Rheology of nanocrystal-bearing technical and natural silicate melts

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Nano-sized crystals (also called nanolites) are emerging key components of volcanic melts. Their effect on the magma viscosity has not yet been understood as current rheological parameterisations are bound to fail in modelling the rheology of nanoparticle-containing suspensions. The research project aims therefore in gaining basic knowledge of the underlying physical processes by studying the rheology of basaltic and rhyolitic melts as a function of concentration, geometry, surface property and degree of agglomeration of nanoparticles. A multi-method approach of state-of-the-art analytic tools will be used to explore the molecular and mesoscopic structure of nanoparticle-containing suspensions before (and after) the rheometric measurements. The project will pay particular attention to the formation of nanolites in the glass melts by exploring the kinetics of the early stage of the liquid-to-solid transformation using inter alia repetitive supercooling differential scanning calorimetry. Results will be used to provide constraints on the critical cooling rate and the conditions under which nanolites will form in the undercooled viscous melt. The combination of rheometric and kinetic data will be essential to carry out relevant numerical simulations to explore the implications for the fluid dynamics of nanoparticle-bearing suspensions and to offer accurate predictions of the time-dependent rheology of a rising magma.