Mechanosynthesis of nanopowders of the proton-conducting electrolyte material Ba(Zr, Y)O 3−δ

Abstract

The formation of perovskite nanopowders of the common proton-conducting, electrolyte material Ba(Zr 1− x Y x )O 3− δ is demonstrated by room temperature mechanosynthesis for the compositional range x=0, 0.058 and 0.148. This is achieved with a planetary ball mill at 650 rpm in zirconia vials, starting from BaO 2 with ZrO 2, (ZrO 2) 0.97(Y 2O 3) 0.03 or (ZrO 2) 0.92(Y 2O 3) 0.08 precursors, respectively. Powder X-ray diffraction (XRD) reveals the formation of the perovskite phase in the early stages of milling with phase purity being achieved after milling times of 240 min for composition x=0.058 whereas 420 min is necessary for composition x=0.148. In contrast, traces of ZrO 2 are apparent in composition x=0 even after milling times of 420 min. The use of BaCO 3 as precursor does not allow the formation of the perovskite phase for any composition. The perovskite crystallites are spherical in shape with an average size determined from XRD of ca. 30 nm in agreement with transmission electron microscopy observations. FTIR spectra demonstrate that contamination levels of BaCO 3 in the mechanosynthesized powders are very low. The spherical shape and nanoscale of the crystallites allow densification levels that are highly competitive when compared to BaZrO 3-based materials formed by alternative synthesis techniques documented in the literature.