나노세공 보에마이트의 합성 및 그 특성평가

김호건,김태용,Kim Ho-Kun,Kim Tae-Young 한국분말야금학회 2005 한국분말재료학회지 (KPMI) Vol.12 No.3

Boehmite (AlOOH) powder with uniform pore size and high specific surface area were synthesized via sol-gel method using metal salts, $Al_2(SO_4)_3$ and $NaAlO_2$. During these synthetic process, the effects of the aging time were investigated to determine the optimal synthetic conditions of boehmite. X-ray diffraction, BET, Raman/IR, and scanning electron microscopy techniques were used for the characterization of the powder. Boehmite gel synthesized at the first stage of the experimental procedure transformed to crystalline boehmite phase after aging for 6 hours. The specific surface area of the crystalline boehmite showed a maximum value, $350m^2/g$, at aging time of 72 hours. The pore size of the boehmite increased with increasing aging time and the boehmite with average pore diameter of 3.6 nm was obtained at aging time of 96 hours.

융액법에 의한 전기광학 단결정 육성

김호건 ( Kim Ho-kun ) 한국공업화학회 1990 한국공업화학회 연구논문 초록집 Vol.1990 No.0

특별강연 - 촉매 및 무기공업화학 : 융액법에 의한 전기광학 단결정 육성

김호건 ( Ho Kun Kim ) 한국공업화학회 1990 한국공업화학회 연구논문 초록집 Vol.1990 No.3

초임계 유체내의 나프탈렌의 용해도

김정림,김호건,경진범,Jeong-Rim Kim,Ho-Kun Kim,Jin-Burm Kyong 대한화학회 1988 대한화학회지 Vol.32 No.4

임계점 이상의 여러 온도와 압력에서 암모니아내의 나프탈렌의 용해도를 측정함으로써 용해도와 암모니아의 밀도 사이의 관계를 간단한 식으로 나타낼 수 있었다. 이 식을 이용하여 더 높은 압력이나 더 낮은 압력에서의 용해도를 계산할 수가 있으며, 이로부터 용해에 수반되는 에너지 변화와 엔트로피변화를 구하고, 초임계 이산화탄소내의 나프탈렌의 용해도 자료로부터 얻어진 결과와 비교하였다. 또한 나프탈렌과 암모니아 사이의 상호작용 비리알 계수를 결정하여 나프탈렌과 이산화탄소 사이의 경우와 비교 검토하였다. The solubilities of naphthalene in ammonia could be measured at various temperatures and pressures above the critical point of ammonia to represent the relationship between the solubility and the density of ammonia at desired temperature and pressure by means of a simple equation. This equation allows a calculation of the solubilities at higher and lower pressures. Using the equation, the solution energies, the solution entropies, and the second cross virial coefficients between naphthalene and ammonia have been determined to be compared with those in the case of the dissolution of naphthalene in supercritical carbon dioxide.

나노세공 Zirconia의 합성 및 특성평가

우승식,김호건,Woo, Seung-Sik,Kim, Ho-Kun 한국분말야금학회 2007 한국분말재료학회지 (KPMI) Vol.14 No.5

Zirconia powders with nano size pores and high specific surface areas were synthesized via aqueous precipitation and hydrothermal synthetic method using $ZrOCl_28H_2O$ and $NH_4OH$ under pH=11 and ambient condition. By this reaction. zirconia hydrate $(ZrO_x(OH)_{4-2x})$ was primarily synthesized and the obtained zirconia hydrate was heat treated hydrothermally using an autoclave at various temperatures under pH=11. X-ray diffraction, Scanning electron microscopy, Energy dispersive X-ray spectroscopy, FT-IR, Raman, Particle size analysis, DTA-TG, and BET techniques were used for the characterization of the powder. The synthesized zirconia showed an amorphous phase, however, the phase was transformed to the crystalline state during the hydrothermal process. The observed crystalline phase above $160^{\circ}C$ was a mixed phase of monoclinic and tetragonal zirconia. By the BET analysis, it was found that the specific surface area was ranged in $126{\sim}276m^2/g$ and the zirconia had the cylindrical shaped pores with average diameter of $2{\sim}7nm$.

균일 침전법에 의한 은 나노 입자 합성

강원모,김호건,Kang, Won-Mo,Kim, Ho-Kun 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.5

Silver particles were synthesized from silver nitrate by homogeneous precipitation and chemical reduction methods involving the intermediate silver cyanate. The obtained silver particles were characterized by XRD, SEM, TEM, and BET. Urea which could prevent the agglomeration of the reduced silver particles was used as a homogeneous precipitator. The spherical silver particles with average particle diameter of 100 nm were obtained under the optimum reaction conditions. The optimum synthetic conditions were found as follows: reaction temperature $100^{\circ}C$, reaction time 60 min, concentration of silver nitrate $1{\times}10^{-2}$ mol, urea $5{\times}10^{-3}$ mol, and sodium citrate $8.5{\times}10^{-4}$ mol. The phase of obtained silver particles was crystalline state and the silver particles were relatively dense, which had the surface area of $0.7571\;m^{2}/g$.

졸-겔법을 이용한 은 담지 하이드록시아파타이트의 제조

문병배,김호건,Mun Byung-Bae,Kim Ho-Kun 한국분말야금학회 2005 한국분말재료학회지 (KPMI) Vol.12 No.6

In the present study, silver-doped antibacterial hydroxyapatites were successfully prepared by the sol-gel method. For the starting solution, the molar ratio of $Ca(NO_3)_2{\cdot}4H_2O, P(OC_2H_5)_3,\;C_2H_5OH,\;and\;H_O$ was set to 0.075:0.045:20:0.135; $AgNO_3$ was added to a ratio of Ag to total cation concentration of $0.5-12 mol\%$. The prepared sol was dried at $100^{\circ}C$ for 48h and heat-treated at $1000^{\circ}C$ for 2h to obtain particles in the 200-500nm size range. The product from the synthesis of silver-doped hydroxyapatite was investigated through X-ray diffraction experiments and scanning electron microscopy. The product showed high antibacterial properties, with a disinfection ratio of Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25922) over $99.9^{\circ}C$ as calculated from an antimicrobial effects evaluation by the shake flask method.

