Solid state physics is the branch of physics that is primarily devoted to the study of matter in its solid phase, especially at the atomic level. This prestigious serial presents timely and state-of-the-art reviews pertaining to all aspects of solid state physics.

In the first article of this volume Thomson presents a comprehensive analysis of the long-standing problem of how solids fracture, with emphasis on the atomistic features of especial interest to physicists. Important questions dealt with include what determines mechanical toughness and whether the fracture will be brittle or ductile. It is shown that the answers to these questions require an understanding of the interactions between dislocations and cracks. These interactions are analyzed in detail.
"Age hardening" of alloys is due to the formation of clusters of impurity atoms during annealing. The structure of these clusters and its evolution during annealing has long been a central problem in physical metallurgy. The considerable progress made toward characterization and understanding of cluster structure and its evolution is reviewed and analyzed critically by J. B. Cohen in the second article of this volume. Special attention is given to the question of the distinctions between the earlier proposed stages of the clustering.
The third article deals with a major theoretical concept and mathematical technique that has found its way into condensed matter physics during the past few years. Fractals have become important in a wide variety of areas including percolation theory, polymer science, and the understanding of porous materials, rough surfaces, colloidal aggregates, dendritic growth, anomalous diffusion, and dilute magnetism.
The effects of 3d impurities in semiconductors have preoccupied the field since the invention of the transistor. Reliable experimental data for germanium and silicon became available quite early.