Eur. Phys. J. B 52, 15-21 (2006)
https://doi.org/10.1140/epjb/e2006-00269-7

Study of temperature dependent atomic correlations in MgB₂

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

Corresponding author: ^a gaetano.campi@romal.infn.it

Received: 6 December 2005
Revised: 13 April 2006
Published online: 6 July 2006

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.