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제1장 서론 12

제2장 이론적 고찰 18

2.1. 산화철 및 수산화철의 제조방법 및 용도 18

2.2. 산화철의 특성 24

참고문헌 29

제3장 황산제일철/황산제이철을 이용한 산화철 합성 37

3.1. 서론 37

3.2. 실험 및 재료 38

3.2.1. 시약 38

3.2.2. 실험방법 39

3.3. 결과 및 고찰 40

3.3.1. pH 변화 40

3.3.2. 결정상 분석 47

3.3.3. 상평형도 51

3.3.4. 미세조직 및 입도분석 55

3.4. 결론 58

참고문헌 59

제4장 Fe₃O₄ 생성에 미치는 황산제일철/황산제이철 몰비의 영향 61

4.1. 서론 61

4.2. 실험 및 재료 62

4.2.1. 시약 62

4.2.2. 합성 및 분석 63

4.3. 결과 및 고찰 64

4.3.1. 황산제이철의 화학조성 64

4.3.2. 당량비의 영향 66

4.3.3. 몰비의 영향 74

4.4. 결론 81

참고문헌 82

제5장 Fe₃O₄ 생성에 미치는 황산제일철/황산제이철 몰비와 침전제의 영향 85

5.1. 서론 85

5.2. 실험방법 86

5.2.1. 시약 86

5.2.2. 합성 및 분석 87

5.3. 결과 및 고찰 88

5.3.1. 미세구조 및 입자크기 88

5.3.2. 결정상 및 결정자 크기 92

5.3.3. 자기적특성 99

5.4. 결론 104

참고문헌 105

ABSTRACTS 108

PUBLICATIONS 112

표목차

Table 2-1. Compounds of oxides obtained from aqueous solutions and suspensions 27

Table 3-1. Crystallite size(nm) of magnetite depending on equivalent ratio of NH₄OH/Fe sulfate and reaction temperature 50

Table 3-2. Results of the Rietveld analysis depending on equivalent ratio of NH₄OH/Fe sulfate and reaction temperature 52

Table 4-1. Properties of precipitates obtained with various molar ratio of FeSO₄/Fe₂(SO₄)₃ at an equivalent ratios of 3.0 for NaOH/Fe sulfate 79

Table 5-1. Summary on properties of precipitates depending on precipitants and FeSO₄/Fe₂(SO₄)₃ molar ratio at an equivalent ratio 3.0 of precipitants/Fe sulfate 98

그림목차

Fig. 2-1. Schematic diagram of oxidation and reduction reactions in iron oxides 28

Fig. 3-1. Variation of reaction solution pH change with reaction temperature at different equivalent ratios of NH₄OH/Fe sulfate (a) 0.1, (b) 0.25, (c) 0.5, (d) 0.65, (e) 0.75, (f) 1.0 and (g) 2.0. 41

Fig. 3-2. Variation of reaction solution pH with equivalent ratios of NH₄OH/Fe sulfate after 30 minute reaction at different temperatures 46

Fig. 3-3. XRD patterns of precipitates obtained at 25℃ with various equivalent ratio of NH₄OH/Fe sulfate (a) 0.1, (b) 0.25, (c) 0.4, (d) 0.5, (e) 0.6, (f) 0.75, (g) 1.0, (h) 2.0, (i) 3.0 48

Fig. 3-4. Equilibrium phase diagram of the synthesized iron oxides using ferrous sulfate, ferric sulfate and ammonia water. ▼ jarosite, ○ jarosite + goethite, ● goethite,... 53

Fig. 3-5. Equilibrium phase diagram of the synthesized iron oxides using ferrous sulfate and ammonia water. 54

Fig. 3-6. SEM images and their size distribution of magnetite particles obtained with equivalent ratio 0.75, 1.0, and 2.0 for NH₄OH/Fe sulfate at reaction temperature of 25℃. 56

Fig. 3-7. Median sizes depending of magnetite particles obtained with various equivalent ratios for NH₄OH/Fe sulfate at different reaction temperatures. 57

Fig. 4-1. TG-DSC spectra of ferric sulfate hydrate. 66

Fig. 4-2. XRD patterns of precipitates obtained equivalent ratios a) 1.0, (b) 2.0, (c) 3.0, and (d) 4.0 NaOH with a molar ratio FeSO₄/Fe₂(SO₄)₃ was fixed at 1.0. 67

Fig. 4-3. SEM images of precipitates obtained with equivalent ratios (a) 1.0, (b) 2.0, (c) 3.0 and (d) 4.0 for NaOH, at a molar ratio of FeSO₄/Fe₂(SO₄)₃ was fixed at 1.0. 71

Fig. 4-4. Magnetization curves of precipites obtained with equivalent ratios (a) 1.0, (b) 2.0, (c) 3.0 and (d) 4.0 for NaOH at a molar ratio of FeSO₄/Fe₂(SO₄)₃ was fixed at 1.0.... 73

