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Interplay between the reorientational dynamics of the B3H8–anion and the structure in KB3H8

DOI: 10.1021/acs.jpcc.0c10186 DOI Help

Authors: M. S. Andersson (Chalmers University of Technology; National Institute of Standards and Technology) , J. B. Grinderslev (Aarhus University) , X.-M. Chen (Henan Normal University) , X. Chen (Henan Normal University; Zhengzhou University) , U. Haussermann (Stockholm University) , W. Zhou (National Institute of Standards and Technology,) , T. Jensen (Aarhus University) , M. Karlsson (Chalmers University of Technology) , T. J. Udovic (National Institute of Standards and Technology; University of Maryland)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C

State: Published (Approved)
Published: February 2021

Open Access Open Access

Abstract: The structure and reorientational dynamics of KB3H8 were studied by using quasielastic and inelastic neutron scattering, Raman spectroscopy, first-principles calculations, differential scanning calorimetry, and in situ synchrotron radiation powder X-ray diffraction. The results reveal the existence of a previously unknown polymorph in between the α′- and β-polymorphs. Furthermore, it was found that the [B3H8]− anion undergoes different reorientational motions in the three polymorphs α, α′, and β. In α-KB3H8, the [B3H8]− anion performs 3-fold rotations in the plane created by the three boron atoms, which changes to a 2-fold rotation around the C2 symmetry axis of the [B3H8]− anion upon transitioning to α′-KB3H8. After transitioning to β-KB3H8, the [B3H8]− anion performs 4-fold rotations in the plane created by the three boron atoms, which indicates that the local structure of β-KB3H8 deviates from the global cubic NaCl-type structure. The results also indicate that the high reorientational mobility of the [B3H8]− anion facilitates the K+ cation conductivity, since the 2-orders-of-magnitude increase in the anion reorientational mobility observed between 297 and 311 K coincides with a large increase in K+ conductivity.

Journal Keywords: Anions; Crystal structure; Physical and chemical processes; Boron; Energy

Subject Areas: Chemistry

Instruments: I11-High Resolution Powder Diffraction

Other Facilities: MS-powder beamline at Swiss Light Source

Added On: 22/02/2021 11:05

Discipline Tags:

Physical Chemistry Chemistry Materials Science Inorganic Chemistry

Technical Tags:

Diffraction X-ray Powder Diffraction