표제지
목차
국문초록 14
Ⅰ. 서론 16
Ⅱ. 문헌연구 20
1. 페라이트의 결정구조 20
1.1. M-type 헥사 페라이트 23
1.2. W-type 헥사 페라이트 26
2. 자성체의 자기적 특성 29
2.1. 포화자화 30
2.2. 보자력 31
2.3. 이방성 필드 34
3. 합성 방법 36
Ⅲ. 실험방법 37
1. 고상합성법 37
1.1. M-type 헥사 페라이트의 합성 39
1.2. W-type 헥사 페라이트의 합성 41
2. 특성 분석 43
2.1. 결정구조 및 상 분석 43
2.2. 미세구조 관찰 44
2.3. 소결밀도 측정 44
2.4. 자기적 특성 45
Ⅳ. 실험결과 및 고찰 46
1. M-type 헥사 페라이트 (Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ)[이미지참조] 46
1.1. 구조적 특성 분석 46
1.2. 미세구조 및 소결밀도 분석 54
1.3. 자기적 특성 분석 61
2. W-type 헥사 페라이트 (Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇) 71
2.1. 구조적 특성 분석 71
2.2. 미세구조 및 소결밀도 분석 79
2.3. 조성 변화에 따른 자기적 특성 분석 81
Ⅴ. 요약 및 결론 88
Ⅵ. 참고문헌 90
ABSTRACT 94
Table 2.1. Comparison of various descriptions of the unit cells of hexagonal ferrites. * = 180 rotations of that block around the c-axis. 22
Table 2.2. Position and spin direction of Fe ions in M-type hexaferrite 24
Table 2.3. Position and spin direction of Fe ions in W-type hexaferrite 27
Table 2.4. Comparison of magnetic properties of hexaferrite at room temperature. Hc varies so much with processing method and particle size...[이미지참조] 35
Table 4.1. Rietveld refined structure parameters a, c, c/a, and Vcell with fitting parameters Rwp of Ca₀.₁₅ Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1100℃, 1150℃, 1200℃[이미지참조] 52
Table 4.2. Densities and relative densities of Ca₀.₁₅ Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1100℃, 1150℃, 1200℃[이미지참조] 59
Table 4.3. Magnetic properties (Mₛ, Hc, Hₐ), A, R² with calculated field regions of Ca₀.₁₅ Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1100℃, 1150℃, 1200℃[이미지참조] 68
Table 4.4. Phases, Rietveld refined structure parameters a, c, c/a, and V cell with fitting parameters Rwp of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn)[이미지참조] 77
Table 4.5. Densities and relative densities of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn) 79
Table 4.6. Magnetic properties Mₛ, Hc, and Hₐ with calculated field regions of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn)[이미지참조] 86
Figure 1.1. Development of room temperature energy density (BH)ₘₐₓ of hard magnetic materials in the 20th century and emergence of various materials 18
Figure 1.2. Pseudo-binary state diagram in air Fe-rich fraction of SrO- Fe₂O₃ (>33 mol% Fe2O3). (M = SrFe₁₂O₁₉, W = SrFe₁₈O₂₇, X = Sr₂Fe₃₀O₄₆... 19
Figure 2.1. Perspective view and space filling view of S, R and T blocks 21
Figure 2.2. (a) Crystal structure of M-type hexaferrite unit cell: Red, gray, and yellow represents Sr/Ba, O, and Fe atoms... 25
Figure 2.3. Crystal structure of the W-type hexaferrite unit cell indicated by the arrow represents the local magnetic moment of the cation about the c-axis 28
Figure 2.4. Description of the M-H curve of magnetic materials 29
Figure 2.5. (a) Schematic diagram showing Hc behavior of magnetic particles depending on particle size of M-type hexaferrite...[이미지참조] 33
Figure 3.1. Outline diagram of solid-state reaction 38
Figure 3.2. Solid-state reaction process of M-type hexaferrites 40
Figure 3.3. Solid-state reaction process of W-type hexaferrites 42
Figure 4.1. XRD patterns of Ca₀.₁₅Sr₀.₅₅La₀.₃Fe₁₂₋₀.₃Co₀.₃O₁₉ samples sintered at 1100℃, 1150℃, 1200℃, 1230℃ 47
Figure 4.2. XRD patterns of Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at (a) 1100℃, (b) 1150℃, (c) 1200℃[이미지참조] 50
Figure 4.3. Enlarge view of XRD patterns in the range of 30 - 35 degrees of Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at (a) 1100℃, (b)...[이미지참조] 51
Figure 4.4. (a) Lattice parameters a and c of Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1100℃, 1150℃, 1200℃...[이미지참조] 53
Figure 4.5. SEM microstructures of the polished and chemical etched surfaces of x=0.0 sample sintered at (a) 1100℃, (b) 1150℃, (c) 1200℃... 55
Figure 4.6. SEM microstructures of polished and chemical etched surfaces of Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1100℃[이미지참조] 56
Figure 4.7. SEM microstructures of polished and chemical etched surfaces of Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1150℃[이미지참조] 57
Figure 4.8. SEM microstructures of polished and chemical etched surfaces of Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1200℃[이미지참조] 58
Figure 4.9. Average grain size of Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered at 1100℃, 1150℃ and 1200℃ observed by SEM images[이미지참조] 60
Figure 4.10. Hysteresis loop and initial magnetic curve of each sample sintered at (a) 1100℃, (b) 1500℃ and (c) 1200℃ 62
Figure 4.11. Law of approach to saturation (LAS) calculation: Calculate the values of A, R², and Hₐ according to calculation domain H to... 64
Figure 4.12. The influence of La-Co contents on coercivity (Hc) of 1100℃, 1150℃ and 1200℃ sintered samples[이미지참조] 69
Figure 4.13. (a) Saturated magnetization value (Mₛ) and (b) anisotropy field (Hₐ) as a function of x for Ca₀.₁₅Sr₀.₈₅₋ₓ(LaCo)ₓFe₁₁₋ₓO₁₉₋δ (0≤x≤0.4) samples sintered...[이미지참조] 70
Figure 4.14. XRD patterns of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)FeₙO₂₇ (n=15, 16) samples 72
Figure 4.15. XRD patterns of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn) with (a) full range of 20°~70° and (b) enlarge range of 30°~40° 75
Figure 4.16. Rietveld refinement of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn) composition 76
Figure 4.17. (a) Lattice parameters a and c of of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn) samples... 78
Figure 4.18. SEM images of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn) 80
Figure 4.19. Magnetic hysteresis loops with initial magnetization curves of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn) 82
Figure 4.20. Law of approach to saturation (LAS) calculation: (a) Calculate the values of A, R², and Hₐ according to calculation domain H.. 83
Figure 4.21. (a) Saturation magnetization value (Mₛ), (b) anisotropy field (Hₐ) and coercivity (Hc) of Sr(Fe₀.₅Zn₀.₅Ni₁.₀)Fe₁₄.₅M₀.₅O₂₇ (M=Fe, Al, Cr, Mn)[이미지참조] 87