Flux 법에 의한 합성 에메랄드 단결정 육성

박선민,이철태,김호건 ( Sun Min Park,Chul Tae Lee,Ho Kun Kim ) 한국공업화학회 1996 공업화학 Vol.7 No.1

합성에메랄드[(BeO)₃(Al_(2-x)Cr_xO₃)(SiO₂)_6]단결정을 flux법에 의하여 육성하였다. 출발물질로 BeO, Al₂O₃와 SiO₂ 시약을 화학양론비로 혼합하여 사용하였다. 에메랄드 단결정의 성장 조건은 다음과 같다. 온도범위 ; 1150∼900℃, 냉각속도 ; 2, 4, 10℃/hr, 융제 ; Li₂CO₃,V₂O_5, 첨가제 ; Cr₂O₃. 에메랄드 단결정의 크기는 2, 4, 10℃/hr의 냉각속도에 의존하였다. 얻어진 에메랄드 단결정을 동정하였고, 그 결과는 다음과 같다. 즉, 결정계 ; 육방정계, 격자상수 ; a=0.921㎚, c=0.917㎚, 결정의 크기 ; 최대 0.80×0.95㎟(c×m), 방위 ; c(1000), m(101￣0). Growth of synthetic emerald[(BeO)₃(Al_(2-x)Cr_xO₃)(SiO₂)_6]single crystals was carried out by flux method. In this study, the starting materials were prepared by stoichiometric mixing of BeO, Al₂O₃ and SiO₂ as reaching components. The conditions for the growth of synthetic emerald single crystals are as follows : temperature range ; 1150∼900℃, cooling rate ; 2, 4, 10℃/hr, flux ; Li₂CO₃, V₂O_5, dopant ; Cr₂O₃ The sizes of Cr₂O₃ emerald single crystals depending on 2, 4, 10℃/ hr cooling rates. The obtained emerald single crystal was characterized and the following results were obtained : lattice parameter ; a=0.921㎚, c=0.917㎚, crystal system ; hexagonal, crystal size ; max. 0.80×0.95㎟(c×m), orientation ; c(1000), m(101￣0).

졸-겔법에 의한 TiO₂ 미분말 합성과 반응메카니즘(I): Titanium isopropoxide의 가수분해

명중재,정용선,경진범,김호건,Myung, Jung-Jae,Chung, Yong-Sun,Kyong, Jin-Bum,Kim, Ho-Kun 한국공업화학회 1996 공업화학 Vol.7 No.4

$TiO_2$ fine powders were synthesized via hydrolysis reaction of titanium isopropoxide in isopropanol solvent and the reaction rates were studied by use of UV spectroscopic method. The reactions were controlled to proceed to pseudo-first-order reaction in the presence of excess water in isopropanol solvent. The rate constants which varied with temperature and concentration of water were calculated by Guggenheim method. Reactions using $D_2O$ were also carried out to determine the catalytic character of water. n value of water molecules in transition state and the thermodynamic parameters showed that the reaction proceeded by $S_N2$ mechanism. $TiO_2$ powders synthesized in this reaction were almost spheric forms and had average particle size of $0.3{\mu}m$ diameter. Isopropanol 용매 내에서 titanium isopropoxide($Ti(O-^iPr)_4$)의 가수분해반응에 의하여 $TiO_2$ 미분말을 합성하였고 가수분해 반응 속도를 자외선분광법에 의하여 측정하였다. 반응은 $Ti(O-^iPr)_4$의 농도에 비하여 물 농도를 크게 하여 유사일차반응으로 진행시켰고, 물 농도 및 온도의 변화에 따른 반응속도상수를 Guggenheim method로 계산하였다. 또한 물의 동위원소 효과를 측정하여 반응에 참여하는 물분자의 촉매성을 확인하였다. 입도분석과 미세구조 관찰 결과, 얻어진 $TiO_2$ 미분말은 $0.3{\mu}m$정도의 입자크기를 갖는 구형의 입자로 확인되었다. 또한 반응속도로부터 전이상태에 참여하는 n value와 열역학적 파라메타를 계산한 결과, $Ti(O-^iPr)_4$의 가수분해반응은 이분자 반응인 $S_N2$ mechanism으로 진행하는 것으로 추정되었다.

자외선 여기용 청색 및 황색 형광체의 발광특성

최경재,박정규,김경남,김창해,김호건,Choi, Kyoung-Jae,Park, Joung-Kyu,Kim, Kyung-Nam,Kim, Chang-Hae,Kim, Ho-Kun 한국세라믹학회 2006 한국세라믹학회지 Vol.43 No.5

We have synthesized a $Eu^{2+}-activated\;Sr_3MgSi_2O_8$ blue phosphor and $(Sr,Ba)_2SiO_4$ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the two phosphors are clearly observed at 405 nm, 460 nm and at around 560 nm, respectively. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This blue emission was used as an optical transition of the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor. The 460 nm and 560 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the $Sr_3MgSi_2O_8:Eu$ and $(Sr,Ba)_2SiO_4$ host matrix. As a consequence of a preparation of UV White LED lamp using the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/two phosphor (1/0.2361). At this time, the CIE chromaticity was CIE x = 0.3140, CIE y = 0.3201 and CCT (6500 K).