ELECTRICAL-CONDUCTIVITY AND THERMAL-EXPANSION OF BI2O3 DOPED WITH PR

Electrical conductivity and thermal expansion of Bi2O3 doped with 15 a nd 25 mol% prasoeodymia have been studied, named BP15 and BP25 respect ively. The crystal phases formed in the sintered oxides and their latt ice parameters were determined by X-ray diffraction (XRD). The electri cal conductivity was measured in air by means of both impedance spectr oscopy and the four-point DC technique within the temperature range 10 0-850-degrees-C. Thermal expansion coefficient measurements were carri ed out using the dilatometry technique. The results derived show the f ormation of a single rhombohedral phase in both cases which appears to be stable up to 680-degrees-C. The electrical conductivity is thermal ly activated exceeding 1.0 and 0.7 S/cm at 850-degrees-C for the compo sitions BP15 and BP25 respectively. The thermal expansion coefficient is highly non-linear and varies between 6 and 13 x 10(-6) K, presentin g an increase up to 500-degrees-C followed by a decrease above this te mperature region.