Ceramic Quasicrystals

非技术描述：准晶体由规则大小和形状的构建块组成，可以填充空间，但没有可重复的图案。自古以来，数学家和艺术家就知道宏观准晶体，他们用这种图案制作马赛克。分子准晶体是非常罕见的。它们只存在于有限数量的合金和一些陨石中。这种不寻常的结构（平铺）使它们成为非常坚固材料的有希望的候选者，因为缺乏周期性可以防止裂纹的传播。今天建造的绝大多数承重结构都是由陶瓷材料制成的，但陶瓷准晶体还不为人所知。本项目旨在开发用纳米颗粒制备准晶陶瓷的通用方法，使其既简单又多样。这类陶瓷材料在国防、汽车、航空、电子等领域具有重要的应用价值。该项目包括对学生在尖端材料工程和计算机模拟技术方面的综合多方面培训。它还包括一个完整的推广和教育计划，以早期科学教育和准水晶瓷砖为中心，将科学和美学价值结合起来。技术细节：制备陶瓷准晶和复合准晶的关键将是陶瓷纳米颗粒自组织成准晶相。这种方法将使制造商避免极高的温度和压力。该项目选择的纳米颗粒是用聚合物修饰的球形SiO2。这种纳米颗粒具有两种相互竞争的远程相互作用，它们抑制传统相的结晶，有利于准晶体的形成。实验（Kotov）和模拟（Glotzer）的协同作用使得在温和条件下从SiO2中实验实现块状陶瓷准晶成为可能。最初在计算机上模拟的准晶相在水分散体中组装。在三维结晶成非周期结构之后，最初的软材料被退火成坚固的大块单体，通过强共价键相互连接。复合准晶体是通过单体渗透或逐层组装制备的。比较研究了不同准晶陶瓷的力学性能和裂纹扩展机制。它们有望揭示出其他任何材料都未曾发现的一系列特性。韧性、透明度和制备简单的结合可能会导致陶瓷及其应用的革命性变化。

NON-TECHNICAL DESCRIPTION: Quasicrystals are made from building blocks of regular size and shape that can fill up the space but do not have a repeatable pattern. Macroscale quasicrystals have been known since ancient times to mathematicians and artists who made are mosaics with such patterns. Molecular quasicrystals are very rare. They are found only for limited number of alloys and some meteorites. This unusual structure (tiling) makes them promising candidates for exceptionally strong materials because the lack of periodicity prevents the propagation of cracks. Vast majority of load-bearing structures built today are from ceramic materials but ceramic quasicrystals are not known. This project is aimed at developing general methods for preparation of quasicrystalline ceramics from nanoparticles that can make it both simple and diverse. Such ceramics materials may be of value for national defense, automotive industry, aviation, and electronics. The project includes an integrated multifaceted training of students in the cutting edge materials engineering and computer simulation technologies. It also includes an integral Outreach and Education Program, centered on early science education and quasicrystalline tilings which unite scientific and aesthetic values.TECHNICAL DETAILS: The key to the preparation of ceramic and composite quasicrystals will be self-organization of ceramic nanoparticles into quasicrystalline phases. This approach will allow the manufacturers to avoid extremely high temperatures and pressures. The nanoparticles selected for the project are spherical SiO2 modified with a polymer. Such nanoparticles feature two competing long-range interactions that inhibit crystallization in traditional phases in favor of quasicrystals. The synergy of experiment (Kotov) and simulations (Glotzer) make it possible to experimentally realize bulk ceramic quasicrystals from SiO2 under mild conditions. Quasicrystal phases simulated initially on the computer are assembled in aqueous dispersions. Following the three-dimensional crystallization into aperiodic structures, the initially soft materials are annealed to make robust bulk monoliths interconnected by strong covalent bonds. The composite quasicrystals are being made by monomer infiltration or layer-by-layer assembly. Different quasicrystalline ceramics are being comparatively investigated for mechanical properties and crack propagation mechanisms. They are expected to reveal set of properties previously unseen for any other materials. The combination of toughness, transparency and simplicity of preparation may lead to transformative changes in ceramics and their applications.