Browsing by Author "Manley, ME"

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    Intrinsically localized vibrations and the mechanical properties of α-uranium.
    (Elsevier, 2007-10-11) Manley, ME; Yethiraj, M; Sinn, H; Volz, HM; Alatas, A; Lashley, JC; Hults, WL; Lander, GH; Thoma, DJ; Smith, JL
    Recent experiments have indicated that the high-temperature properties of α-uranium may be strongly influenced by the formation of randomly distributed intrinsically localized vibrational modes, just a few atoms across in size. One observation was a loss of mechanical ductility that coincided with the formation of the intrinsically localized mode (ILM). Here, we consider this observation in more detail. In particular, we use the anisotropic thermal expansion behaviour to estimate the strains associated with each ILM and consider the implications for the forces between ILMs and the defects responsible for mechanical deformation. In the process we also suggest that an unusual transition from positive to negative thermal expansion along the [0 1 0] direction may be caused by the formation of ILMs. © 2007, Elsevier Ltd.
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    (Mg,Mn,Fe,Co,Ni)O: a rocksalt high-entropy oxide containing divalent Mn and Fe
    (American Association for the Advancement of Science, 2023-09-20) Pu, Y; Moseley, D; He, Z; Pitike, KC; Manley, ME; Yan, J; Cooper, VR; Mitchell, VD; Peterson, VK; Johannessen, B; Hermann, RP; Cao, P
    High-entropy oxides (HEOs) have aroused growing interest due to fundamental questions relating to their structure formation, phase stability, and the interplay between configurational disorder and physical and chemical properties. Introducing Fe(II) and Mn(II) into a rocksalt HEO is considered challenging, as theoretical analysis suggests that they are unstable in this structure under ambient conditions. Here, we develop a bottom-up method for synthesizing Mn- and Fe-containing rocksalt HEO (FeO-HEO). We present a comprehensive investigation of its crystal structure and the random cation-site occupancy. We show the improved structural robustness of this FeO-HEO and verify the viability of an oxygen sublattice as a buffer layer. Compositional analysis reveals the valence and spin state of the iron species. We further report the antiferromagnetic order of this FeO-HEO below the transition temperature ~218 K and predict the conditions of phase stability of Mn- and Fe-containing HEOs. Our results provide fresh insights into the design and property tailoring of emerging classes of HEOs. © 2024 American Association for the Advancement of Science.