Percolative BaTiO₃/Carbon-Nanotube Composite Films Employing Aerosol Deposition

Abstract

Percolative BaTiO3/multiwalled carbon nanotube (MWNT) composite thick films were developed using an aerosol deposition (AD) process at room temperature. Well-dispersed mixed powders with various volume ratios were utilized as the starting powders for AD, and dense BaTiO3/MWNT composite thick films were successfully fabricated with the starting mixed powders with 0.01 vol % MWNTs. The existence of MWNTs in the composite films was confirmed using Raman spectroscopy. The composite films show a high relative dielectric constant (657 at 1 kHz), which is approximately 7 times larger than that (91 at 1 kHz) of the BaTiO3 films. In addition, the strong frequency dispersion of the dielectric constant in the low-frequency range was confirmed for the composite films. The dielectric properties of the composite films were investigated using the dielectric mechanism used in percolative composites.

Effect of Zn filler for percolative BaTiO3/Zn composite films fabricated by aerosol deposition

“…In comparison with BaTiO 3 films, the dielectric constant of BaTiO 3 /Zn composite films indicate that it decrease as the frequency increases owing to dependence on the frequency. This is similar to results using other fillers, such as Cu, MWNTs, or PVDF [10][11][12][13]. This phenomenon can be explained by Maxwell-Wagner polarization.…”

“…In the case of 11.8 vol% Zn content, the dielectric constant increase above 200 at a frequency between 40 Hz and 1 MHz, and other samples are similar to pure BaTiO 3 at 1 MHz. Previously, BaTiO 3 was reported as having a low dependence on frequency [10][11][12]. In comparison with BaTiO 3 films, the dielectric constant of BaTiO 3 /Zn composite films indicate that it decrease as the frequency increases owing to dependence on the frequency.…”

“…This effect can be explained by the microcapacitor structure and space charge polarization. The microcapacitor can be formed in composite having spherical conductive filler [12]. Likewise, when the frequency increases, the dielectric loss shows a tendency to decrease.…”

“…In previously reported research, Maxwell-Wagner polarization exhibited Debye type a relaxation at low frequency of o 10 kHz, owing to strong dependence on frequency. The space charge or interfacial polarization that occurs into the composite films generates this phenomenon, and it occurs at the interface of grains and grain boundaries [11,12]. However, the dielectric constant is increase with high volume fraction of Zn.…”