Fig. 4-5. XRD patterns of precipitates obtained with FeSO₄/Fe₂(SO₄)₃ molar ratios (a) 1.0, (b) 1.25, (c) 1.67, (d) 2.5 and (e) 5.0, at an equivalent ratio 3.0 of NaOH/Fe sulfate. 76

Fig. 4-6. Size distribution and its median size of precipitates obtained with FeSO₄/Fe₂(SO₄)₃ molar ratios (a) 1.0, (b) 1.25, (c) 1.67, (d) 2.5. and (e) 5.0. 78

Fig. 4-7. Magnetization curves of precipites obtained with FeSO₄/Fe₂(SO₄)₃ molar ratio (a) 1.0, (b) 1.25, (c) 1.67, (d) 2.5, and (e) 5.0 at an 3.0 for NaOH/Fe sulfate.... 80

Fig. 5-1. SEM images of precipitates depending on precipitant (a) NaOH and (b) NH₄OH regardless of FeSO₄/Fe₂(SO₄)₃ molar ratios The equivalent ratio precipitant/Fe sulfate was fixed at 3.0. 89

Fig. 5-2. Particle size distribution of precipitates obtained with various FeSO₄/Fe₂(SO₄)₃ molar ratios and precipitants at an equivalent ratio 3.0 of precipitant/Fe sulfate. 90

Fig. 5-3. Various median particle sizes for precipitates with molar ratio of FeSO₄/Fe₂(SO₄)₃ molar ratio at different precipitants (a) NaOH and (b) NH₄OH and an equivalent ratio 3.0 of precipitant/Fe sulfate 91

Fig. 5-4. XRD patterns of precipitates obtained with FeSO₄/Fe₂(SO₄)₃ molar ratios (a) 1.0, (b) 1.25, (c) 2.5, and (d) 5.0 at an equivalent ratio 3.0 of NaOH/Fe sulfate.... 94

Fig. 5-5. XRD patterns of precipitates obtained with FeSO₄/Fe₂(SO₄)₃ molar ratios (a) 1.0, (b) 1.25, (c) 2.5, and (d) 5.0 and at an equivalent ratio 3.0 of NH₄OH/Fe sulfate. 95

Fig. 5-6. Variation of XRD intensity for precipitates with FeSO₄/Fe₂(SO₄)₃ molar ratio at different precipitant (a) NaOH, and (b) NH₄OH and at an equivalent ratio 3.0 of precipitants/Fe... 96

Fig. 5-7. Various of Crystallize size for precipitates with FeSO₄/Fe₂(SO₄)₃ molar ratio at different precipitants (a) NaOH and (b) NH₄OH and an equivalent ratio 3.0 of precipitants/Fe... 97

Fig. 5-8. Magnetization curves of precipitares obtained with results FeSO₄/Fe₂(SO₄)₃ molar ratio (a) 1.0, (b) 1.25, (c) 2.5 and (d) 5.0 and at an equivalent ratio 3.0 of NaOH/Fe sulfate. 100

Fig. 5-9. Magnetization curves of precipitares obtained with results FeSO₄/Fe₂(SO₄)₃ molar ratio (a) 1.0, (b) 1.25, (c) 2.5 and (d) 5.0 at an equivalent ratio 3.0 of NH₄OH/Fe sulfate. 101

Fig. 5-10. Various of saturated magnetization for precipitates with FeSO₄/Fe₂(SO₄)₃ molar ratio at different precipitants (a) NaOH and (b) NH₄OH at an equivalent ratio 3.0 of... 102

Fig. 5-11. Correlationship between saturated magnetization and crystallite size for precipitates obtained with different molar ratios of FeSO₄/Fe₂(SO₄)₃ and precipitants NaOH(■) and... 103

초록보기

1. Synthesis of iron oxide using ferrous and ferric sulfate

The effect of co-precipitation parameters on the formation of iron oxide wasinvestigated using ferric sulfate, ferrous sulfate and ammonia water jarosite phase was formed when the equivalent ratio of NH₄OH/Fe sulfate was 0.1~0.25 and jarosite, goethite and magnetite phase were formed when the equivalent ratio was 0.25~0.6. Single-phase magnetite was able to be formed when the equivalent ratio was above 0.65.

The crystallite size and median particle size of the magnetite was decreased with increasing equivalent ratio from 0.65 to 2.0. Its sizes were increased with increasing reaction temperature from 25 ℃ to 75 ℃.

The synthetic conditions to get of the magnetite single phase became simpler when ferric and ferrous sulfate was used together than ferrous sulfate was used alone due to co-existence of Fe²+ and Fe³+ in the solution.

