공침산화법에 의한 육방정 페라이트 $Co_2$Z(${Ba_3}{Co_2}{Fe_{24}}{O_{41}}$)의 생성

신형섭 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.11

Hexagonal ferrite $Co_2$Z(B $a_3$ $Co_2$F $e_{24}$ $O_{41}$ ) was prepared by various coprecipitation-oxidation methods. The formation of $Co_2$Z was studied in order to determine the optimal method. The $Co_2$Z composition hydroxides were prepared with the different oxidation and precipitation from the aqueous solution of $Ba^{2+}$, $Co^{2+}$ and F $e^{2+}$ chloride mixture. The coprecipitates were heat-treated at various temperatures, and their formation phases and microstructures were investigated from the analyses of DTA/TGA, powder XRD and SEM. The $Co_2$Z phase was observed in the case where the precursor will have the amorphous like oxyhydoxide($\delta$-FeOOH), and formed from $Ba_3$F $e_{32}$ $O_{51}$ , BaF $e_{12}$ $O_{19}$ (M-type) and $Ba_2$ $Co_2$F $e_{12}$ $O_{22}$ (Y-type). The $Co_2$Z was synthesized by the heat-treatment of the coprecipitate, which was prepared from the precipitation after oxidizing the chloride mixed solution, above 110$0^{\circ}C$.EX>. 육방정 페라이트 $Co_2$Z(B $a_3$ $Co_2$F $e_{24}$ $O_{41}$ )를 여러 공침-산화 방법으로 제조하여 생성과정을 연구하였으며, 적절한 제조 방법을 결정하였다. 산화 및 공침 순서를 다르게 하여 $Ba^{2+}$, $Co^{2+}$, F $e^{2+}$ 등의 염화물 혼합 수용액으로부터 $Co_2$Z 조성의 수산화물을 제조하였다. 그리고 열처리 온도에 따른 생성상의 변화를 열분석(DTA/TGA), 분말 X-선 회절분석, 주사전자현미경 등을 이용하여 관찰하였다. $Co_2$Z 상은 출발물질이 비정질에 가까운 산수산화철($\delta$-FeOOH)일 경우에만 관찰되었으며, $Ba_3$F $e_{32}$ $O_{51}$ , BaF $e_{12}$ $O_{19}$ (M형), $Ba_2$ $Co_2$F $e_{12}$ $O_{22}$ (Y형)로부터 생성되었다. 염화물 혼합 수용액을 산화시킨 다음 침전하여 합성한 공침물은 110$0^{\circ}C$부터 $Co_2$Z가 생성되었다.

A facile development of rare earth neodymium nickelate nanoparticles for selective electrochemical determination of antipsychotic drug prochlorperazine

Venkatachalam Vinothkumar,Chelliah Koventhan,Shen-Ming Chen,Yu-Feng Huang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.109 No.-

In this study, the synthesis of neodymium nickelate (Nd2NiO4, NNO) nanoparticles with diverse temperatureswere developed by the simple coprecipitation method. The successfully prepared NNO was characterizedwith various spectroscopic instruments. The surface morphology, size, shape, composition,crystallinity, functionality, bonding, and the presence of elements of the nanoparticles were analyzedby suitable characterization techniques. The electrochemical features were investigated by electrochemicalimpedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry (EIS, CV, and DPV)methods. As results expected, the modified NNO-500/SPCE sensor displays low electron transfer resistance(Rct), high active surface area, and excellent electrocatalytic activity for the detection of prochlorperazine(PCP) rather than other electrodes. Under optimized electrochemical detections, the DPV studyrevealed a low limit of detection (LoD), and limit of quantification (LoQ) of 4 nM, and 14 nM with widelinearity of 0.025–1220 mM for PCP at the NNO-500 sensor. In addition, high selectivity, stability, precision,and satisfactory recoveries in biological samples for PCP detection. Thus, our study provides a simplisticbut effective method for constructing perovskite-type materials with excellent electrochemicalperformance.

