Anion disorder in LnF3 (Ln = La, Ce, Pr) crystals
Source abstract
Abstract
The mechanism of lattice “melting” in tysonite-structure superionic trifluorides is analyzed in relation to the structure of LaF 3 crystals. The ion displacements within the unit cell are shown to correlate with the dynamics of the Raman scattering parameters of the crystals. The frequency and intensity of the lines at 370, 392 (LaF 3 ), 376, and 404 cm −1 (PrF 3 ) show anomalous behavior in three temperature ranges: 160–180, 240–280, and 420–460 K. The anomalies in the two higher temperature ranges are due to lattice disordering in the superionic transition region. The scattering in the range 160–180 K is tentatively attributed to fluoride ion displacements in split sites with a few potential wells. It is shown based on a split-site model that the thermally activated formation of interstices comparable in size to the mobile fluoride ion is an inherent feature of the LnF 3 structure.
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Research context
OpenAlex topics: Inorganic Fluorides and Related Compounds · Luminescence Properties of Advanced Materials · Solid-state spectroscopy and crystallography
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (16)
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