Rheology of nanocrystal-bearing technical and natural silicate melts

纳米级晶体（也称为纳米石）是火山熔体的重要组成部分。它们对岩浆粘度的影响尚未被理解，因为目前的流变参数化在模拟含纳米颗粒悬浮液的流变学时注定会失败。因此，该研究项目旨在通过研究玄武岩和流纹岩熔体的流变性作为纳米颗粒浓度、几何形状、表面性质和团聚程度的函数，获得潜在物理过程的基本知识。将使用最先进的分析工具的多方法方法来探索含纳米颗粒悬浮液在流变测量之前（和之后）的分子和介观结构。该项目将特别关注玻璃熔体中纳米石的形成，通过使用重复过冷差示扫描量热法探索液固转变早期阶段的动力学。结果将用于提供临界冷却速率的约束以及在过冷粘性熔体中形成纳米晶的条件。流变学和动力学数据的结合对于开展相关的数值模拟至关重要，以探索含纳米颗粒悬浮液的流体动力学含义，并提供对上升岩浆随时间变化的流变学的准确预测。

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.