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Altering the Structural Properties of A2B12H12 Compounds via Cation and Anion Modifications

Published

Author(s)

Wan Si NMN Tang, Terrence J. Udovic, Vitalie Stavila

Abstract

The recent discovery of unusually high cationic conductivity in Na2B12H12 above its entropy-driven, order-disorder phase transition near 529 K and the expected similar conductivity behavior in Li2B12H12 above its transition near 615 K have lead us to investigate modifications of these two materials in an effort to reduce their transition temperatures and thus extend their high conductivities to more technological favorable values. Differential scanning calorimetry measurements perhalogenated Na2B12X12 (X=Cl and I), which are larger anion relatives of Na2B12H12, suggest unfavorably higher transition temperature near 730 K and 816 K, respectively. New mixed-cation LiyNa2-yB12H12 phases show intermediate transition temperatures between those of Li2B12H12 and Na2B12H12. X-ray diffraction measurements and neutron vibrational spectra corroborate similar low-temperature ordered structures as pure Li2B12H12 (for y=0.67, 1, and 1.33) with Li+ and Na+ disordered among the near-trigonal cation sites.
Citation
Journal of Alloys and Compounds
Volume
645

Keywords

Borohydrides, order-disorder phase transition, superionic conductivity, ionic modification, perhalogenated dodecaborate, dodecahydro-closo-dodecaborate

Citation

NMN, W. , Udovic, T. and Stavila, V. (2015), Altering the Structural Properties of A<sub>2</sub>B<sub>12</sub>H<sub>12</sub> Compounds via Cation and Anion Modifications, Journal of Alloys and Compounds, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917141 (Accessed February 27, 2024)
Created October 5, 2015, Updated February 19, 2017