Chemical stability study of BaCe0.9Nd0.1O3-α high-temperature proton-conducting ceramic

Abstract

BaCe _0.9 Nd _0.1 O _3-α (BCN) ceramic is known to be an excellent high-temperature proton conductor and is a candidate electrolyte for use in solid oxide fuel cells, hydrogen or steam sensors and steam electrolysers. In this work, the chemical stability of BCN was investigated systematically by combining XRD and DTA–TG techniques to study its processing compatibility and its feasibility in potential applications. It was found that above 1200 °C, BCN reacted with alumina or zirconia, leading to the loss of barium and an excess of cerium. In cold water, both sintered BCN disks and powder samples had very low solubility and did not hydrolyse, but they were soluble in some mineral acids, especially in HCl with the liberation of Cl ₂ . In boiling water, BCN pellets dissolved readily with decomposition into CeO ₂ and Ba(OH) ₂ . In 1 atm CO ₂ , BCN decomposed to form CeO ₂ and BaCO ₃ below 1200 °C during heating, but during cooling it was stable above 1000 °C, possibly because BCN has different crystal structures at low and high temperatures. At 600–1000 °C, BCN showed a slight mass loss when exposed to a reducing atmosphere, and a slight mass gain in an oxidizing atmosphere. XRD results revealed that BCN demonstrated chemical and structural stability in both reducing and oxidizing atmospheres.