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Phase transitions and electrical conductivity of Bi‐doped La 2 Mo 2 O 9 oxide ion conductors
Author(s) -
Voronkova Valentina,
Kharitonova Elena,
Krasilnikova Alexandra
Publication year - 2009
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200925184
Subject(s) - differential scanning calorimetry , materials science , conductivity , bismuth , analytical chemistry (journal) , doping , arrhenius equation , phase transition , atmospheric temperature range , electrical resistivity and conductivity , phase (matter) , metastability , ceramic , oxide , activation energy , chemistry , thermodynamics , physics , organic chemistry , chromatography , electrical engineering , metallurgy , composite material , engineering , optoelectronics
La 2− x Bi x Mo 2 O y ( x = 0, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.1, 0.16, 0.24, 0.3) ceramic samples have been characterized by X‐ray diffraction, differential scanning calorimetry (DSC) and conductivity measurements in order to assess the dynamics of the transitions between the low‐temperature ( α ), high‐temperature ( β ) and metastable ( β ms ) phases. Bi doping to x ≥ 0.05 fully stabilizes the cubic phase, suppressing the β → α phase transition. In addition, DSC results demonstrate that considerable doping levels give rise to a small thermal event between 450 and 500 °C, which has been identified as the β ms → β phase transition between cubic phases with static and dynamic oxygen disorder. In this temperature range, the conductivity of the doped materials experiences a transition from Arrhenius to Vogel–Tammann–Fulcher behaviour. Low bismuth concentrations have a significant effect on the conductivity of La 2 Mo 2 O 9 .