Charge density wave state in alpha-U: a multiple domain and single ->q structure.

Dark field imaging of charge density wave superlattice reflections in alpha-U by transmission electron microscopy reveals a multiple domain structure with a single wave vector q in each domain. It is found that the nearly commensurate charge density wave with q = (~0.5, 0, 0) occupies most of the areas (>~80%) at temperatures below 23K. The domains of the incommensurate charge density wave with q = (0.5,+-qy, +-q(z), which occupy the rest of the area, start to expand very rapidly as temperature approaches 23K. Thermal evolution of this phase transition is also studied. Striations similar to that observed in many martensitic transformations are also found at T