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Study of temperature dependent atomic correlations in MgB2 |
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| Authors: | G. Campi E. Cappelluti Th. Proffen X. Qiu E. S. Bozin S. J.L. Billinge S. Agrestini N. L. Saini A. Bianconi |
| Affiliation: | (1) Istituto di Cristallografia, CNR, sezione di Monterotondo, Area della Ricerca di Roma - Montelibretti, P.O. Box 10, 00016 Monterotondo St., Italy;(2) Istituto dei Sistemi Complessi, CNR-INFM, v. dei Taurini 19, 00185 Roma, Italy;(3) Dipartimento di Fisica, Università di Roma “La Sapienza”, P. le Aldo Moro 2, 00185 Roma, Italy;(4) Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA;(5) Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA |
| Abstract: | We have studied temperature evolution of the local as well as the average crystal structure of MgB2 using real-space atomic pair distribution function (PDF) measured by high resolution neutron powder diffraction in a wide temperature range of T=10–600 K. We find small positive correlation factors for the B–B and B–Mg pairs, determined by mean-square displacements (MSD) and the mean-square relative displacements (MSRD). We analyze the PDF using both Einstein and force constant models finding a good agreement between the experimental data and the two models. This indicates that B and Mg atomic correlations are not sensitive to the details of phonon dispersion. |
| Keywords: | 61.12.-q Neutron diffraction and scattering 63.20.-e Phonons in crystal lattices 74.70.Ad Metals alloys and binary compounds (including A15, MgB2, etc.) |
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