Synthesis and electrical conductivity of Y1-xMn1-yO3-delta

YMnO3-related materials [stoichiometric (Y/Mn = 1), and Y or Mn deficient] were synthesized by a traditional ceramic route. Dense pellets obtained aft er sintering at different temperatures (1400-1500 degreesC) were characteri zed by XRD, SEM/EDS, dilatometry (up to 1270 degreesC) and dc electrical co nductivity measurements in air (between 200 and 1000 degreesC). The electri cal conductivities of all compositions were close to each other and within the range 10(-4) S/cm at about 200 degreesC to 1 S/cm at about 1000 degrees C. Arrhenius plots show three different slopes with smooth transitions arou nd 300-350 degreesC and 600-650 degreesC. The activation energy increases f rom about 50 kJ/mol below 300 degreesC to about 90 kJ/mol between 650 and 1 000 degreesC. XRD, SEM/EDS and thermal expansion measurements provided enou gh evidence on phase and mechanical stability constraints, thus questioning potential technological applications. (C) 2001 Elsevier Science Ltd. All r ights reserved.