Dy 및 Mg가 첨가된 BaTiO₃에서 소결 온도가 미세구조와 유전특성에 미치는 영향
Effect of sintering temperature on microstructure and dielectric properties in (Dy, Mg)-doped BaTiO₃
2
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
MLCC(Multi-Layer Ceramic Capacitor)의 유전체 층에 사용되는 BaTiO₃는 유전 특성의 온도안정성을 향상시키기 위해 첨가제로서 희토류 및 Mg를 사용한다. 이러한 첨가제는 소결 중 입자성장 및 치밀화 거동, 결국 유전 특성에 지대한영향을 주게 되므로 조성에 따른 미세구조 발현 양상을 살펴보는 것이 중요하다. 본 연구는 95BaTiO₃-1Dy₂O₃-2MgO-2SiO₂ (mol%)의 조성에서 온도 변화에 따른 결정구조, 입자성장 및 밀도 변화를 관찰하고 이러한 변화가 유전 상수에 미치는 영향을 관찰하였다. 1200~1300°C의 온도범위에서 소결 온도가 증가함에 따라, 평균 입도는 눈에 띄게 커지는 반면 밀도의 변화는 미미하여 입자크기가 주요한 미세구조적 요소임을 밝혔다. 본 실험에서 관찰된 입자크기의 온도의존성은 기존 입자성장 이론에서 설명한 온도 변화에 따른 입자성장 거동의 변화양상과 잘 부합하였으며, 이러한 이해는 향후 희토류가 첨가된 BaTiO₃에서 유전 특성 향상을 위한 소결 미세구조 제어에 유용하게 활용될 수 있을 것이다.
Abstract
Rare-earth elements were doped with Mg to enhance the temperature stability of dielectric properties of BaTiO₃ for its application to MLCC (Multi-Layer Ceramic Capacitor). The additives strongly affect both grain growth and densification behaviors during sintering, and hence dielectric properties. The additive effects therefore should be examined in each system with different additives. This study investigated the crystal structure, grain growth and densificationbehaviors and related variations in dielectric constant with respect to sintering temperature. Dielectric constant appears to be varied with grain size in a temperature range between 1200 and 1300°C, suggesting the importance of grain size control. The temperature dependence of grain size variation was well explained by an established theory correlating the grain growth behavior with grain boundary structure. This accordance provides a basis for sintering technique to control grain growth thus to improve dielectric constant in rare-earth doped BaTiO₃.
참고문헌 (30)
- T. Nagai, "Effect of MgO Doping on the phase transformations of BaTiO3", J. Am. Ceram. Soc, 83(1), pp.107~ (2000)
- C. Randall, "History of the first ferroelectric oxide, BaTiO3", pp.1~ (2004), Materials Research Institute, The Pennsylvania State University, University Park
- 노태민, "Dysprosium과 Erbium이 동시 첨가된 X7R MLCC용 페로브스카이트 BaTiO_3의 전기적특성과 온도안정성", 한국세라믹학회지, 48(4), pp.323~327 (2011), 한국세라믹학회
- 전상채, "Yttrium이 첨가된 BaTiO3에서 형성된 core", shell 구조에서 shell의 TCC 거동: 독립적 관찰, 2020, pp.30(3), 110~116[DOI]
- 박형규, "稀土類金屬 製鍊技術 개요", 자원리싸이클링, 21(3), pp.74~83 (2012), 한국자원리싸이클링학회[DOI]
- M. Kahn, "Effects of sintering and grain growth on the distribution of niobium addition in barium titanate ceramics", Ph.D, pp.1969
- B.S. Rawal, "Grain Boundary Phenomena in Electronic Ceramics", pp.172~178 (1981), American Ceramic Society
- D. Hennings, "Temperature-stable dielectrics based on chemically inhomogeneous BaTiO3", J. Am. Ceram. Soc, 67, pp.249~ (1984)
- H.Y. Lu, "Core-shell structures in ZrO2-modified BaTiO3 ceramic", J. Am. Ceram. Soc, 73, pp.3562~ (1990)
- H. Chazono, "Sintering characteristics and formation mechanisms of ‘Core-Shell’ structure in BaTiO3-Nb2O5-Co3O5 ternary system", Jpn. J. Appl. Phys, 34, pp.5354~ (1995)
- S.C. Jeon, "The mechanism of core", shell structure formation during sintering of BaTiO3-based ceramics, 2012, pp.95, 2435~
- F.D. Morrison, "Charge compensation mechanisms in La-doped BaTiO3", J. Electroceram, 6, pp.219~ (2001)
- F.D. Morrison, "An alternative explanation for the origin of the resistivity anomaly in La-doped BaTiO3", J. Am. Ceram. Soc, 84, pp.474~ (2001)
- J.I. Itoh, "Oxygen defects related to electrical properties of La-doped BaTiO3", Jpn. J. Appl. Phys, 41, pp.3798~ (2002)
- V. Paunović, "Influence of rare-earth additives (La, Sm and Dy) on the microstructure and dielectric properties of doped BaTiO3 ceramics", Sci. Sintering, 42, pp.69~ (2010)
- 박금진, "BaTiO₃ 세라믹 내 희토류(Dy, Y, Ho) 첨가 효과", 한국세라믹학회지, 46(2), pp.181~188 (2009), 한국세라믹학회
- S.C. Jeon, "Effect of core", shell volumetric ratio on dielectric-temperature behavior in (Mg, Y)-doped BaTiO3, 2014, pp.3, 76~
- S.C. Jeon, "Oxidation-induced strain relaxation and related dielectric-temperature behavior in core", shell grained BaTiO3, 2015, pp.35, 129~
- S.C. Jeon, "Coherency strain enhanced dielectric-temperature property of rare-earth doped BaTiO3", Appl. Phys. Lett, 102, pp.112915~ (2013)
- C.H. Kim, "Role of yttrium and magnesium in the formation of core-shell structure of BaTiO3 grains in MLCC", J. Eur. Ceram. Soc, 28, pp.1213~ (2008)
- C.S. Chen, "TEM microstructures of X7R type base-metal electrode BaTiO3 capacitor materials co-doped with MgO", Y2O3 additives, 2006, pp.332, 41~
- S.C. Jeon, "Interface structure dependent step free energy and grain growth behavior of core", shell grains in (Y, Mg)-doped BaTiO3 containing a liquid phase, 2022, pp.42, 2804~
- R.D. Shannon, "Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides", Acta Cryst, A32, pp.751~ (1976)
- S.D. Cho, "Study on the effects of BaTiO3 particle size on dielectric constant and leakage current of epoxy", BaTiO3 composite films for embedded capacitors, 2002, pp.9(2), 11~
- P. Zheng, "Grainsize effects on dielectric and piezoelectric properties of poled BaTiO3 ceramics", Acta Mater, 60, pp.5022~ (2018)
- S.J.L. Kang, "Sintering: densification, grain growth and microstructure" (2004), Elsevier
- Y.I. Jung, "Coarsening of polyhedral grains in a liquid matrix", J. Mater. Res, 24, pp.2949~ (2009)
- Y.H. Heo, "Effect of step free energy on delayed abnormal grain growth in a liquid phase-sintered BaTiO3 model system", J. Eur. Ceram. Soc, 31, pp.755~ (2011)
- K.S. Moon, "Effect of TiO2 addition on grain shape and grain coarsening behavior in 95Na1", 2Bi1, J. Eur. Ceram. Soc, pp.2011, 31[DOI]
- S.M. An, "Boundary structural transition and grain growth behavior in BaTiO3 with Nd2O3 doping and oxygen partial pressure change", Acta Mater, 59, pp.1964~ (2011)