Pyrochlore Phases in the System ZnO–Bi 2 O 3 –Sb 2 O 5 : I. Stoichiometries and Phase Equilibria

Two cubic pyrochlore phases exist in the system ZnO–Bi 2 O 3 –Sb 2 O 5 . Neither has the supposed “ideal” stoichiometry, Zn 2 Bi 3 Sb 3 O 14 . One, P 1 , is a solid solution phase, Zn 2+ x Bi 2.96−( x − y ) Sb 3.04− y O 14.04+δ where 0< x <0.13(1), 0< y <0.017(2) and a =10.4285(9)−10.451(1) Å. The other, P 2 , is a line phase, Zn 2 Bi 3.08 Sb 2.92 O 13.92 with a =10.462(2) Å. Subsolidus phase relations at 950°C involving phases P 1 and P 2 in the ZnO–Bi 2 O 3 –Sb 2 O 5 phase diagram have been determined.