Structural relationships in the series AxP4O8(WO3)2m (A = K,Rb): A high-resolution electron microscopy study

The first members of the series A_xP₄O₈(WO₃)_2m were studied by means of electron microscopy. These bronzes can be classified into two groups on the basis of ReO₃-type block composition: even- and odd-m members. High-resolution lattice images of tungstophosphate crystals (m ≤ 10) allow us to establish a correlation between the image contrast and the framework of the structure. The structural mechanism proposed for this series is discussed and compared to the possibility of intergrowth, and to the crystallographic shear phenomena observed in tungsten and molybden oxides.