Yttrium이 첨가된 BaTiO3에서 형성된 core/shell 구조에서 shell의 TCC 거동: 독립적 관찰
TCC behavior of a shell phase in core/shell structure formed in Y-doped BaTiO3:an individual observation
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초록
MLCC(Multi-Layer Ceramic Capacitor)의 유전체 층에 사용되는 BaTiO3 입자는 안정한 TCC(Temperature Characteristicsof Capacitance) 거동을 갖기 위해 core/shell 구조를 갖는다. 지금까지 shell의 특성은 core/shell 구조의 전체 특성에서 유추해 왔다. 이는 core/shell 구조가 겨우 수 μm의 작은 크기로 shell 특성만 구별해서 측정하기가 어렵기 때문이다. 본 실험에서는 micro-contact법을 이용하여 확산쌍 시편의 계면에 형성된 확대된 core/shell 구조에 Pt 전극을 증착하여 35~135°C 에서shell 영역의 독립적인 TCC 거동을 측정하였다. 그 결과, 65°C에서 최대 유전율 값을 갖는 완만한 피크의 확산 상전이(Diffusion Phase Transition) 거동인 core의 특성과 구별되는 거동을 관찰하였으며, 이는 core/shell 구조의 온도-유전거동을묘사하는 모델링에서 실험 자료로 활용될 것으로 본다.
Abstract
Grains in the BaTiO3, which is used for a dielectric layer in MLCC(Multi-Layer Ceramic Capacitor) are necessary to form core/shell structure for a stable TCC(Temperature Coefficient of Capacitance) behavior. The shell property has been deduced from the whole TCC behavior of core/shell structure due to its tiny size, ~ few μm. This study demonstrates the individual TCC behavior of the shell phase measured by micro-contact measurement in a temperature range between 35 and 135°C. Pt electrode pairs deposited on an enlarged core/shell structure in a diffusion couple sample made the measurement possible. As a result, the DPT (Diffusion Phase Transition) behavior of the shell phase was revealed as a different TCC behavior from that of the core: a broad peak with Tm at 65°C. This would be also useful experimental data for a modelling that depicts dielectric-temperature behavior of core/shell structure.
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