Incommensurately modulated Nowotny Chimney-ladder phases Cr1-xMoxGe similar to 1.75 with x=0.65 and 0.84

The crystal structures: of two new ternary, incommensurately modulated phas es in the Cr/Mo/Ge system, Cr1-xMoxGesimilar to1.75 with x = 0.65 and 0.84, have been refined using the same composite approach as for the earlier rep orted compounds. (Mo/Rh)(11)Ge-18 and (Mo/Rh)(13)Ge-22, from the Mo/Rh/Ge s ystem. The composite model consists of a rather stable diamond-like transit ion metal substructure and a helical main roup element arrangement. The sam e super space group pair, W: P4/nnc: q (1) over bar q1 P: I41/amd: 1 (1) ov er bar ss, the same positions and modulation waves were used. The refinemen ts of the new phases in the Cr/Mo/Ge system converged rapidly to R-values b elow 5% with GOF of 2.53 and 3.71, respectively. Each structure is built by two sub lattices with the parameters - alpha, c(x) and the modulation vect or q(x) - for Ge and alpha, c(T) and q(T) for the transition metals, The re fined data for x = 0.65 are found to he alpha = 5.935(2), c(x) = 2.770(1), c(T) = 4.839(1), q(X) = 0.428 [001]*, q(T) = 0.253 [001]* and for x = 0.84, alpha = 5.963(1), c(x),= 2.786(1), c(T) = 4.875(1), q(X) = 0.430 [001]*, q (T) = 0.264 [001]*, It is clearly shown the composite approach is applicabl e to different chimney-ladder compounds, even though they have quite differ ent compositions and hence q-vectors.