수열합성 공정 변화에 따른 ZnS 나노분말의 구조 특성과 소결체의 광학적 특성

여서영,권태형,김창일,윤지선,정영훈,홍연우,조정호,백종후,Yeo, Seo-Yeong,Kwon, Tae-Hyeong,Kim, Chang-Il,Yun, Ji-Sun,Jeong, Young-Hun,Hong, Youn-Woo,Cho, Jeong-Ho,Paik, Jong-Hoo 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.6

In this paper, the ZnS nanoparticles were synthesized according to the process conditions of hydrothermal synthesis. When the molar ratio of Zn to S was 1:1.2, it was confirmed that it had a cubic single phase and a high crystal phase. After the molar ratio is fixed, hydrothermal synthesis was conducted at $180^{\circ}C$ for 24, 36, 72 and 96 h in order to confirm the structural change with the change of hydrothermal synthesis times. As the hydrothermal synthesis times increased, the particle size increased. The hydrothermal synthesized particle size for 72 h was considered to be suitable for sintering. The ZnS ceramic had a density of 99.7% and an excellent transmittance of ~70% in the long-wavelength region.

Copper(II) complexes with <i>N</i>-substituted aspartic acids: A new one-pot synthesis method via <i>in situ</i> Michael addition of amines to fumaric acid

Do, Junghwan,Kang, Jaeun,Lee, Yumi,Ok, Kang Min,Jacobson, Allan J. Elsevier Sequoia [etc.] 2015 Inorganica chimica acta Vol.430 No.-

<P><B>Abstract</B></P> <P>The hydrothermal reaction of fumaric acid, benzylamine and cuprous chloride yielded Cu[(<I>rac</I>-<I>N</I>-benzyl-Asp)(benzylamine)(H<SUB>2</SUB>O)] <B>1</B>, while ethylenediamine, 1,3-diaminopropane and piperazine produced Cu[<I>rac</I>-<I>N</I>-aminoethyl-Asp] <B>2</B>, Cu[<I>rac</I>-<I>N</I>-aminopropyl-Asp] <B>3</B> and Cu[<I>rac</I>-piperazinyl succinate]<SUB>2</SUB> <B>4</B>, respectively. Under mild hydrothermal conditions, Michael addition of benzylamine, ethylenediamine, 1,3-diaminopropane and piperazine to fumaric acid led to the formation of racemic mixtures of <I>N</I>-benzyl aspartic acid, <I>N</I>-aminoethyl aspartic acid, <I>N</I>-aminopropyl aspartic acid and piperazinyl succinic acid, respectively. The structure of <B>1</B> consists of one-dimensional polymeric chains in which copper cations are bridged by D- and L-<I>N</I>-benzyl aspartate anions alternatively along the chain. Additional benzylamine and water molecules bond to copper cations to complete the Cu[(<I>rac</I>-<I>N</I>-benzyl-Asp)(benzylamine)(H<SUB>2</SUB>O)] chain. The structures of <B>2</B> and <B>3</B> consist of one-dimensional polymeric chains in which copper cations are bridged by D- and L-<I>N</I>-aminoethyl and aminopropyl aspartate anions alternatively along the chains. The structure of <B>4</B> is composed of discrete Cu[<I>rac</I>-piperazinyl succinate]<SUB>2</SUB> units that are connected by hydrogen bonds.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Michael addition of amines to fumaric acid hydrothermal synthesis. </LI> <LI> <I>in situ</I> synthesis of <I>N</I>-substituted aspartic acid copper complexes. </LI> <LI> Crystal structures of four new copper(II) aspartates. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Copper aspartates synthesized by in-situ Michael addition of amines to fumaric acid under hydrothermal reaction conditions.</P> <P>[DISPLAY OMISSION]</P>

니켈 폼(Ni foam)에 수열 합성법으로 제조한 수산화니켈(Ni(OH)2) 전극의 구조적 및 전기적 특성

차현진,이석희,박정환,손영국,황동현 한국표면공학회 2023 한국표면공학회지 Vol.56 No.5

In this study, the nickel hydroxide (Ni(OH)2) electrode for supercapacitor was prepared via hydrothermal method. Based on the nickel (Ni) foam, the electrode does not require any additional binder material or post-processing. Nickel nitrate (Ni(NO3)2) and hexamethylenetetramine (C6H12N4) were used for synthesis, and the synthesis condition was 12 hours at 80 °C. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) were used to analyze the structural characteristics of the electrode, and it shown that the nickel hydroxide was successfully prepared after only the one-step hydrothermal synthesis. The electrochemical properties were analyzed through the half-cell test. The prepared electrode shown a pair of oxidation/reduction peaks, indicating that the driving method included the redox reaction on the electrode surface. After the charge/discharge test, the specific capacitance was calculated as the value of 438 F/g at 3 A/g.

