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Phase Relationship and Ionic Conductivity in Na–SrSiO 3 Ionic Conductor
Author(s) -
Jee Youngseok,
Zhao Xuan,
Lei Xueling,
Huang Kevin
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13925
Subject(s) - ionic conductivity , ionic bonding , amorphous solid , materials science , crystallite , phase (matter) , electrical resistivity and conductivity , doping , analytical chemistry (journal) , conductivity , conductor , ion , chemistry , crystallography , electrode , composite material , metallurgy , electrolyte , optoelectronics , organic chemistry , chromatography , electrical engineering , engineering
The Na–SrSiO 3 as a potential high‐conductivity ionic conductor for intermediate temperature solid oxide electrochemical cells (SOECs) has drawn much attention recently. Some of these studies questioned the feasibility of Na doping and therefore the creation of oxygen vacancies, while others suggested an alternative phase responsible for the ionic conduction. In this study, a systematic investigation was carried out to understand the ionic conduction in Na–SrSiO 3 . Through in situ high‐temperature X‐ray diffraction, thermal analysis, microstructural characterization, and electrical conductivity measurement, Na–SrSiO 3 was shown as a two‐phase material, one being slightly Na‐doped SrSiO 3 and another being amorphous Na 2 Si 2 O 5 . The former was an electrical insulator whereas the latter was a good ionic conductor. It was also found that the amorphous Na 2 Si 2 O 5 phase was unstable at the temperature ≥500°C, crystallizing into the insulating polycrystalline Na 2 Si 2 O 5 which causes conductivity to “bend‐over” at higher temperatures. A preliminary Ab Initio Molecular Dynamics ( AIMD ) simulation suggested that the amorphous Na 2 Si 2 O 5 be predominantly a Na + conductor.