Composition-structure-property relationship in tectosilicate solid solutions synthesized from glass

尽管在硅酸盐材料和玻璃结晶领域投入了大量的研究工作，但知识差距仍然存在，阻碍了对玻璃陶瓷技术中可能有利的材料系统的充分理解和详细评估。在这个项目中，我们的目标是通过基本的组成-结构-性质调查来填补这些漏洞，集中在三种特定的构造硅酸盐，即方石英，石英和白榴石的固溶体，由于其技术相关性，其开发潜力和实验欠确定性而被选中。该目的是通过利用玻璃作为起始材料的非平衡、动力学冻结状态来实现的，因为它允许在受控的再加热时探索化学亚稳结晶相，否则不可能合成。因此，该方法遵循Ostwald的阶段规则，首先获得最不稳定的多晶型物（固溶体）。在玻璃形成方面，实验的目标是通过用溶胶-凝胶喷雾干燥路线扩大熔融淬火来制备尽可能广泛的相关化学成分和浓度。一方面，工作组已建立了适当的仪器玻璃制备和结构表征过程中的结晶。通过它，通过在环境温度下以及在高温和低温下进行原位测量（主要是XRD），将深入了解所需固溶体晶体及其结构的演变。另一方面，该项目旨在充分了解所制备的固溶体晶体的晶体学约束，包括对已知晶体多晶型物的明确分配或分歧以及它们的转变行为。在玻璃陶瓷技术方面，目标是通过详细评估相关性能（如热膨胀），了解可能有利的系统和这些阶段的发展潜力。

Despite the intensive research efforts that have been invested in the fields of silicate materials and glass crystallization, knowledge gaps still persist and prevent full understanding and detailed assessment of possibly advantageous materials systems in glass-ceramic technology. With this project, we aim at closing those loopholes through a fundamental composition-structure-property investigation, concentrating on three specific tectosilicates, i.e. solid-solutions of cristobalite, quartz and leucite that have been selected due to their technological relevance, their development potential and their experimental underdetermination. The objective is to be achieved by taking advantage of the non-equilibrium, kinetically frozen-in state of glass as a starting material, since it allows upon controlled reheating to explore thermodynamically metastable crystalline phases otherwise impossible to synthesize. Thereby the approach follows the Ostwald's rule of stages in accessing the least stable polymorph (solid solution) first. In terms of glass formation, experiments are targeted to prepare the widest possible range of relevant chemical components and concentrations by expanding melt-quenching with the sol-gel spray-drying route. On the one hand, the working group has established appropriate instrumentation for glass preparation and structural characterization during crystallization. Through it, insights will be gained into the evolution of desired solid solution crystals and their structure by performing measurements at ambient, as well as in-situ at high and cryogenic temperatures (mainly XRD). On the other hand, the project aims at fully understanding the crystallographic constraints of the prepared solid solution crystals including a clear assignment or divergence to known crystal polymorphs as well as their transformation behavior. In terms of the glass-ceramic technology, the objective is to gain knowledge on possibly advantageous systems and the development potential of these phases by a detailed assessment of relevant properties, such as thermal expansion.