The wulfenite-stolzite series: centric or acentric structures?

摘要

Three natural crystals of the wulfenite (PbMoO₄)–stolzite (PbWO₄) series were investigated by single-crystal X-ray diffraction. The results indicate that the symmetry is I4₁/a from nearly pure wulfenite to intermediate compositions, in contrast to previous work which claimed a symmetry change to I symmetry (acentric) for intermediate compositions compared with I4₁/a (centric space group) for the end-members. The results reported here show that the reflections violating I4₁/a symmetry observed in this work and in a previous study are related primarily to /2 effects, even if Renninger effects are not excluded. Consequently, we find that the I4₁/a symmetry is retained throughout the wulfenite– stolzite series.