We report a joint experimental and theoretical study on high pressure structures of nanoporous mayenite (12CaO·7Al(2)O(3)). A pressure-induced amorphization was identified at ∼13 GPa by in situ high pressure x-ray experiments. The amorphous product can be decompressed to ambient conditions. Ab initio calculations reveal that the anisotropic deformations of empty cages break the crystallographic long-range orders, leading to the formation of high-pressure amorphous state. Furthermore, the deformation routes of empty cages are found fully dependent on their individual locally structural geometry relevant to the distribution of extra-framework oxygen ions.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1063/1.3631560 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Nonlinear Elasticity of Amorphous Silicon and Silica from Density Functional Theory.
J Phys Chem C Nanomater Interfaces
December 2024
Department of Chemistry, College of Staten Island, Staten Island, New York 10314, United States.
Density functional theory calculations and a finite deformation method are used to calculate second- and, most notably, third-order elastic constants of amorphous silicon and amorphous silicon dioxide, as represented by model structures generated via melt-quench force-field molecular dynamics simulations. Linear and nonlinear elastic constants are used to deduce macroscopic elastic moduli, such as the bulk and shear moduli, their pressure derivatives, and the elastic Grüneisen parameter. Our calculations show that the elastic properties of amorphous silicon reach the isotropic elastic limit within the nanometer length scale, attaining characteristics, both linear and nonlinear, comparable to those of crystalline silicon.
View Article and Find Full Text PDFNuclear quantum effects on glassy water under pressure: Vitrification and pressure-induced transformations.
J Chem Phys
December 2024
Department of Physics, Brooklyn College of the City University of New York, Brooklyn, New York 11210, USA.
We perform classical molecular dynamics (MD) and path-integral MD (PIMD) simulations of H2O and D2O using the q-TIP4P/F model over a wide range of temperatures and pressures to study the nuclear quantum effects (NQEs) on (i) the vitrification of liquid water upon isobaric cooling at different pressures and (ii) pressure-induced transformations at constant temperature between low-density amorphous and high-density amorphous ice (LDA and HDA) and hexagonal ice Ih and HDA. Upon isobaric cooling, classical and quantum H2O and D2O vitrify into a continuum of intermediate amorphous ices (IA), with densities in-between those of LDA and HDA (depending on pressure). Importantly, the density of the IA varies considerably if NQEs are included (similar conclusions hold for ice Ih at all pressures studied).
View Article and Find Full Text PDFImpact of route of particle engineering on dissolution performance of posaconazole.
Int J Pharm
December 2024
Pharmaceutical Materials Science and Engineering Laboratory, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, USA. Electronic address:
Article Synopsis
- - The study examines how different preparation methods (milling vs. precipitation) of micron-sized posaconazole crystals affect their pharmaceutical properties, particularly their dissolution performance.
- - To avoid issues from pressure-induced changes, researchers used powder dissolution instead of the typical method that compresses powders, but faced challenges due to the low wettability of the micronized powders.
- - By pre-treating the powders with a surfactant in an aqueous solution, the study showed that even with the formation of hydrates, the differing dissolution rates provide insight into how the methods of drug preparation affect their effectiveness in the body.
Pressure-induced phase changes in natural fluorapophyllite-(K) studied by Raman spectroscopy.
Spectrochim Acta A Mol Biomol Spectrosc
January 2025
Guangdong Provincial Key Laboratory of Mineral Physics and Materials, 510640, China.
The high-pressure Raman spectra in the low-wavenumber region (50-1200 cm) and the hydroxyl stretching vibration region (2600-3800 cm) of fluorapophyllite-(K) were collected in the interval of 0.0-50.7 GPa.
View Article and Find Full Text PDFReversible Giant Barocaloric Effect with Broad Working Temperature Range in an Amorphous Ethylene Propylene Diene Monomer.
J Phys Chem B
September 2024
Hangzhou Dianzi University, Hangzhou 310018, China.
The barocaloric effect of a solid material is an intense research topic due to its potential application in solid-state refrigeration. Among the proposed candidates, elastic polymers are distinctive because their barocaloric responses are independent from a pressure-induced phase transition which makes it possible to realize a broad working temperature range in principle. However, the barocaloric performance of most elastic polymers diminishes significantly as temperature decreases.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!