Burns research focuses on the solid state and environmental chemistry of heavy metals, especially actinides including uranium, neptunium and plutonium. Studies of natural crystals coupled with synthetic approaches are being used to develop the structural hierarchical relationships in actinide compounds. Aggregation of metals in solution, and subsequent crystallization of molecular clusters, is examined using conventional crystallographic techniques coupled with synchrotron X-ray scattering. Current emphasis includes studies of the structures and stabilities of uranium, thorium and plutonium clusters containing as many as 120 metal atoms. Much of this research is applied to nuclear waste disposal and understanding the mobility of actinides and heavy metals in the environment. The structures, compositions, stabilities, and thermochemistry of uranium compounds is studied in relation to the evolution of a geological repository for nuclear waste, as well as natural uranium deposits.