High pressure synthesis of new plumbates of bismuth and thallium

Abstract

Oxides of the type A₂Pb₂O₇ (A = Tl, Bi) were prepared by solid state reaction at 700°C under 3 kbar pressure starting with Bi₂O₃, PbO₂, and Tl₂O₃ in sealed gold tubes. For red insulating Bi₂Pb₂O₇, a cubic (FCC) cell of 11.01Å accounts for the X-ray diffraction pattern. For black metallic Tl₂Pb₂O₇, a face centered rhombohedral cell with α=10.598Å and α = 89.55° accounts for the observed x-ray diffraction pattern. A solid solution of the type Tl_2-xBi_xPb₂O₇ was also prepared.