“…Examples include ternary oxide systems of Bi-Dy-W [7], Bi-Er-W [8], Bi-Ln-Te (Ln = La, Sm, Gd, Er) [9], Bi-Y-Nb [10] and Bi-Ln-V (Ln = La-Yb) [11]. PbO has also been used as a "co-stabiliser" in the Bi 2 O 3 -CaO-PbO and Bi 2 O 3 -Y 2 O 3 -PbO systems [12,13]. In both systems an extensive fluorite-type solid solution was found, the materials were highly conductive, and ionic transfer numbers between 500 and 800°C were close to unity.…”