Journal Home > Volume 3 , Issue 1

Two sets of (Mg,Y)-doped BaTiO3 samples were prepared to investigate the effects of the core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO3: one set with samples of the same grain size but different core sizes and the other with samples of the same core size but different shell thicknesses. The microstructural variation of the samples was characterized and their dielectric properties were measured. For both sets of samples, the temperature stability of the dielectric properties was generally improved with a reduction of the volumetric shell ratio regardless of the grain and core sizes. There existed, however, a limit of the reduction; for the studied range, shell thickness of one third of the core radius appeared to be an optimum thickness for the given amounts of dopants. It was concluded that the volumetric shell ratio should be optimized so as not to exceed a specific limit, for our case two thirds of the grain volume, to secure temperature stability of the dielectric properties of BaTiO3.


menu
Abstract
Full text
Outline
About this article

Effects of core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO3

Show Author's information Sang-Chae JEONaByung-Kwon YOONbKwan-Hyeong KIMbSuk-Joong L. KANGa( )
Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu Daejeon 305-701, Korea
LCR Division, Samsung Electro-Mechanics, Suwon 443-743, Korea

Abstract

Two sets of (Mg,Y)-doped BaTiO3 samples were prepared to investigate the effects of the core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO3: one set with samples of the same grain size but different core sizes and the other with samples of the same core size but different shell thicknesses. The microstructural variation of the samples was characterized and their dielectric properties were measured. For both sets of samples, the temperature stability of the dielectric properties was generally improved with a reduction of the volumetric shell ratio regardless of the grain and core sizes. There existed, however, a limit of the reduction; for the studied range, shell thickness of one third of the core radius appeared to be an optimum thickness for the given amounts of dopants. It was concluded that the volumetric shell ratio should be optimized so as not to exceed a specific limit, for our case two thirds of the grain volume, to secure temperature stability of the dielectric properties of BaTiO3.

Keywords: dielectric properties, barium titanate, core/shell structure, temperature stability

References(29)

