A series of lead tungsten bronzes

The phases in samples of gross composition Pb_xWO₃ (0.01 ? x ? 0.28) heated at temperatures between 973 and 1373°K have been investigated. At all temperatures a nonstoichiometric tetragonal tungsten bronze phase forms for compositions x > 0.18. At temperatures up to 1273°K a series of orthorhombic intergrowth bronzes also forms, but these appear to be unstable at higher temperatures and were not found in the preparations made at 1373°K. Aspects of the crystal chemistry of these latter materials are discussed, including structure, crystal habit, valence of the Pb atoms in these phases, and the relation of the phases found here to other related intergrowth bronze phases.