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Evidence of a Transition to Reorientational Disorder in the Cubic Alkali-metal Dodecahydro-closo-dodecaborates

Published

Author(s)

Kristina Verdal, Hui Wu, Terrence J. Udovic, Vitalie Stavila, Wei Zhou, John J. Rush

Abstract

A neutron powder diffraction (NPD) and differential scanning calorimetry(DSC) study indicates that Cs2B12H12 undergoes a second-order phase transition near 529 K that can be described as a reorientational disordering of the B12H22- icosahedral anions between two lowest-energy configurations within the cubic strucutre. Such a disordering requires the addition of another mirror plane to the low-temperature Fm3 structural symmetry to become Fm3{i}m. Additional DSC measurements of the lighter alkali-metal cubic isomorphs. Rb2B12H12 and K2B12H12, also indicate second-order transitions for these compounds near 742 K and 811 K, respectively. These results are suggestive of similar order-disorder phase changes as for Cs2B12H12, although confirmation of their existence requires analogous diffraction measurements.
Citation
Journal of Physics and Chemistry of Solids
Volume
184

Keywords

B12H12, dodecaborate, neutron powder diffraction, phase transition, reorientational disorder

Citation

, K. , Wu, H. , Udovic, T. , Stavila, V. , Zhou, W. and Kasianowicz, J. (2011), Evidence of a Transition to Reorientational Disorder in the Cubic Alkali-metal Dodecahydro-closo-dodecaborates, Journal of Physics and Chemistry of Solids, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=908798 (Accessed April 23, 2024)
Created November 1, 2011, Updated February 19, 2017