2012/09/14 by K. H. Michel, A. V. Nikolaev, Michel, K. H. +2
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #FOS: Physical sciences #Fullerene Chemistry and Applications #High-pressure geophysics and materials #Materials Science (cond-mat.mtrl-sci) #Nuclear physics research studies #Statistical Mechanics (cond-mat.stat-mech) #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.mtrl-sci #cond-mat.stat-mech #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.1209.3232
12 pages, 4 figures, 1 table
arxiv created 2012/09/14 · openalex publication_date 2012/09/14 · arxiv updated 2012/09/17 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Starting from a model of 4f-electron generated quadrupolar densities on a compressible fcc lattice, the elastic anomalies at the Fm3m -> Pa3 phase transition are studied by means of analytical theory. The model is taken as representative for the gamma-alpha phase transition in Ce. The coupling of the (linear) lattice displacements to the square of the quadrupolar orientational density fluctuations renormalizes the elastic constants. The condensation of the quadrupolar densities into the orientationally ordered Pa3 structure is studied as function of temperature and pressure. Precursor effects of the transition lead to an anomalous softening of the elastic constant c11 while c44 exhibits no such softening. The theoretical results are in excellent qualitative agreement with pressure experiments on the elastic constants (equivalently on sound velocities) at the gamma-alpha transition in Ce. Lattice dynamical analogies in theory and striking similarities in experimental results with the Fm3m -> Pa3 transition in C60 fullerite are discussed.