Modelling the nature of disorder in talc by simulation of X-ray powder patterns

A sample of talc from Borgotaro (Parma, Italy) has been selected for its phase purity in order to investigate the nature of layer stacking disorder in talc. Earlier models describing disorder in talc have been fully revised using simulated powder patterns generated by DIFFaX. A new model has been suggested consisting of a random sequence of layers, stacked by a/3 along one of the pseudohexagonal X directions, affected by random planar disorder with components of +/-b/3. Modelling the planar disorder effects does not suffice alone to perfectly reproduce the experimental powder pattern, and other microstructure effects such as preferred orientation and size of the coherent crystallite domains must also be considered.