공침-산화법으로 합성된 바륨페라이트의 결정구조

신형섭 한국세라믹학회 1997 한국세라믹학회지 Vol.34 No.10

Barium ferrites (BaFe12O19) were synthesized at the various temperature by the coprecipitation-oxidation method. X-ray diffraction Rietveld analysis for barium ferrites were performed, their microstructures were observed and their magnetic properties were measured, in order to analyze the crystal structures and determine the optimal temperature of heat-treatment. The barium ferrite, its average particle size 80 nm, was formed at 600℃ through the hematite (α-Fe2O3), but the site occupations of the Fe's in tetrahedral and bipyramidal sites and of the Ba relatively low. Increasing the heating temperature, these occupations and the magnetization increased, and the crystal c-axis decreased. These changes were very small at the heat treatment of above 800℃, but the particles were rapidly grown. It is suggested that the optimal temperature of heat-treatment is 800℃, at which temperature crystal structure is relatively stable and the particles hardly ever grow.

입자 크기에 따른 ITO 후막 센서의 가스 감지 특성

신동원,이상태,전희권,이덕동,임정옥,허증수,Shin, D.W.,Lee, S.T.,Jun, H.K.,Lee, D.D.,Lim, J.O.,Huh, J.S. 한국재료학회 2003 한국재료학회지 Vol.13 No.2

Nano-sized powders of Indium Tin Oxide(ITO) were synthesized by a coprecipitation method. In order to investigate the gas sensing characteristics in the nanocrystalline ITO thick films with various particle sizes, ITO powders with the average particle diameter of 15, 30, and 70 nm respectively were synthesized. And the sensitivity of ITO thick films was measured upon exposure to a target gas($C_2$$H_{5}$ /OH) and some other Volatile Organic Compounds(VOCs), such as, toluene, methanol, benzene, chloroform. As a result, ITO thick films had high sensitivity for ethanol and higher sensitivity with smaller particle size.

The Influence of Heat Treatment on the Formation and Transport Current Density of DyBa2Cu3O7-δ Ceramics Superconductor Synthesized from Nano-Coprecipitated Powders

Imad Hamadneh 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.3

DyBa2Cu3O7-δ superconducting ceramic has been prepared from nano metal oxalate precursors with average grain size <30 nm using the coprecipitation method. Four sintering temperatures were applied for the same time period. XRD showed a single phase of an orthorhombic structure for all samples with small amount of 211 phase which was detected for samples sintered above 930°C. The sintered samples also exhibited metallic behaviour with TC(R=0) = 89 K - 90 K and the transport critical current density (JC) values enhanced from 4.35 A/cm2 to 12.9 A/cm2 as the sintering temperature increased. The SEM micrographs showed grains of large size that are randomly distributed and have irregular structure. The compaction between the grains was improved as sintering temperature increased and thus resulted in reducing the weak links effect. In conclusion, Reducing the gaps between the grain and the formation of 211 phase as pinning centers might be explain the enhancement in the transport current properties of Dy123 in a way to be used in the HTSC device applications.

공침법에 의한 Ni-Zn Ferrite의 제조 및 물성연구

정구은,고재귀,Jung Goo Eun,Koh Jae Gui 한국재료학회 2004 한국재료학회지 Vol.14 No.5

Ni-Zn ferrite powder was obtained by wet method that was to be coprecipitated the metal nitrates, Fe($NO_3$)$_3$ㆍ$9H_2$O, Ni($NO_3$)$_2$ㆍ$6H_2$O, Zn($NO_3$)$_2$ㆍ$6H_2$O to make a high permeability material. The composition of the ferrite powder was $Fe_2$$O_3$ 52 mol%, NiO 14.4 mol%, ZnO 33.6 mol%. Ni-Zn ferrite powder was compounded by precipitating metal nitrates with NaOH in vessel at the synthetic temperature of $90^{\circ}C$ for 8 hours. Calcination temperature and sintering temperature were $700^{\circ}C$ and $1150^{\circ}C$~$1250^{\circ}C$, respectively, for 2 hours. And the other ferrite powder was also prepared by the wet ball milling that was to be mixed the metal oxides as same as the above chemical composition. We studied the properties of the powder and the electromagnetic characteristics of the sintered cores obtained from there two different processes. Wet direct process produced smaller particle size with narrower distribution of the size and more purified ferrite whose sintered cores had high permeability and high magnetization.

