/J, respectively. After annealing AZO coated glass at $400^{\circ}C$ for 30 minutes, the light transmittance was increased to 80% and electrical conductivity was also increased two times, reached to resistivity of $2.0{\times}10^{-3}{\Omega}$cm.

직류 반응성 sputtering법으로 제막된 ZnO:Al 박막의 물성에 미치는 증착조건 및 타겟의 영향

유병석,오근호 한국결정성장학회 1998 한국결정성장학회지 Vol.8 No.4

AZO(Aluminum doped Zinc Oxide) thin films were fabricated by reactive DC magnetron sputtering method using zinc metal target (Al 2%) and zinc oxide target ($Al_2O_3\;2%$) respectively. The intermediate condition with optimum transmittance and conductivity was obtained by controlling the sputtering parameters. Oxygen gas ratio for this condition was $0.5{\times}10^{-2}~1.0{\times}10^{-2}$ in oxide target and. In case of metal target, this optimum oxygen gas ratio at the applied power of 0.6 kW and 1.0 kW was 0.215~0.227 and 0.305~0.315, respectively. The resistivity of AZO film deposited was obtained $1.2~1.4{\times}10^{-3} {\Omega}{\cdot}$cm as deposited state regardless of target species.

$YBa_2Cu_3O_{7-x}$초전도 단결정 성장

정광철,오근호,최종건 한국세라믹학회 1990 한국세라믹학회지 Vol.27 No.4

Single crystals of YBa2Cu3O7-x have been grown in BaCuO2 flux at temperature of 125$0^{\circ}C$ and examined using XRD, EDAX and light microscopy. The YBCO crystals were grown in a cavity which was formed by the reduction of CuO and became large by the directional solidification in the crucible. The observed crystal growth habit is square planar with the c-axis normal to the plane. The surface morphology of grown crystals were growth ledges and growth sprial paterns on a (001) face.

Floating Zone법에 의한 Mn-Zn Ferrite 단결정성장에 관한 연구

정재우,오근호 한국결정성장학회 1992 한국결정성장학회지 Vol.2 No.1

Mn - Zn Ferrite has physical properties of the high initial permeability, saturation magnetic flux density, and low loss factor as a representative magnetic material of soft ferrites, in addition the mechanical property is excellent as a single crystal. Therefore it is important electronic components and used for VTR Head. Mn - Zn Ferrite single crystals with the diameter 8mm were grown in atmosphere mixed with $O_2$ and Ar gas by the Floating Zone(FZ) method that impurities can not be incorporated to the crystals because of not-using the crucible to put in the melt, and the sharp temperature gradient results from making a focus at one point utilizing the infrared ray emitted from the halogen lamp as a heat source. During the crystal growing, the highest temperature of melting area was maintained to be $1650^{\circ}C$, growth rate and rotation rate were 10 mm/hr, 20 rpm respectively. The phases and the growth directions of crystals were determined from the analysis of X RD patterns, Laue, TEM diffraction patterns and etch pit shapes were observed by the optical microscope through the chemical etching. The corelation of optimum conditions for acquiring the better crystals was found out with the growth rate, the length and diameter of melt at the interface according to the diameter of feed rod, and the patterns of growing interface also studied.