In-situ conductivity and hydration studies of proton conductors using neutron powder diffraction

Journal article, 2012

An impedance spectroscopy cell and humidifier system has been developed to study the ion conducting properties and hydration/dehydration reactions in-situ during neutron powder diffraction experiments. As a model system, acceptor doped barium zirconate, BaZr0.5In0.5O2.75, has been studied during in-situ hydration and dehydration. Rietveld refinement of the collected data shows an increase in lattice parameter, a, upon hydration of BaZr0.5In0.5O2.75. In addition, we show the existence of a two-phase region, containing deuterated and non-deuterated barium zirconate, in the temperature interval ~ 573 K to ~ 873 K. Impedance spectroscopy data collected in-situ on heating and cooling and the corresponding ionic conductivity agree well with the change in deuteron content, as determined from neutron diffraction as a function of temperature. The newly developed in-situ cells make it possible to correlate conducting properties to structural changes under identical conditions and will have applicability to many other proton conducting solids.