Abdelmjid Tairi

Phases stability and conduction properties in the Bi2O3-PbOPbF2 system

Abstract The Bi2O3-PbOPbF2 system was investigated by means of X-ray diffraction at temperatures between 770 and 950 K. Two solid solution domains have been evidenced. The first one exhibits a tetragonal cell (a = 7.74(1), c = 5.78(1) A for Bi(0.857)Pb(0.143)O(1.357)F(0.143)). Conductivity measurements performed by complex impedance method show that the value of σ remains lower than 10−7 (Ω.cm)−1 at 470 K. The second domain, isostructural with A La203 (hexagonal cell, a = 4.101(2), c = 6.087(2) A for Bi(0.5)Pb(0.5)0 F(0.5)) is more attractive: σ values close to 3×10 −4 (Ω.cm) −1 are reached at 470 K. The conductivity is strongly influenced by both oxygen and fluorine contents.

The Bi2WO6-TeO2 pseudo binary system

Summary The phase diagram of the Bi 2 WO 6 -TeO 2 pseudo-binary system has been established from 60 to 100 TeO 2 mol %, using DSC and XRD experiments. Three fixed temperature events were found: one eutectic and two peritectics. The new compounds Bi 2 Te 2 WO 10 and Bi 2 Te 5 WO 16 were identified and characterized by X-ray diffraction.