Anomalous temperature dependence of the low-frequency vibrational density of states in vitreous B2O3 |
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| Institution: | 1. Department of Experimental Oncology, European Institute of Oncology - IEO IRCCS, Milan, Italy;2. Department of Biomedical Sciences, University of Padova, Padua, Italy;3. Department of BioSciences, University of Milano, Milan, Italy;5. Genomics Unit, Firc Institute for Molecular Oncology, Milan, Italy;1. Department of Radiophysics, Faculty of Physics, Vilnius University, Saulėtekio ave. 3, LT-10222 Vilnius, Lithuania;2. Institute of Inorganic Chemistry, Riga Technical University, Paula Valdena 3/7, LV-1048 Riga, Latvia;3. Département des Oxydes et Fluorures, Institut des Molécules et Matériaux du Mans (IMMM, UMR 6283), Avenue O. Messiaen, 72085 Le Mans Cedex 9, France |
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| Abstract: | Inelastic neutron-scattering measurements of v-B2O3 reveal an upshift in energy of the first moment of the vibrational density of states for frequencies below ≈ 15 meV as temperature increases from 20 to 300 K. Such a stiffening is at odds with predictions based on some current approaches. Instead, the present result and related anomalies in specific heat and other microscopic and transport properties can be understood in terms of anharmonic motions at low frequencies. The atomic origin of the anharmonicity, and its consequence for the thermodynamical behavior are examined by molecular-dynamics simulations. |
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