Yttrium-Doped Barium Zirconates as Ceramic Conductors in the Intermediate Temperature Range

Abstract

A modified Pechini process has been used to synthesize perovskite-structured yttrium-doped barium zirconate of the form BaZr0.85Y0.15O3-δ (BZY15). The X-ray diffraction pattern for the sintered material (5h at 1500°C) confirms a cubic structure with unit cell parameter of 8.424Å. Scanning electron microscopy images reveal a dense electrolyte structure. Thermal analysis (TGA/DTA) was also conducted on the material to determine possible endothermic and exothermic peaks and phase transformations. Raman spectroscopy data indicated that the most intense band in the spectrum of BZY15 occurs at 616cm−1, which suggests that cubic zirconia (Zr-O) vibrations are present. No bands were observed for secondary oxides, such as BaO, which would have a characteristic sharp band at 949cm−1, or Y2O3, whose characteristic band occurs at 376cm−1. AC-impedance measurements at 600°C indicate that the conductivity of the sample is higher in humidified gases compared to dry ones and has the lowest value in humidified air.