Impedance Spectroscopy of Dielectric BaTi5O11 Film Prepared by Laser Chemical Vapor Deposition Method

1. Wuhan University of Technology, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, School of Materials Science and Engineering

2. Tohoku University, Institute for Materials Research

Correspondence to:
Dongyun Guo
Email: guodongyun@gmail.com

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Abstract

BaTi5O11 film was prepared on Pt/Ti/SiO2/Si substrate by the laser chemical vapor deposition method. A single-phase BaTi5O11 film with $$(\overline{3} 22)/(\overline{2} 23)$$ preferred orientation and columnar cross-section was obtained at high deposition rate (154.8 μm h−1). The dielectric constant (εr) of the BaTi5O11 film was 21, measured at 300 K and 1 MHz. The electrical properties of the BaTi5O11 film were investigated by ac impedance spectroscopy from 300 K to 1073 K at 102 Hz to 107 Hz. Plots of the real and imaginary parts of the impedance (Z′ and Z″) and electrical modulus (M′ and M″) in the above frequency and temperature range suggested the presence of two relaxation regimes, which were attributed to grain and grain boundary responses. The ac conductivity plots as a function of frequency showed three types of conduction process at elevated temperature. The frequency-independent plateau at low frequency was due to dc conductivity. The mid-frequency conductivity was due to grain boundaries, while the high-frequency conductivity was due to grains.

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• Accepted: Dec 16, 2011
• Online: Feb 23, 2012