Dielectric Relaxation and Electrical Conductivity in Bi5NbO10 Oxygen Ion Conductors Prepared by a Modified Sol-Gel Process

TL;DR

This study synthesizes Bi5NbO10 nanoparticles via a modified sol-gel process, characterizes their properties, and evaluates their potential as oxygen-ion conductors with promising ionic conductivity and dielectric behavior.

Contribution

It introduces a modified sol-gel synthesis method for Bi5NbO10 nanoparticles and investigates their dielectric and conductive properties, highlighting their potential for oxygen-ion conduction applications.

Findings

Nanoparticles of 5-60 nm were successfully prepared at 650°C.

Bi5NbO10 exhibits two dielectric relaxation mechanisms between 200-350°C.

Ionic conductivity at 700°C is comparable to Y2O3-stabilized ZrO2 ceramics.

Abstract

Crystalline Bi5NbO10 nanoparticles have been achieved through a modified sol-gel process using a mixture of ethylenediamine and ethanolamine as a solvent. The Bi5NbO10 nanoparticles were characterized by X-ray diffraction (XRD), differential scanning calorimetry/thermogravimetry, fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and Raman spectroscopy. The results showed that well-dispersed 5-60 nm Bi5NbO10 nanoparticles were prepared through heat-treating the precursor at 650C and the high density pellets were obtained at temperatures lower than those commonly employed. The frequency and temperature dependence of the dielectric constant and the electrical conductivity of the Bi5NbO10 solid solutions were investigated in the 0.1 Hz - 1 MHz frequency range. Two distinct relaxation mechanisms were observed in the plots of dielectric loss and the imaginary part of impedance versus frequency in the temperature range of 200-350oC. The dielectric constant and the loss in the low frequency regime were electrode dependent. The ionic conductivity of Bi5NbO10 solid solutions at 700oC is 2.86(ohm m)-1 which is in same order of magnitude for Y2O3-stabilized ZrO2 ceramics at same temperature. These results suggest that Bi5NbO10 is a promising material for an oxygen-ion conductor.