On the use of atomistic simulations to aid bulk metallic glasses structural elucidation with solid-state NMR

Abstract

Solid-state nuclear magnetic resonance (ssNMR) experimental 27Al metallic shifts reported in the literature for bulk metallic glasses (BMGs) were revisited in the light of state-of-the-art atomistic simulations. In a consistent way, the Gauge-Including Projector Augmented-Wave (GIPAW) method was applied in conjunction with classical molecular dynamics (CMD). A series of Zr-Cu-Al alloys with low Al concentrations were selected as case study systems, for which realistic CMD derived structural models were used for a short- and medium-range order mining. That initial procedure allowed the detection of trends describing changes on the microstructure of the material upon Al alloying, which in turn were used to guide GIPAW calculations with a set of abstract systems in the context of ssNMR. With essential precision and accuracy, the ab initio simulations also yielded valuable trends from the electronic structure point of view, which enabled an overview of the bonding nature of Al-centered clusters as well as its influence on the experimental ssNMR outcomes. The approach described in this work might promote the use of ssNMR spectroscopy in research on glassy metals. Moreover, the results presented demonstrate the possibility to expand the applications of this technique, with deeper insight into nuclear interactions and less speculative assignments.

13C NMR Parameters of Disordered Carbons: Atomistic Simulations, DFT Calculations, and Experimental Results

“…Moreover, the components of the NMR chemical shielding tensor can be obtained from atomistic models and confronted directly with experimental data; consequently, measurements and calculations of the components of the chemical shielding tensor are of high interest both for crystalline and disordered materials. [8][9][10] Especially, the use of NMR to probe the local bonding structure can be an adequate complement to di↵raction techniques (e.g, X-ray, electron or neutron di↵raction), which are more suited to probe the average local environments or the medium to long range order in the material.…”

“…Among the important properties of carbon materials, the nuclear magnetic resonance (NMR) chemical shielding is particularly useful due its sensitivity to the local chemical environment around the probe nuclei. Moreover, the components of the NMR chemical shielding tensor can be obtained from atomistic models and confronted directly with experimental data; consequently, measurements and calculations of the components of the chemical shielding tensor are of high interest for both crystalline and disordered materials. − Especially, the use of NMR to probe the local bonding structure can be an adequate complement to diffraction techniques (e.g, X-ray, electron or neutron diffraction), which are more suited to probe the average local environments or the medium- to long-range order in the material. Recent theoretical reports have used first-principles calculations based on the density functional theory (DFT) to establish correlations between the shielding tensor and structural features of carbon nanotubes, graphite oxide, graphene, and graphitic materials. , …”