Charge density redistribution with pressure in a zeolite framework

Abstract

As a result of external compression applied to crystals, ions relax, in addition to shortening the bond lengths, by changing their shape and volume. Modern mineralogy is founded on spherical atoms, i.e., the close packing of spheres, ionic or atomic radii, and Pauling and Goldschmidt rules. More advanced, quantum crystallography has led to detailed quantitative studies of electron density in minerals. Here we innovatively apply it to high-pressure studies up to 4.2 GPa of the mineral hsianghualite. With external pressure, electron density redistributes inside ions and among them. For most ions, their volume decreases; however, for silicon volume increases. With growing pressure, we observed the higher contraction of cations in bonding directions, but a slighter expansion towards nonbonding directions. It is possible to trace the spatial redistribution of the electron density in ions even at the level of hundredths parts of an electron per cubic angstrom. This opens a new perspective to experimentally characterise mineral processes in the Earth’s mantle. The use of diamond anvil cells with quantum crystallography offers more than interatomic distances and elastic properties of minerals. Interactions, energetic features, a branch so far reserved only to the first principle DFT calculations at ultra-high-pressures, become available experimentally.

Electron density changes accompanying high-pressure phase transition in AlOOH

“…The data set should be sufficiently complete to avoid systematic effects in the refinementideally 100% complete to a resolution higher that sinθ/λ = 1. Both accurate and precise measurements of the reflection intensities are needed to minimise systematic effects such as sample absorption, extinction and, very importantly, absorption by the apparatus itself, namely the diamonds and the metal gasket (Gajda et al, 2020(Gajda et al, , 2022Stachowicz et al, 2023). Furthermore, the contribution of valence electrons to the total reflection intensity never exceeds a few percent, which reinforces the need for very accurate intensity measurements.…”

Elastic and piezoelectric properties of β-glycine – a quantum crystallography view on intermolecular interactions and a high-pressure phase transition

“…Modeling of crystal structures under pressure by DFT methods has been performed for many compounds and functional materials: organic aromatic compounds such as syn-1,6:8,13-biscarbonyl[14]annulene (Casati et al, 2016(Casati et al, , 2017; perovskites (Tariq et al, 2015;Dar et al, 2017;Coduri et al, 2019;Ciupa-Litwa et al, 2020), kaolinites (Richard & Rendtorff, 2022;Richard & Rendtorff, 2022), carbonates (Zhuravlev & Atuchin, 2021;Zhuravlev & Korabel'nikov, 2022) and other inorganic compounds (Faridi et al, 2018;Nazir et al, 2018;Yaseen et al, 2021); grossular (Gajda et al, 2020), ice (Chodkiewicz et al, 2022), zeolites (Stachowicz et al, 2023) and also molecular crystals (Schatschneider et al, 2013;Liu et al, 2014;Moellmann & Grimme, 2014;Matveychuk et al, 2021). Such studies make it possible to predict mechanical, thermodynamic and optoelectronic properties, as well as phase transitions of various types.…”

“…This approach is known as quantum crystallography (Grabowsky et al, 2017;Tsirelson, 2018;Genoni & Macchi, 2020;Grabowsky et al, 2020;Tsirelson & Stash, 2020;Macchi, 2022;Matta et al, 2023). One of the important aims of quantum crystallography is to elucidate the mechanical characteristics of crystals, relating microscopic properties (distortions of chemical bonds, changes in the intermolecular contacts under high pressure) and macroscopic properties, such as structural response to hydrostatic pressure, compressibility and piezoelectric properties (Zhurova et al, 2006;Coudert & Fuchs, 2016;Riffet et al, 2017;Tsirelson et al, 2019;Evarestov & Kuzmin, 2020;Bartashevich et al, 2020;Korabel'nikov & Zhuravlev, 2020;Mishra & Tewari, 2020;Bartashevich et al, 2021;Feng et al, 2021;Matveychuk et al, 2021;Bogdanov et al, 2022;Gajda et al, 2022;Zhuravlev & Korabel'nikov, 2022;Stachowicz et al, 2023). Revealing relations between structural changes and mechanical properties of crystals helps to understand the nature of the piezoelectric effect and to design new piezoelectric materials (Guerin et al, 2019;Vijayakanth et al, 2022;Ivanov et al, 2023), as well as to rationalize thermo-and photomechanical effects with applications for design of materials and devices (Naumov et al, 2013(Naumov et al, , 2015Koshima et al, 2021;Karothu et al, 2022;Awad et al, 2023).…”

“…Orbital-free quantum crystallography approaches provide new opportunities to characterize crystals under compression (Zhurova et al, 2006;Casati et al, 2016Casati et al, , 2017Coudert & Fuchs, 2016;Tsirelson et al, 2016;Riffet et al, 2017;Tsirelson et al, 2019;Tsirelson & Stash, 2020;Evarestov & Kuzmin, 2020;Bartashevich et al, 2020;Korabel'nikov & Zhuravlev, 2020;Mishra & Tewari, 2020;Bartashevich et al, 2021;Gajda et al, 2022;Zhuravlev & Korabel'nikov, 2022;Stachowicz et al, 2023). As in the classical theory of elasticity (Landau et al, 2009), the compression and stretching of the electronic continuum in molecules and crystals can be described by the density of the stress tensor, (r) (Rogers & Rappe, 2002;Tao et al, 2008;Tsirelson et al, 2016).…”

Evolution of structure and spectroscopic properties of a new 1,3-diacetylpyrene polymorph with temperature and pressure

“…However, since the groundbreaking analysis of aromaticity at high pressure conducted by Casati et al (2016Casati et al ( , 2017, there have been few attempts at application of HAR or quantum crystallographic approaches in general in high-pressure structural analysis. These involved mostly inorganic highsymmetry systems, where challenges inherent to high-pressure structural analysis, such as moderate scattering power, imperfect absorption correction or poor data coverage, have been carefully circumnavigated (Gajda et al, 2020;Gun ´ka et al, 2021;Stachowicz et al, 2023;Chodkiewicz et al, 2022). Unsurprisingly, structure-property studies of organic materials under increased pressure rely predominantly on geometries obtained from theoretically predicted structures, sometimes without the ability to verify the adequacy of the theoretical model due to a lack of reliable high-pressure experimental geometry (Montisci et al, 2023).…”