Enhanced polarization and dielectricity in BaTiO3:NiO nanocomposite films modulated by the microstructure

Abstract

Parallel and vertical interfaces in vertically and parallelly aligned nanocomposite thin films have been shown to be an effective method to manipulate functionalities. However, tuning the physical properties by modulating the microstructure of the self-assembled nanocomposite films and understanding the physical properties underlying the manipulation is still a challenge. In this work, BaTiO₃:NiO (BTO:NiO) nanocomposite films with nanomultilayer, nanocolumnar and nanogranular structures have been prepared on Nb:SrTiO₃ (Nb:STO) substrates by a pulsed laser deposition (PLD) method. These films have been used as a model system to investigate the relationship between the microstructure and the ferroelectric properties. The polarization, dielectricity and leakage can be separately modulated by tuning the microstructures. The experimental results show that the remanent polarization of the nanocomposite films is much higher than that of the pure BTO films. By precisely modulating the microstructure, a significantly enhanced polarization (>70% higher than pure BTO for the nanomultilayer structure) and dielectricity (>60% and >240% higher than pure BTO for the nanomultilayer and nanocolumnar structure, respectively) are realized in these films. These results demonstrate that tunable ferroelectric properties can be realized by controlling the microstructures in the epitaxial BTO:NiO nanocomposite thin films, which will be expected to be applied in the devices such as supercapacitors, solar cells and non-volatile memory applications.