2. Effect of molar ratio of ferrous/ferric sulfate on the formation of Fe₃O₄

The effect of FeSO₄/Fe₂(SO₄)₃ molar ratio on the formation of nano-sized magnetite particles was investigated by co-precipitation method. Ferrous sulfate and ferric sulfate were used as iron sources and sodium hydroxide was used as a precipitant. The experimental conditions were varied with FeSO₄/Fe₂(SO₄)₃ molar ratio of 1.0 to 5.0 NaOH/Fe sulfate and equivalent ratios of 1.0 to 4.0, while reaction temperature and time were fixed at 25℃ and 30min, respectively. To prevent oxidation of Fe²+ by air, argon gas was flowed during the reaction.

The single phase magnetite was synthesized with the equivalent ratios of above 2.0 and all of FeSO₄/Fe₂(SO₄)₃ molar ratios. The crystallinity was higher with increasing equivalent ratios up to 3.0. The crystallite size of 5.6 to 11.6 nm, median particle size of 15.4 to 19.5 nm and saturation magnetization of 43 to 71 emu/g were varied with FeSO₄/Fe₂(SO₄)₃ molar ratio. The highest saturation magnetization value was obtained with 71 emu/g at equivalent ratio of 3.0 and the FeSO₄/Fe₂(SO₄)₃ molar ratio of 2.5.

3. Effect on the molar ratio of ferrous FeSO₄/Fe₂(SO₄)₃ and precipitants of NaOH and NH4OH formation of Fe₃O₄

The effect of FeSO₄/Fe₂(SO₄)₃ molar ratio and precipitant on the formation of nano-sized magnetite particles was investigated by co-precipitation method. Ferrous sulfate and ferric sulfate were used as iron sources and sodium hydroxide and ammonium hydroxide was used as a precipitant. The experimental conditions were varied with FeSO₄/Fe₂(SO₄)₃ molar ratio of 1.0 to 5.0, while precipitants/Fe sulfate equivalent ratio and reaction temperature and time were fixed at 3.0, 25℃ and 30 min, respectively. To prevent oxidation of Fe²+ by air, argon gas was flowed during the reaction.

The single phase magnetite was synthesized with various experiment conditions (molar ratios of FeSO₄/Fe₂(SO₄)₃, precipitants NaOH and NH₄OH). The particle size was smaller and its distribution was narrower when NaOH was used instead of NH₄OH. The crystallinity was better and the particle size was gradually increased and more narrowly distributed with increasing FeSO₄/Fe₂(SO₄)₃ molar ratios at the same precipitant. The formed magnetite particles were superparamagnetic at all of experiment conditions. The highest saturation magnetization value was obtained with 72 emu/g at the FeSO₄/Fe₂(SO₄)₃ molar ratio of 2.5 and the precipitant of NH₄OH.

참고문헌 (19건) : 자료제공( 네이버학술정보 )

참고문헌 목록에 대한 테이블로 번호, 참고문헌, 국회도서관 소장유무로 구성되어 있습니다.
번호 참고문헌 국회도서관 소장유무
1 Journal of Magnetism and Magnetic Materials, 310 2375 – 2377. (2007) 미소장
2 Journal of Colloid and Interface Science, 305,366 – 370 (2007). 미소장
3 Current Applied Physics, 8, 758 – 760(2008). 미소장
4 Journal of Magnetism and Magnetic Materials, 284, 145 – 160(2004). 미소장
5 Journal of Magnetism and Magnetic Materials, 289, 25 – 27(2005). 미소장
6 Journal of Magnetism and Magnetic Materials, 321, 3019 – 3023(2009). 미소장
7 Solid State Ionics, 172, 217 – 220(2004). 미소장
8 ElectrochimicaActa, 53, 3436 – 3441(2008) (2008). 미소장
9 Materials Research Bulletin, 36, (2001) 497 – 502(2001). 미소장
10 Materials letters: Low-temperature preparation of perovskite Pb(Sc 0.5Ta 0.5)O 3 thin films using MOCVD (28 (1996) 17) 네이버 미소장
11 Colloids and Surfaces A: Physicochemical and Engineering, Aspects139, 279 – 285(1998). 미소장
12 NanoStructured Materials, 8, 657 – 673(1997). 미소장
13 Journal of Alloys and Compounds, 472, 18 – 23 (2009). 미소장
14 Materials Research Bulletin , 41, 703 – 713(2006). 미소장
15 Journal of Magnetism and Magnetic Materials, 322, 400 – 404(2010). 미소장
16 Materials Letters, 62, 4155 – 4157(2008). 미소장
17 Journal of Non-Crystalline Solids, 353 829 – 831(2007). 미소장
18 Materials Letters, 61, 4447 – 4451(2007). 미소장
19 Korean Journal of Materials Research, 21, 225-231(2011) 미소장

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