공침법에 의한 $\delta$-FeOOH의 제조 및 자기 특성

김성재,김태옥 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.3

$\delta$-FeOOH was prepared by rapid oxidation method of Fe(OH)2 using H2O2. The effects of reaction temperature and mole ratio ([OH-]/[Fe2+])의 몰비를 제조 변수로 하여 최종 생성된 $\delta$-FeOOH의 입자크기 입자형태, 자기특성을 조사하였다. Fe(OH)2 의 반응온도 및 [OH-]/[Fe2+] 비가 $\delta$-FeOOH의 입자크기 및 형상에 많은 영향을 미침을 알수 있었으며 입자 크기는 이 두인자에 비례하여 증가하였다 Fe(OH)2 의 반응온도가 4$0^{\circ}C$ [OH-]/[Fe2+]=5 Fe(OH)2 숙성 시간 2시간에서 제조된 $\delta$-FeOOH를 TEM, VSM으로 입자의 크기 및 자기특성을 조사한결과 평균 입경이 630$\AA$ 정도이고 입도 분포가 양호하였으며 포화자화 및 보자력은 각각 20.8emu/g 210 Oe였다.

PREPARATION OF 3 MOL.% YTTRIA-FULLY-STABILIZED ZIRCONIA NANOPOWDERS BY MOLTEN SALTS/COPRECIPITATION METHOD AT LOW TEMPERATURE

YIQUN DENG,BIN YANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.2

In this paper, we present a facile process for preparing 3 mol.% yttria-fully-stabilized zirconia (3Y-FSZ) nanopowders by molten salts/coprecipitation method at low temperature. By this method, precursor powders in molten salts have a high reactivity and diffusivity, and react easily and completely, which can greatly reduce the synthesis temperature. Furthermore, the synthesis procedure involves neither mechanical mixing nor repeated grinding and thus ultrapure nanopowders with a better uniformity and fewer agglomerates can be obtained. The results illustrated that 3Y-FSZ nanopowders particle diameters ranging from 7 nm to 10 nm were successfully synthesized at 500°C.

공침법으로 합성한 이트리아 부분안정화 지르코니아 나노분말의 특성

윤혜온 ( Hye On Yoon ),신미영 ( Mi Young Shin ),안중재 ( Joong Jae Ahn ) 한국광물학회 2006 광물과 암석 (J.Miner.Soc.Korea) Vol.19 No.2

Low Temperature Sintering and Electrical Properties of Sr₂Nb₂O_(7) Ceramics by the Chemical Coprecipitation Method

Park, In Ho,Nam, Hyo Duk,Lee, Hee Yeoung 경북대학교 센서기술연구소 1995 센서技術學術大會論文集 Vol.6 No.1

Strontium niobate, Sr_(2)Nb_(2)O_(7), was prepared by the chemical coprecipitation method at low temperatures, using Sr_(2)Cl_(2)6H_(2)O, NbCI_(5) and HO_(2)CCO_(2)H. The foil nation of Sr_(2)Nb_(2)O_(7) occurred at 800℃ via an intermediate phase of composition, close to that of Sr_(5)Nb_(4)O_(15) at 700℃. The resulting powder was observed to have finer and a more uniform partical size distribution, as compared to those obtained through conventional methods, These powder characteristics allowed the use of a much lower sintering temperature of 1400℃, without sacrificing the desired dielectric and piezoelectric properties. Grain-orientation along <0k0> direction, which is a cause for improved electrical properties, was also observed.