J. H. Song

The microstructure, energy storage and dielectric behaviours of (Ti,Zn)-doped Bi0.97Nd0.03FeO3 thin films

Abstract (Ti, Zn)-co-doped Bi0.97Nd0.03FeO3 (BNFTZ) thin films with different thicknesses were prepared directly on indium tin oxide/glass substrates deriving from the precursor solutions with different solution concentrations. The X-ray diffraction, scanning electron microscopy and insulating/ferroelectric/dielectric measurements were utilised to characterise the BNFTZ thin films. Both BNFTZ thin films with the thicknesses of 160 and 320 nm are crystallised into phase-pure perovskite structure without second phase. Compared to the film of 160 nm, a lower leakage current can be obtained in BNFTZ film of 320 nm due to due to its denser microstructure with smaller grain size. The film with 320 nm thickness possesses a high energy-storage efficiency of 87%, which can be ascribed to the slim P–E loop. At 100 kHz, the film of 320 nm owns lower dielectric constant (~91) and dissipation factor (~0.10). The possible contributions are discussed to explain the difference in the related performances for BNFTZ thin films with different thicknesses.

Microstructure, leakage current and dielectric tunability properties of W6+:Na0.5Bi0.5TiO3/Fe3+:Na0.5Bi0.5TiO3 bilayered thin film

Abstract The bilayered Na0.5Bi0.5Ti0.99W0.01O3/Na0.5Bi0.5Ti0.98Fe0.02O3 (NBTW/NBTFe) structure was grown on indium tin oxide/glass using a modified sol–gel process. The microstructure, and insulating and dielectric properties were investigated. X-ray diffraction indicates that the bilayered thin film is well crystallized with a phase-pure perovskite structure. The thin film shows a uniform surface without crack, and no interface is found between the NBTW/NBTFe structure. In the dielectric constant-electric field curves for dielectric measurement, abnormal loops are observed under the low electric field or high frequency. A maximum value of 35.4% for dielectric tunability is obtained when an electric field of ±500 kV/cm is applied, which can be mainly due to the good insulating characteristic with low leakage current. Furthermore, a dielectric constant of 484, dielectric loss of 0.07 as well as figure of merit of 5.1 can be observed at the frequency of 100 kHz. These findings can be taken as a base for further improving the electrical performance of NBT-based thin films.