Investigation of dielectric properties of amorphous, anatase, and rutile TiO₂ structures

Abstract

In this study, TiO₂ powder was prepared by sol-gel methods, divided into equal amounts, and three samples were formed. They, except for one sample, were annealed at different temperatures, and three bulk samples were obtained. The crystal structures of all samples were determined by X-ray diffraction (XRD) measurements. According to the XRD measurements, the first sample (T1) was an amorphous phase that did not undergo any heat treatment, the second sample (T2) annealed at 773 K was an anatase phase, and the last sample (T3) annealed at 1073 K was a rutile phase. Crystal parameters such as crystal sizes, dislocation density, and microstrain were determined by different methods such as the Scherrer, the Williamson-Hall, and the Halder-Wagner. The sizes of anatase and rutile crystal structures calculated based on the Scherrer equation of all samples were the smallest among all methods. These values were 21 and 54 nm for T2 and T3, respectively. Capacitance and conductance measurements of all samples were taken in the frequency range of 1 kHz to 1.5 MHz. Capacitance and conductance values of the sample, which was the amorphous crystal structure, were higher than other samples. The dielectric constant of the sample of rutile crystal structure might stay almost steady with changing frequency. Dielectric values of T1, T2, and T3 samples were 7.02 × 10³, 8.89 × 10¹, and 1.39 × 10² at 10 kHz, respectively. These values were 1.12 × 10³, 5.24 × 10¹, and 1.24 × 10² at 1 MHz for T1, T2, and T3, respectively.