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

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.