Phase Diagrams of Partially Ordered Materials

将对复杂的偏序材料的结构和热力学性质进行理论研究。两种类型的材料，准晶合金和磁流体，将由模型描述，这些模型捕捉最相关的能量和几何约束，同时保持足够简单，以执行准确的统计性质的分析计算。准晶是金属间化合物合金中一种常见但复杂的结构类型，似乎介于传统晶体和金属玻璃之间。利用几何瓦片模型作为真实原子位置的简略描述，研究了平衡结构之间的相图和相变作为相互作用、组成和温度的函数。磁流体是微小永磁体的胶体悬浮液。除了技术应用，这些材料还具有内在的科学价值，因为它们提供了偶极硬球流体的近似实现。这项工作将确定稀薄的各向同性气体和紧密堆积的磁性有序固体之间的相的性质。将对两种偏序复合材料的基本性质进行理论研究。准晶是十多年前在某些金属间合金中发现的，对于产生这种不寻常结构的机制仍然是一个谜。磁流体是一种应用广泛的人造磁性材料，无论是在基本原理上还是作为一种真实的材料体系，都是很有趣的。我们将使用统计物理和计算科学中的最新技术来研究这两种令人着迷的材料。

Theoretical research will be conducted on the structural and thermodynamic properties of complex, partially ordered materials. Two types of materials, quasicrystalline alloys and ferrofluids, will be described by models which capture the most relevant energetic and geometrical constraints, while remaining simple enough to perform accurate, analytic calculations of statistical properties. Quasicrystals, a common but complex structure type in intermetallic alloys, appear to be intermediate between conventional crystals and metallic glass. Employing geometrical tiling models as a shorthand description of real atomic positions, the phase diagram and phase transitions among equilibrium structures will be investigated as functions of interactions, composition and temperature. Ferrofluids are colloidal suspensions of microscopic permanent magnets. In addition to technological applications, these materials are of intrinsic scientific interest because they provide an approximate realization of a dipolar hard sphere fluid. This work will establish the nature of phases between the dilute isotropic gas and the close-packed magnetically ordered solid. %%% Theoretical research will be conducted on the basic properties of two partially ordered complex materials. Quasicrystals, which were discovered over a decade ago in certain intermetallic alloys, remain a mystery as to the mechanisms which produce this unusual structure. Ferrofluids, artificial magnetic materials with many applications, are interesting on a fundamental basis and as a real material system. Both of these fascinating materials will be studied using the latest techniques in statistical physics and computational science.