Université Paris-Saclay, CNRS, CEA, NIMBE, LIONS, CEA Saclay, 91191 Cedex Gif sur Yvette, France.
Published: July 2020
AI Article Synopsis
Article Abstract
Crystallization from solution is commonly described by classical nucleation theory, although this ignores that crystals often form via disordered nanostructures. As an alternative, the classical theory remains widely used in a "multistep" variant, where the intermediate nanostructures merely introduce additional thermodynamic parameters. However, this variant still requires validation by experiments addressing indeed proper time and spatial scales (millisecond, nanometer). Here, we used in situ X-ray scattering to determine the mechanism of magnetite crystallization and, in particular, how nucleation propagates at the nanometer scale within amorphous precursors. We find that the self-confinement by an amorphous precursor slows down crystal growth by 2 orders of magnitude once the crystal size reaches the amorphous particle size (∼3 nm). Thus, not only the thermodynamic properties of transient amorphous nanostructures but also their spatial distribution determine crystal nucleation.
A tubular strand of phosphorus composed of vectorially aligned pentagons has been theoretically predicted as a new allotrope of phosphorus with a polar structure, expecting potential applications. However, it has not been successfully synthesized yet due to the difficulty of creating isolated strands to avoid interchain bonding. Here, such an allotrope named "orange phosphorus" was successfully produced using a photo-assisted synthesis from an amorphous film of solution-processable Na2P16 precursors.
This work addresses the structural quantification of multiphase materials, here nanostructured polymer solid precursors and their micro/nano sized foamed counterparts. It is based on a strategy of contrast/edge enhancement, locally adaptive to image data in digital images of materials. The method allows to binarize straightforwardly the structures (the phases) in TEM and SEM images after edge identification, edge choice, and image virtual reconstruction.
- Nanoscale aluminosilicate minerals are used in various fields such as catalysis, environmental cleanup, and medicine.
- The study introduces a method called reactive laser ablation in liquid (RLAL) to create these nanominerals, where changing the pH and base used alters their characteristics.
- Different additives like ammonia and potassium hydroxide lead to distinct structures and compositions of the nanominerals, showcasing the versatility of RLAL for customizing materials for specific uses.
Laboratorio de Diseño y Optimización de Recubrimientos Avanzados (DORA-Lab), CIMAV-Mty/TECNL-CIIT, Parque de Investigación e Innovación Tecnológica, Apodaca, Nuevo León 66629, México.
Ongoing research in metal chalcogenide semiconductors aims to develop alternative materials for optoelectronic devices. However, due to cost and environmental considerations, there is an increasing emphasis on utilizing green materials. This shift toward sustainable materials and processing is expected to become essential in materials research.
Crystallization of amorphous precursors into metastable crystals plays a fundamental role in the formation of new matter, from geological to biological processes in nature to the synthesis and development of new materials in the laboratory. Reliably predicting the outcome of such a process would enable new research directions in these areas, but has remained beyond the reach of molecular modeling or ab initio methods. Here we show that candidates for the crystallization products of amorphous precursors can be predicted in many inorganic systems by sampling the local structural motifs at the atomistic level using universal deep learning interatomic potentials.
