High-Throughput Screening of 3D-Printed Architected Materials Inspired by Crystal Lattices: Procedure, Challenges, and Mechanical Properties.

The search for load-bearing, impact-resistant, and energy-absorbing cellular materials is of central interest in many fields including aerospace, automotive, civil, sports, packaging, and biomedical. In order to achieve the desired characteristic geometry and/or topology, a perspective approach may be used, such as utilization of atomic models as input data for 3D printing of macroscopic objects. In this paper, we suggest a new approach for the development of advanced cellular materials-crystallomorphic design based on selection of perspective crystal structures and modeling of their electron density distribution and utilization of isoelectronic surfaces as a generatrix for 3D-printed cellular materials. The ATLAS database, containing more than 10 million existing and predicted zeolites, was used as a source of data. Herein, we introduced a high-throughput screening of a data array of crystalline compounds. Several perspective designs were identified, implemented by 3D printing, and showed high characteristics. A linear correlation was found between the strength of the samples and the minimum angle and minimum bond length in the simplified crystal structures. A new cellular geometry with reinforcement struts and increased strength was discovered. This property was found by us independent of the other works, in which the cellular structures were developed by an explicit method. Thus, the developed approach holds perspective for the design of new cellular structures with increased characteristics and for the prediction of their properties.

Control over the Surface Properties of Zinc Oxide Powders via Combining Mechanical, Electron Beam, and Thermal Processing.

The surface properties of zinc oxide powders prepared using mechanical activation, electron beam irradiation, and vacuum annealing, as well using combinations of these types of treatments, were studied using X-ray photoelectron spectroscopy. The structure of the obtained materials was studied by an X-ray diffraction technique and by scanning electron microscopy. We found that over five hours of grinding in an attritor, the size of nanocrystals decreases from 37 to 21 nm, and microdeformations increase from 0.3% to 0.6%. It was also found that a five-hour grinding treatment promoted formation of vacancies in the zinc sublattice at the surface and diffusion of Zn2+ cations into the bulk of the material. Irradiation of commercial zinc oxide powders with an electron beam with an energy of 0.9 MeV and a dose of 1 MGy induced breaking of Zn-O bonds, diffusion of interstitial zinc ions into the bulk, and oxygen atom escape from regular positions into the gas phase. A combined treatment of five hours of grinding and electron beam irradiation promoted accumulation of interstitial zinc ions at the surface of the material. Annealing of both initial and mechanically activated ZnO powders at temperatures up to 400 °C did not lead to a significant change in the properties of the samples. Upon exceeding the 400 °C annealing temperature the X-ray photoelectron spectra show almost identical atomic composition of the two types of materials, which is related to diffusion of interstitial zinc ions from the bulk of the material to the surface.