To date, the formation mechanisms of TiO, as well as its heterostructures, have not been clarified. Moreover, detailed research on the transition from a tetragonal anatase phase to the monoclinic phase of the TiO(B) phase and their interface structure has been quite limited until now. In the present study, we report on the sonochemical synthesis of TiO-anatase with a crystallite size of 5.2 ± 1.5 nm under different NaOH concentrations via the hydrothermal method. The use of alkaline solution and the effect of the temperature and reaction time on the formation and structural properties of TiO-anatase nanopowders were studied. The effects of NaOH concentration on the formation and transformation of titanate structures are subject to thermal effects that stem from the redistribution of energy in the system. These mechanisms could be attributed to three phenomena: (1) the self-assembly of nanofibers and nanosheets, (2) the Ostwald ripening process, and (3) the self-development of hollow TiO mesostructures.
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http://dx.doi.org/10.3390/ma13030685 | DOI Listing |
Phys Chem Chem Phys
January 2025
Institut de Recherche sur les Céramiques (IRCER), UMR CNRS 7315-Université de Limoges, France.
A semi-automated workflow relying on atomic-scale modelling is introduced to explore and understand the yet-unsolved structure of the crystalline AsTe material, recently obtained from crystallization of the parent AsTe glass, which shows promising properties for thermoelectric applications. The seemingly complex crystal structure of AsTe is investigated with density functional theory, from the stand point of As/Te disorder, in a structural template derived from elemental-Te (Te), following experimental findings from combined X-ray total scattering and diffraction. Our workflow includes a combinatorial structure generation step followed by successive structure selection and relaxation steps with progressively-increasing accuracy levels and a multi-criterion evaluation procedure.
View Article and Find Full Text PDFSci Rep
January 2025
College of Mechanical Engineering, Zhejiang University of Technology, No.18, Chaowang Road, Hangzhou, 310014, Zhejiang Province, China.
To observe the chemical mechanical polishing (CMP) process at the atomic scale, reactive force field molecular dynamics (ReaxFF-MD) was employed to simulate the polishing of 6 H-SiC under three conditions: dry, pure water, and HO solution. This study examined the reactants on the surface of 6 H-SiC during the reaction in the HO solution, along with the dissociation and adsorption processes of HO and water molecules. The mechanisms for atom removal during the CMP process were elucidated.
View Article and Find Full Text PDFSci Adv
January 2025
Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996, USA.
Metastable phases can exist within local minima in the potential energy landscape when they are kinetically "trapped" by various processing routes, such as thermal treatment, grain size reduction, chemical doping, interfacial stress, or irradiation. Despite the importance of metastable materials for many technological applications, little is known about the underlying structural mechanisms of the stabilization process and atomic-scale nature of the resulting defective metastable phase. Investigating ion-irradiated and nanocrystalline zirconia with neutron total scattering experiments, we show that metastable tetragonal ZrO consists of an underlying structure of ferroelastic, orthorhombic nanoscale domains stabilized by a network of domain walls.
View Article and Find Full Text PDFInt J Heat Mass Transf
March 2024
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095, United States of America.
In classical theory, heat conduction in solids is regarded as a diffusion process driven by a temperature gradient, whereas fluid transport is understood as convection process involving the bulk motion of the liquid or gas. In the framework of theory, which is directly built upon quantum mechanics without relying on measured parameters or phenomenological models, we observed and investigated the fluid-like convective transport of energy carriers in solid heat conduction. Thermal transport, carried by phonons, is simulated in graphite by solving the Boltzmann transport equation using a Monte Carlo algorithm.
View Article and Find Full Text PDFSmall
December 2024
Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069, Dresden, Germany.
The chemical engineering of nanostructures with atomic-scale precision is a fundamental scientific challenge. Cation exchange reactions in nanoplatelets (NPLs) offer an attractive platform for this precision chemistry, as it is relatively simple to carry out, extremely versatile, and allows the production of heterogeneous nanostructures that cannot be produced by any other means. A major hindrance has, however, been the lack of knowledge of the "weak spots" of the platelets where the ionic exchange reaction is initiated to optimally control the process toward directed nanoscale assemblies.
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