Formation of a single quasicrystal upon collision of multiple grains

Quasicrystals exhibit long-range order but lack translational symmetry. When grown as single crystals, they possess distinctive and unusual properties owing to the absence of grain boundaries. Unfortunately, conventional methods such as bulk crystal growth or thin film deposition only allow us to synthesize either polycrystalline quasicrystals or quasicrystals that are at most a few centimeters in size. Here, we reveal through real-time and 3D imaging the formation of a single decagonal quasicrystal arising from a hard collision between multiple growing quasicrystals in an Al-Co-Ni liquid. Through corresponding molecular dynamics simulations, we examine the underlying kinetics of quasicrystal coalescence and investigate the effects of initial misorientation between the growing quasicrystalline grains on the formation of grain boundaries. At small misorientation, coalescence occurs following rigid rotation that is facilitated by phasons. Our joint experimental-computational discovery paves the way toward fabrication of single, large-scale quasicrystals for novel applications.

Zinc Gallium Oxide—A Review from Synthesis to Applications

Spinel ZnGa2O4 has received significant attention from researchers due to its wide bandgap and high chemical and thermal stability; hence, paving the way for it to have potential in various applications. This review focuses on its physical, optical, mechanical and electrical properties, contributing to the better understanding of this material. The recent trends for growth techniques and processing in the research and development of ZnGa2O4 from bulk crystal growth to thin films are discussed in detail for device performance. This material has excellent properties and is investigated widely in deep-ultraviolet photodetectors, gas sensors and phosphors. In this article, effects of substrate temperature, annealing temperature, oxygen partial pressure and zinc/gallium ratio are discussed for device processing and fabrication. In addition, research progress and future outlooks are also identified.

Materials purity, growth, and patterning

This chapter describes the purification and growth of organic materials, device patterning, and coating of large substrate areas using volume manufacturing processes. Organic semiconductors are no different from other electronic materials—purity is of the utmost importance. The chapter begins by describing several purification techniques for achieving and assessing the quality of electronic-grade materials. Next is a discussion of bulk crystal growth, and growth by more technologically important methods for achieving thin films using solution or vapor phase growth processes. Post-growth annealing for achieving desired film morphologies is also discussed. Patterning of device structures by photolithography, stamping and nanoimprint lithography on both planar and curved surfaces are described. This is followed by consideration of manufacturing processes such as roll-to-roll production, and the constraints that such processes place on the choice of substrate. Last, packaging and device encapsulation that maintain substrate flexibility while protecting devices from attack by adverse environments is discussed.