Multiple High-Temperature Transitions Driven by Dynamical Structures in NaI
M. E. Manley, J.R. Jeffries, H. Lee, Nicholas P. Butch, D. L. Abernathy
Multiple, consecutive high-temperature transitions in NaI involving dynamical order and/or localization in the energy-momentum spectrum but not in the average crystal structure are revealed by lattice dynamics, x-ray lattice spacing, and heat capacity measurements. Distinctive energy-momentum patterns and lattice distortions indicate dynamical structures forming within randomly stacked planes, rather than the isolated point-defect-like intrinsic localized modes predicted. Transition entropies are accounted for by vibrational entropy changes and the transition enthalpies are explained by strain energy of forming stacking-fault-like planer distortions deduced from x-ray diffraction peak shifts. The vibrational entropy of the dynamical structures stabilizes surrounding elastic distortions.
, Jeffries, J.
, Lee, H.
, Butch, N.
and , D.
Multiple High-Temperature Transitions Driven by Dynamical Structures in NaI, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=916279
(Accessed July 31, 2021)