표제지
국문초록
목차
1. 서론 13
1.1. Multi-Layer Ceramic Capacitor 13
1.1.1. Multi-Layer Ceramic Capacitor의 수요 13
1.1.2. Multi-Layer Ceramic Capacitor의 연구 진행 방향 16
1.2. BaTiO₃ 17
1.2.1. BaTiO₃의 연구방향 17
1.2.2. 희토류 원소가 도핑된 BaTiO₃ 20
1.2.3. La 도핑된 BaTiO₃ 21
1.3. Positive temperature coefficient of resistivity (PTCR) 22
1.3.1. La 도핑된 BaTiO₃의 positive temperature coefficient of resistivity (PTCR) 22
1.4. Resistivity anomaly 24
1.4.1. La 도핑된 BaTiO₃의 resistivity anomaly 24
1.5. 연구목적 26
2. 실험 및 분석 27
3. 결과 및 토의 28
3.1. 결정구조 28
3.1.1. La 도핑 메커니즘 변화에 따른 BaTiO₃의 결정구조 변화 28
3.1.2. 온도에 따른 BaTiO₃의 결정구조 변화 30
3.1.3. Powder X-ray diffraction (PXRD) 32
3.1.4. XRD (101) peak 34
3.1.5. Powder X-ray diffraction (PXRD) Rietveld refinement 37
3.1.6. La 도핑 농도에 따른 격자상수 39
3.1.7. La도핑 농도에 따른 단위 셀 부피 41
3.1.8. X-ray photoelectron spectroscopy (XPS) - Ba 3d₂/₅[이미지참조] 44
3.1.9. X-ray photoelectron spectroscopy (XPS) - O 1s 47
3.2. 미세구조 49
3.2.1. La 도핑된 BaTiO₃의 상대밀도 49
3.2.2. Electron Backscattered Diffraction (EBSD) 52
3.2.3. Grain size 54
3.3. 전기적 특성 58
3.3.1. 온도 변화에 따른 La 도핑된 BaTiO₃의 비저항 58
3.3.2. La 도핑 농도에 따른 BaTiO₃의 비저항 61
3.3.3. La 도핑 농도에 따른 BaTiO₃의 AC 비저항 - 300K 65
3.3.4. La 도핑 농도에 따른 BaTiO₃의 AC 비저항- 423K 67
3.4. 유전 특성 69
3.4.1. 온도 변화에 따른 La 도핑된 BaTiO₃의 유전상수 69
3.4.2. La 도핑 농도에 따른 BaTiO₃의 유전상수 72
3.4.3. La 도핑 농도에 따른 BaTiO₃의 curie 온도 75
3.4.4. 주파수에 따른 La 도핑된 BaTiO₃의 유전상수 78
3.4.5. La 도핑 농도에 따른 BaTiO₃의 복소 임피던스 - 300K 80
3.4.6. La 도핑 농도에 따른 BaTiO₃의 복소 임피던스 - 423K 82
3.5. 열적 특성 84
3.5.1. La 도핑된 BaTiO₃의 La 도핑량과 온도에 따른 열전도도 84
4. 결론 86
참고문헌 89
Abstract 94
Table 1. (101) 2θ peaks of X-ray diffraction (XRD) θ for pristine and La-doped BaTiO₃ ceramics 36
Table 2. Relative density of La-doped BaTiO₃ for different doping concentrations 51
Figure 1. Structure of MLCC 15
Figure 2. ABX₃ perovskite structure 19
Figure 3. Charge compensation mechanism depending on La doping concentration in BaTiO₃ 29
Figure 4. Schematic illustration of the Temperature-dependent structure of BaTiO₃ 31
Figure 5. Powder X-ray diffraction (PXRD) pattern for pristine and La-doped BaTiO₃ ceramics 33
Figure 6. Zoomed-in (101) 2θ peaks of X-ray diffraction (XRD) for pristine and La-doped BaTiO₃ ceramics 35
Figure 7. Powder X-ray diffraction (PXRD) Rietveld refinement result for pristine and La-doped BaTiO₃ ceramics 38
Figure 8. Lattice parameters in a, b, and c-axes of La-doped BaTiO₃ 40
Figure 9. Lattice volume characterized by Rietveld refinement analysis for pristine and La-doped BaTiO₃ ceramics 43
Figure 10. X-ray photoelectron spectroscopy (XPS) for Ba 3d₂/₅[이미지참조] 46
Figure 11. X-ray photoelectron spectroscopy(XPS) for O 1s 48
Figure 12. Relative density of La-doped BaTiO₃ for different doping concentrations 50
Figure 13. Electron backscatter diffraction(EBSD) image quality(IQ) maps and inverse pole figure(IPF) maps of pristine, 0.1 mol% La, 0.2... 53
Figure 14. The average grain sizes and the standard deviations of the of pristine, 0.1 mol% La, 0.2 mol% La, and 0.4 mol% La-doped BaTiO₃ samples 56
Figure 15. average grain size of pristine, 0.1 mol% La, 0.2 mol% La, and 0.4 mol% La-doped BaTiO₃ samples 57
Figure 16. Temperature-dependent resistivities of La-doped BaTiO₃ for different doping concentrations 60
Figure 17. La doping concentration dependent resistivities of La-doped BaTiO₃ 63
Figure 18. La doping concentration dependent resistivities of La-doped BaTiO₃ in blue data, yellow[41], green 64
Figure 19. AC resistivities of La-doped BaTiO₃ samples (0.1 to 0.4 mol%) at 300 K 66
Figure 20. AC resistivities of La-doped BaTiO₃ samples (0.1 to 0.4 mol%) at 423 K 68
Figure 21. Temperature-dependent dielectric constant of La-doped BaTiO₃ for different doping concentrations 71
Figure 22. La doping concentration dependent dielectric constant of La-doped BaTiO₃ 74
Figure 23. La doping concentration dependent curie temperature of La-doped BaTiO₃ 77
Figure 24. Frequency dependent dielectric constant of La-doped BaTiO₃ for different doping concentrations 79
Figure 25. Complex impedance measurements of La-doped BaTiO₃ samples (0.1 to 0.4 mol%) at 300 K 81
Figure 26. Complex impedance measurements of La-doped BaTiO₃ samples (0.1 to 0.4 mol%) at 423 K 83
Figure 27. Thermal conductivity of La-doped BaTiO₃. 85
Figure 28. Influence of charge compensation mechanism in La-doped BaTiO₃ ceramics on the structural, electrical, dielectric and thermal properties 88