[1]
Kahn M. Effects of sintering and grain growth on the distribution of niobium addtion in barium titanate ceramics. Ph.D. thesis. University Park (USA): Pennsylvania State University, 1969.
[2]
Hennings D, Rosenstein G. Temperature-stable dielectrics based on chemically inhomogeneous BaTiO3. J Am Ceram Soc 1984, 67: 249–254.
[3]
Armstrong TR, Young KA, Buchanan RC. Dielectric properties of fluxed barium titanate ceramics with zirconia additions. J Am Ceram Soc 1990, 73: 700–706.
[4]
Lu H-Y, Bow J-S, Deng W-H. Core-shell structures in ZrO2-modified BaTiO3 ceramic. J Am Ceram Soc 1990, 73: 3562–3568.
[5]
Randall CA, Wang SF, Laubscher D, et al. Structure property relationships in core-shell BaTiO3–LiF ceramics. J Mater Res 1993, 8: 871–879.
[6]
Kim C-H, Park K-J, Yoon Y-J, et al. Formation of core-shell structure in BaTiO3 grains. J Korean Ceram Soc 2009, 46: 123–130.
[7]
Jeon S-C, Lee C-S, Kang S-JL. The mechanism of core/shell structure formation during sintering of BaTiO3-based ceramics. J Am Ceram Soc 2012, 95: 2435–2438.
[8]
Chazono H, Kishi H. Sintering characteristics in BaTiO3–Nb2O5–Co3O4 ternary system: I, Electrical properties and microstructure. J Am Ceram Soc 1999, 82: 2689–2697.
[9]
Chou C-C, Chen C-S, Lin I-N, et al. Development of X7R type base-metal-electroded BaTiO3 capacitor materials by co-doping of MgO/Y2O3 additives. Ferroelectrics 2006, 332: 35–39.
[10]
Tian Z, Wang X, Gong H, et al. Core-shell structure in nanocrystalline modified BaTiO3 dielectric ceramics prepared by different sintering methods. J Am Ceram Soc 2011, 94: 973–977.
[11]
Smolenskii GA. Physical phenomena in ferroelectrics with diffused phase transition. J Phys Soc Jpn 1970, 28: 26–37.
[12]
Cross LE. Relaxor ferroelectrics. Ferroelectrics 1987, 76: 241–267.
[13]
Kumar MM, Srinivas K, Suryanarayana SV. Relaxor behavior in BaTiO3. Appl Phys Lett 2000, 76: 1330.
[14]
Cui L, Hou Y-D, Wang S, et al. Relaxor behavior of (Ba,Bi)(Ti,Al)O3 ferroelectric ceramic. J Appl Phys 2010, 107: 054105.
[15]
Armstrong TR, Morgens LE, Maurice AK, et al. Effects of zirconia on microstructure and dielectric properties of barium titanate ceramics. J Am Ceram Soc 1989, 72: 605–611.
[16]
Chazono H, Fujimoto M. Sintering characteristics and formation mechanisms of "core-shell" structure in BaTiO3–Nb2O5–Co3O5 ternary system. Jpn J Appl Phys 1995, 34: 5354–5359.
[17]
Kishi H, Okino Y, Honda M, et al. The effect of MgO and rare-earth oxide on formation behavior of core-shell structure in BaTiO3. Jpn J Appl Phys 1997, 36: 5954–5957.
[18]
Kim J-S, Kang S-JL. Formation of core-shell structure in the BaTiO3–SrTiO3 system. J Am Ceram Soc 1999, 82: 1085–1088.
[19]
Kishi H, Kohzu N, Ozaki N, et al. Effect of occupational sites of rare-earth elements on the Curie point in BaTiO3. Proceedings of the 13th IEEE International Symposium on the Applications of Ferroelectrics 2002: 271–276.
[20]
Nishikawa J, Hagiwara T, Kobayashi K, et al. Effects of microstructure on the Curie temperature in BaTiO3–Ho2O3–MgO–SiO2 system. Jpn J Appl Phys 2007, 46: 6999–7004.
[21]
Kim CH, Park KJ, Yoon YJ, et al. Role of yttrium and magnesium in the formation of core-shell structure of BaTiO3 grains in MLCC. J Eur Ceram Soc 2008, 28: 1213–1219.
[22]
Park KJ, Kim CH, Yoon YJ, et al. Doping behaviors of dysprosium, yttrium and holmium in BaTiO3 ceramics. J Eur Ceram Soc 2009, 29: 1735–1741.
[23]
Kishi H, Kohzu N, Sugino J, et al. The effect of rare-earth (La, Sm, Dy, Ho and Er) and Mg on the microstructure in BaTiO3. J Eur Ceram Soc 1999, 19: 1043–1046.
[24]
Kishi H, Mizuno Y, Chazono H. Base-metal electrode-multilayer ceramic capacitors: Past, present and future perspectives. Jpn J Appl Phys 2003, 42: 1–15.
[25]
Yasukawa K, Nishimura M, Nishihata Y, et al. Core-shell structure analysis of BaTiO3 ceramics by synchrotron X-ray diffraction. J Am Ceram Soc 2007, 90: 1107–1111.
[26]
Wang T, Wang X, Wen H, et al. Effect of milling process on the core-shell structures and dielectric properties of fine-grained BaTiO3-based X7R ceramic materials. Int J Min Met Mater 2009, 16: 345–348.
[27]
McCauley DE, Chu MSH, Megherhi MH. PO2 dependence of the diffuse-phase transition in base metal capacitor dielectrics. J Am Ceram Soc 2006, 89: 193–201.
[28]
Yoon D-H. Tetragonality of barium titanate powder for a ceramic capacitor application. J Ceram Process Res 2006, 7: 343–354.
[29]
Jeon SC, Kang S-JL. Coherency strain enhanced dielectric-temperature property of rare-earth doped BaTiO3. Appl Phys Lett 2013, 102: 112915.
Publication history
Copyright
Acknowledgements
Rights and permissions

Publication history

Received: 14 January 2014
Accepted: 27 January 2014
Published: 05 March 2014
Issue date: March 2014

Copyright

© The author(s) 2014

Acknowledgements

This work was supported by the Samsung Electro- Mechanics Co. Ltd. through the Center for Advanced MLCC-Manufacturing Processes and also by the Priority Research Centers Program (Grant No. 2012- 048034) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST), Korea.

Rights and permissions

Open Access: This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.

Return