Orientational order/disorder and network flexibility in deuterated methylammonium lead iodide perovskite by neutron total scattering
Journal of Materials Chemistry A Royal Society of Chemistry (RSC) (2024)
Siliceous zeolite-derived topology of amorphous silica.
Communications chemistry 6:1 (2023) 269
Abstract:
The topology of amorphous materials can be affected by mechanical forces during compression or milling, which can induce material densification. Here, we show that densified amorphous silica (SiO2) fabricated by cold compression of siliceous zeolite (SZ) is permanently densified, unlike densified glassy SiO2 (GS) fabricated by cold compression although the X-ray diffraction data and density of the former are identical to those of the latter. Moreover, the topology of the densified amorphous SiO2 fabricated from SZ retains that of crystalline SZ, whereas the densified GS relaxes to pristine GS after thermal annealing. These results indicate that it is possible to design new functional amorphous materials by tuning the topology of the initial zeolitic crystalline phases.Superstructure and Correlated Na+ Hopping in a Layered Mg-Substituted Sodium Manganate Battery Cathode are Driven by Local Electroneutrality.
Chemistry of materials : a publication of the American Chemical Society 35:24 (2023) 10564-10583
Abstract:
In this work, we present a variable-temperature 23Na NMR and variable-temperature and variable-frequency electron paramagnetic resonance (EPR) analysis of the local structure of a layered P2 Na-ion battery cathode material, Na0.67[Mg0.28Mn0.72]O2 (NMMO). For the first time, we elucidate the superstructure in this material by using synchrotron X-ray diffraction and total neutron scattering and show that this superstructure is consistent with NMR and EPR spectra. To complement our experimental data, we carry out ab initio calculations of the quadrupolar and hyperfine 23Na NMR shifts, the Na+ ion hopping energy barriers, and the EPR g-tensors. We also describe an in-house simulation script for modeling the effects of ionic mobility on variable-temperature NMR spectra and use our simulations to interpret the experimental spectra, available upon request. We find long-zigzag-type Na ordering with two different types of Na sites, one with high mobility and the other with low mobility, and reconcile the tendency toward Na+/vacancy ordering to the preservation of local electroneutrality. The combined magnetic resonance methodology for studying local paramagnetic environments from the perspective of electron and nuclear spins will be useful for examining the local structures of materials for devices.Local structure and lithium-ion diffusion pathway of cubic Li 7 La 3 Zr 2 O 12 studied by total scattering and the Reverse Monte Carlo method
Journal of Materials Chemistry A Royal Society of Chemistry (RSC) 11:46 (2023) 25516-25533
Structural insights into hybrid immiscible blends of metal-organic framework and sodium ultraphosphate glasses.
Chemical science 14:42 (2023) 11737-11748