Low-temperature fabrication of titanium metal/barium titanate composite capacitors via hydrothermal method and their dielectric properties

Abstract

We attempted to fabricate metal/dielectrics composite capacitors exhibiting high effective dielectric constant by a lowtemperature wet chemical approach. The green compacts consisting of Ti metal particles, BaTiO 3 fillers, and TiO 2 precursor nanoparticles were successfully converted into Ti/BaTiO 3 composite compacts by the hydrothermal method at 160°C. The effective dielectric constant of these composites tends to increase with the Ti metal content and jumped up to over 10 3 near the percolation threshold. When we used the Ti(core)BaTiO 3 (shell) particles as the metal component, the thin BaTiO 3 shell layers covering on the Ti particles prevented the direct contact among metal particles and increases the percolation threshold. Since the effective dielectric constant of these composites depends largely on the dielectric properties of the BaTiO 3 layers, it is important to control the microstructure of these composites to improve the dielectric properties of such composites.

Electrical Properties of Ti/BaTiO₃ Composite Capacitors with Nanostructured Core-Shell Particles

“…However, the Eb seems to be independent of the thickness of the BT shell layers of the core-shell particles. In Table II, there is a trade-off relationship between the effective dielectric constant and the Eb which corresponds to the relationships previously reported for the Ti/BT composites [8,9]. The effective dielectric constant and the Eb of the metal/insulator Table II The effective dielectric constant, <ε>, and tangent loss of the Ti/BT composites recorded at 100 kHz and their dielectric breakdown strength.…”

“…We have previously reported the low-temperature fabrication of the Ti/BaTiO3 (BT) composite materials with embedded Ti metal particles in the BT layer by the hydrothermal method [8,9]. The effective dielectric constant of the Ti/BT composite capacitors increases with the Ti metal content up to around 8000, and such dielectric constant behavior can be explained by the percolation theory [10,11].…”

“…Moreover, for the case of using low-melting-point metals, an unexpected drastic change of microstructures of metal/insulator composite materials is possible to be caused by grain growth, melting, or evaporation of metals and to lead to deteriorate electrical properties of the composites [5][6][7]. Thus, low-temperature fabrication processes of such composite materials are required.We have previously reported the low-temperature fabrication of the Ti/BaTiO3 (BT) composite materials with embedded Ti metal particles in the BT layer by the hydrothermal method [8,9]. The effective dielectric constant of the Ti/BT composite capacitors increases with the Ti metal content up to around 8000, and such dielectric constant behavior can be explained by the percolation theory [10,11].…”

Recent Progress in Applications of the Cold Sintering Process for Ceramic–Polymer Composites

“…A lot of efforts have been made to reduce the sintering temperatures of ceramics; some of those are inspired from the natural densification of geological and biological mineralization activities, in which a liquid phase, usually an aqueous solution, is involved in order to increase the driving force of densification. Representative examples include hydrothermal sintering, modified low‐temperature hydrothermal sintering, reactive hydrothermal liquid‐phase densification, room temperature fabrication of Li 2 MoO 4 ceramic, and cold sintering process, among which cold sintering is a low‐temperature sintering technology that has been recently developed. It has been demonstrated that many ceramics can be readily densified under low‐temperature conditions (temperature = 25–300 °C) with the assistance of a transient liquid phase .…”

Preparation of BaTiO₃ Nano-structured Ceramics by Solvothermal Solidification Method

“…We have studied on the low-temperature preparation process of dense ceramics by utilizing solution reactions. There are some additional advantages for the low-temperature process; it is capable of a preparation of composite ceramics with low thermostable materials such as base metals [1], and a preparation of composite materials without a formation of solid-solution [2][3][4].…”