Open System 수열반응을 통한 하수슬러지 소각 비산재의 Zeolite 합성가능성

이제승,엄석원,최한영,Lee, Je-Seung,Eom, Seok-Won,Choi, Han-Young 한국환경보건학회 2007 한국환경보건학회지 Vol.33 No.4

The sewage treatment sludge disposal has become a serious environmental problem because of restricted direct land-filling and oceandumping in spite of their large amounts discharged. So the recycling of sewage treatment sludge is very useful alternative for waste management. Here, we studied the feasibility of zeolite synthesis in open system from the sewage treatment sludge incinerator fly ash by means of hydrothermal synthesis. We considered the concentration of NaOH, reaction time, reaction temperature and reaction step as synthesis variables. The phase of zeolite products was identified by X-ray diffractometer(XRD) and ammonium ion exchange test was performed for the raw fly ash and two zeolite products(Z-3 and Z-5). In leaching test of the raw fly ash, hazard metal is detected very low level compared with regulatory leaching test standard. But in total recoverable test, the total contents of the fly ash were very high in terms of the standard for waste-derived fertilizer. Through hydrothermal reaction, small amount of zeolite P was synthesied in 1 N of NaOH solution and relatively large amount of hydroxysodalite was synthesied in 3 N and 5 N of NaOH solution with similar peak intensity. Addition of an aging step in the synthesis didn't increase the amount of zeolite phase. Maximum $NE_4^+-N$ exchange capacity is 1.49 mg $NH_4^+-N/g$ in Z-3 and 1.38 mg $NH_4^+-N/g$ in Z-5. Most of the ammonium ion is exchanged in 30 minutes and disorption did not occur until 5 hours.

수열합성법을 이용한 전이금속 도핑 TiO(2) 합성 및 광분해 효율

최승현 ( Seung Hyun Choi ) 조선대학교 공학기술연구원 2014 공학기술논문지 Vol.7 No.2

Metal (Ag, Ce, Fe, V, Zr and Zn) doped TiO2 nanoparticles were fabricated by a sol.gel method and an alkali hydrothermal synthesis. The mole ratio of TTIP, IPA, and distilled water were adjusted while the doped TiO2 powders were treated at 170℃-200℃ for 8 hours via the hydrothermal synthesis. The synthesized Metal doped TiO2 nanoparticles were thoroughly characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy in order to determine their morphology, structural and electronic properties. Theas-prepared catalysts were evaluated in the photo decomposition of methylene blue under UV light. The photodegradation efficiency of the doped TiO2 with Fe ions and Ag ions was the best among the samples. And the sharp decrease of the efficiency was identified as the concentration went above a certain level. It was found that the photodegradation efficiency of TiO2 which contained some rutile-type was a little higher than pure anatase-type and the photodegradation efficiency decreased when the ratio of anatase-rutile was 8:2.

Control of particle morphology and size of yttria powder prepared by hydro(solvo)thermal synthesis

오복현,이상진 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.4

Yttria (Y 2 O 3 ) is a representative material having excellent plasma resistance, and yttria powder, applied to semiconductor components and thermal spray coating, requires excellent sinterability and fl owability, for which particle shape and size are important factors. In the present study, to synthesize yttria powder having various shape applicable to many industrial areas, the morphology of yttria particles was controlled through hydro(solvo)thermal synthesis. The yttria powder was synthesized using deionized water, ethylene glycol and glycerol as solvents. The precursor concentrations and the synthesis conditions such as synthesis temperature and time were examined. The particle shape and size of the yttria powder were adjusted to plate-type, rod-type and spherical-type depending on the applied solvent, precipitant and synthesis temperature. The thermal treatment following the hydro(solvo)thermal synthesis did not have a signifi cant eff ect on the shape of the yttria particles. Cubic single-phase yttria was observed at a calcination temperature of 450 °C or higher, and the crystal phase further devel- oped as the thermal treatment temperature increased. In the powder synthesized using deionized water, the crystal phase developed mostly on the [222] direction depending on the temperature during oriented attachment. On the other hand, in the powder synthesized using ethylene glycol and glycerol as a solvent, the crystal phase developed homogeneously in all crystalline directions.

