Markovian growth mechanism for a layered material as revealed by diffuse X-ray scattering

Diffuse X-ray scattering lines observed from the layered material Cu(C6H4(OH)COO)2.(H2O)2 (DSC) reveal a considerable degree of short-range stacking order, indicating direct correlation between the first few neighbouring layers. The data have been fitted to a 1D, two-parameter Markovian growth model, equivalent to a 1D Ising model involving nearest- and next-nearest-neighbour coupling. The disorder is caused by a combined effect of the one-dimensionality and the two coupling parameters, which are of the same sign. In the growth process the configuration of a given layer is influenced both by the previous layer configuration and the next previous one. Several samples from the same batch were studied, showing a considerable variation of the next-nearest-neighbour correlation parameters, indicating that the growth is very sensitive to the local external conditions (concentrations, impurities, temperature gradients, convection).