Effects of core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO<sub>3</sub>

doi:10.1007/s40145-014-0096-y

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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.

Key words： barium titanate core/shell structure dielectric properties temperature stability

Received: 14 January 2014 Published: 12 June 2015

Corresponding Authors: Suk-Joong L. KANG

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	Sang-Chae JEON
	Byung-Kwon YOON
	Kwan-Hyeong KIM
	Suk-Joong L. KANG

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Sang-Chae JEON,Byung-Kwon YOON,Kwan-Hyeong KIM, et al. Effects of core/shell volumetric ratio on the dielectric-temperature behavior of BaTiO₃[J]. Journal of Advanced Ceramics, 2014, 3(1): 76-82.

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http://jac.tsinghuajournals.com/EN/10.1007/s40145-014-0096-y OR http://jac.tsinghuajournals.com/EN/Y2014/V3/I1/76

Schematic illustrations showing the core/ shell structures (a) in the first set with different core sizes and a similar grain size and (b) in the second set with a similar core size but different shell thicknesses.

SEM micrographs of (a) 0.6BT, (b) 0.3BT and (c) 0.1BT in the first set. The numbers in the micrographs are the measured average grain sizes.

TEM micrographs and TEM/EDS line scanning results of grains in 0.3BT sample ((a) and (c), respectively) and 0.1BT sample ((b) and (d), respectively).

(a) Measured dielectric properties and (b) TCC curves of the first set for a temperature range of -55–150 ℃.

TEM/EDS result showing the Y concentration in the shell of a grain. The scale bar for each data point represents the standard deviation of five measurements.

SEM micrographs of (a) BT-0.5, (b) BT-1 and (c) BT-4 in the second set. (d) Measured core volumetric percentage and core size with respect to sintering time. The numbers in micrographs are the measured average grain sizes.

(a) Measured dielectric properties and (b) TCC curves of the second set for a temperature range of -55–150 ℃.

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