Abstract
The hydrated oxygen deficient complex perovskite-related materials Sr 4(Sr 2Nb 2)O 11· nH 2O and Sr 4(Sr 2Ta 2)O 11· nH 2O were studied at high water vapour pressures over a large temperature range by electrical conductivity measurements, thermogravimetry (TG), and X-ray powder diffraction (XRPD). In humid atmospheres both materials are known to exhibit protonic conductivity below dehydration temperatures, with peak-shaped maxima at about 500 °C. In this work we show that the peaks expand to plateaus of high conductivity from 500 to 700 °C at a water vapour pressure of 1 atm. However, in situ synchrotron XRPD of Sr 4(Sr 2Nb 2)O 11· nH 2O as a function of temperature shows that these observations are in fact coincident with melting and dehydration of a secondary phase Sr(OH) 2. The stability of Sr 4(Sr 2Nb 2)O 11· nH 2O and Sr 4(Sr 2Ta 2)O 11· nH 2O in humid atmospheres is thus insufficient, causing decomposition into perovskites with lower Sr content and SrO/Sr(OH) 2 secondary phases. This, in turn, rationalizes the observation of peaks and plateaus in the conductivity of these materials.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
