Several remarks on the medium-range order in glasses

An attempt has been made to find a unifying approach to various structural aspects of medium-range order (MRO) especially in connection with a scattering experiment. Examples of MRO as well as of the accompanying 'signatures' are discussed and simultaneously emphasis is given to the role of 'elements of MRO' in these considerations. The cluster concept of the amorphous structure is reviewed, generalised and accompanied by new Fraunhofer diffraction pictures and calculations of X-ray scattering for GeS(2). In this connection, large-scale modelling experiments are discussed and accompanied by results of 2D modelling experiments with deformable and incompressible particles. Finally, the concept of 'regular' and 'irregular' disorder is used to understand MRO-dependent scattering features. (C) 1998 Elsevier Science B.V. All rights reserved.