Influence of ZnO addition and milling process on structure and conductivity of BaCe0.2Zr0.7Y0.1O3-δ ceramics

Abstract

Precursor powders for BaCe0.2Zr0.7Y0.1O3-δ(BCZY27) ceramics were synthesized by a modified Pechinimethod and calcined at 900°C for 12 h. The calcined BCZY27 powders were milled in eccentric and in high energy mill with the addition of 2 and 4mol% ZnO as sintering aid. The effects of milling and sintering aids on the sinterability and electrical conductivity were studied. The linear shrinkage in thermomechanical analyses started at 1050°C for the BCZY27 with 4mol% ZnO processed in eccentric mill. Theoretical density above of 90%TD was obtained for the BCZY27 milled with 4mol% ZnO and sintered at 1400°C for 4h. X-ray diffraction analysis of the BCZY27 ceramics sintered at 1400°C confirmed the presence of BaCe0.2Zr0.7Y0.1O3-δ and Y0.4Ce0.6O1.8 phases. The incorporation of Zn into perovskite lattice leads to the secondary phase formation. SEM and EDS analyses confirmed the presence of Y0.4Ce0.6O1.8 phase. The sintering was assisted by BaO-ZnO eutectic, which was reflected by the increase of activation energy values for grain boundary conduction. The milling processing did not affect the conductivity properties. The obtained BCZY27 dense sample has conductivity of 7.60 × 10−3 S/cm at 500°C.

Keywords

• perovskite
• wet-chemical synthesis
• electrical conductivity
• impedance spectroscopy
• fuel cells