Investigation of the high temperature structural behavior of La0.99Ca0.01NbO4 proton conducting material

In this paper we report a preliminary neutron diffraction investigation of the proton conducting La0.99Ca0.01NbO4 material. Measurements have been acquired from room temperature up to 750 °C under dry and wet atmosphere. The main result of this investigation is the observation of the existence of a broad temperature interval where the low-T monoclinic phase coexists with the high-T tetragonal phase. Even at the highest investigated temperature small fractions of the monoclinic phase have been detected under the experimental conditions employed here.