수열 합성에 의해 제조된 다공성 Wollastonite Ceramics의 특성

김병훈,나용한 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.8

The porous wollastonite ceramics were fabricated after firing calcium silicates, obtained using natural resources and by-products of power plants by hydrothermal synthesis, without organic fibers or asbestos for reinforcement agent. A specimen from diatomite as a SiO2 staring raw material had the highest strength owing to normal grain growth and good densification from homogeneous sperhcial C-S-H hydrates. A specimen from SiO2 sol as a SiO2 starting raw material showed tobermolite, but fly ash and mixed system did xonotlite after hydrothermal synthesis. The specimen from fly ash showed the lowest firing shirikage and strength changes in the firing range from 50$0^{\circ}C$ to 120$0^{\circ}C$. The other phases in all specimens changed to wollastonite phase after firing at 100$0^{\circ}C$. Also the average pore size was distributed from 0.2${\mu}{\textrm}{m}$ to 2${\mu}{\textrm}{m}$.

Effects of pH Value, Reaction Time, and Filling Pressure on the Hydrothermal Synthesis of ZnFe₂O₄ Nanoparticles

Yoo, Pil Sun,Lee, Bo Wha,Liu, Chunli IEEE 2015 IEEE transactions on magnetics Vol.51 No.11

<P>We investigated the effect of the pH value, reaction time, and filling pressure on the preparation of ZnFe<SUB>2</SUB>O<SUB>4</SUB> (ZFO) nanoparticles using a hydrothermal synthesis. X-ray diffraction showed that all three parameters should be controlled in order to prepare ZFO nanoparticles without impurities. Furthermore, the nanoparticle size reduced from 60 to 5 nm when the filling pressure was increased from 50% to 70%. The X-ray photoelectron spectroscopy showed that the ZFO nanoparticles actually possess a mixed spinel structure due to the coexistence of Fe<SUP>2+</SUP> and Fe<SUP>3+</SUP>, and there were significant amounts of oxygen vacancies near the surface. The cation inversion and surface effect worked together to determine the magnetic properties of the ZFO nanoparticles. The ZFO nanoparticles of 60 nm sizes showed a much enhanced room temperature ferromagnetism together with a larger coercivity compared with that of the ZFO nanoparticles of 5 nm sizes. Our results provide valuable information regarding the optimization of the hydrothermal synthesis of ferrite nanoparticles for desired applications.</P>

A selective morphosynthetic approach for single crystalline hematite through morphology evolution via microwave assisted hydrothermal synthesis

Kim, C.W.,Kang, M.J.,Van, T.K.,Kang, Y.S. Korean Society of Industrial and Engineering Chemi 2017 Journal of industrial and engineering chemistry Vol.53 No.-

Hematite single crystals are one of most promising materials which is able to apply for the field of catalyst industry. Even its prospective applicability, strategies for improving its catalytic performance are still not enough to meet the requirements for industrial application. In the present work, we demonstrate a morphology selective one pot reaction for a hematite single crystal by microwave-assisted hydrothermal synthesis. The microwave-assisted hydrothermal route, taking advance of the exposed crystal facet-based activity of the material, is suggested to crystal facet controlling synthesis of the hematite crystal. The dispersant and capping agents such as sodium carboxymethyl cellulose and N<SUB>2</SUB>H<SUB>4</SUB>, respectively, play a very important role in controlling the exposed crystal facet and morphological uniformity for a selective morphology of hematite crystal. In addition, systematically experimental examination of the well-exposed facet is interestingly giving an insight into the crystal growth and morphological evolution of single crystalline hematite from plate to tetrahexagonal bipyramid, octahedral and oblique cubic shape. Physicochemical techniques were used to characterize and evaluate the photoactivity of the material in detail. In here, a well-defined crystal facet is obtained and expected to be applied as an efficient catalysts and its synthetic methodology is applicable to other metal oxide photocatalyst.

A selective morphosynthetic approach for single crystalline hematite through morphology evolution via microwave assisted hydrothermal synthesis

김창우,강명종,Thanh Khue Van,강영수 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-

Hematite single crystals are one of most promising materials which is able to apply for the field of catalyst industry. Even its prospective applicability, strategies for improving its catalytic performance are still not enough to meet the requirements for industrial application. In the present work, we demonstrate a morphology selective one pot reaction for a hematite single crystal by microwave-assisted hydrothermal synthesis. The microwave-assisted hydrothermal route, taking advance of the exposed crystal facetbased activity of the material, is suggested to crystal facet controlling synthesis of the hematite crystal. The dispersant and capping agents such as sodium carboxymethyl cellulose and N2H4, respectively, play a very important role in controlling the exposed crystal facet and morphological uniformity for a selective morphology of hematite crystal. In addition, systematically experimental examination of the wellexposed facet is interestingly giving an insight into the crystal growth and morphological evolution of single crystalline hematite from plate to tetrahexagonal bipyramid, octahedral and oblique cubic shape. Physicochemical techniques were used to characterize and evaluate the photoactivity of the material in detail. In here, a well-defined crystal facet is obtained and expected to be applied as an efficient catalysts and its synthetic methodology is applicable to other metal oxide photocatalyst.