Preparation of titanium metal/barium titanate composites with boundary layer structure by hydrothermal method and their dielectric properties

To develop metal/insulator composite capacitors with a high effective dielectric constant, we focus on the microstructure of boundary layer (BL) capacitors. Titanium metal/barium titanate (Ti/BT) composites consisting of Ti metal grains and BT boundary nanolayers were successfully prepared from pres...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 2015-10, Vol.54 (10S), p.10
Main Authors: Ueno, Shintaro, Sakamoto, Yasunao, Kakiuchi, Hiroyuki, Nakashima, Kouichi, Wada, Satoshi
Format: Article
Language:English
Subjects:
Barium titanates
Boundary layer
Capacitors
Core-shell particles
Dielectric constant
Dissolution
Nanostructure
Titanium
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Summary:To develop metal/insulator composite capacitors with a high effective dielectric constant, we focus on the microstructure of boundary layer (BL) capacitors. Titanium metal/barium titanate (Ti/BT) composites consisting of Ti metal grains and BT boundary nanolayers were successfully prepared from pressed Ti-BT core-shell particle compacts by a hydrothermal method below 230 °C. In this hydrothermal method, BT polycrystalline shell layers connected to each other by crystal growth via a dissolution and reprecipitation mechanism in barium hydroxide [Ba(OH)2] aqueous solutions. The thickness of BT boundary layers may increase with an increase in the Ba(OH)2 concentration and determine electrical properties. These Ti/BT composites prepared in 250 and 500 mmol/dm3 Ba(OH)2 solutions exhibit effective dielectric constants of over 5000 and 3000, and loss tangents below 0.075 and 0.060 in the frequency range of 100 Hz-100 kHz at room temperature, respectively.
ISSN:0021-4922
1347-4065
DOI:10.7567/JJAP.54.10NB07