Crystal structure and charge carrier behaviour of (W_12.64Mo_1.36)O₄₁ and its significance to other related compounds

The crystal structure of (W_12.64Mo_1.36)O₄₁, containing {102} crystallographic shear (CS) planes, has been solved, a = 23.939 (9), b = 3.966 (1), c = 16.729 (15) Å, β = 106.74 (5)°; P2/c; R = 0.10 for 1285 reflections. It was shown that the Mo atoms segregate on positions in the CS planes. The O atom octahedra are distorted in typical arrangements, so that the elastic strain energy could be estimated. The hypothetical phases (W,Mo)_nO_{3n - 1} for a wide range of values of n were derived from the experimental atomic parameters. Optical and electrical experiments show the existence of two types of charge carriers, a minority in the interplanar material, which contribute to conductivity, and a majority of trapped positions in the CS planes, preferentially on Mo positions.