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.
Highlights
The quest for a better understanding of composition-structure-property relationships is one of the main focus in materials science research
The quantitative separation of chemical shifts (CS) and Knight shifts (KS) by Gauge-Including Projector Augmented-Wave (GIPAW) calculations is inherent to the method and each contribution is represented by two second-rank tensors named orbital and spin
Through a consistent combination of classical molecular dynamics (CMD) and Density Functional Theory (DFT) simulations, the experimental 27Al Solid-state nuclear magnetic resonance (ssNMR) metallic shifts of ZCA bulk metallic glasses (BMGs) were scrutinized in an unprecedented manner
Summary
The quest for a better understanding of composition-structure-property relationships is one of the main focus in materials science research. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy is a powerful technique that has been employed with a wide range of materials. Among them, those which can be obtained as amorphous solids with well-defined glass transition temperatures (Tg) are challenging. Recent works have reported investigations on the magnetic properties of certain glassy alloys[11] as well as some catalytic activity in electrochemical processes in the scope of energy storage and conversion[12] Another important point regarding research and design of BMGs is the limited set of experiments that can be resorted for characterization down to the atomic-scale. These are known as Knight shifts (KS) and, for some systems, find arguments to separate them from the competing CS without the aid of computational simulations may not be a simple task[19]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
