Résumé: The low:temperature variations of the thermal expansion coefficient [alpha](T ) of a PrBa2Cu3O6+x ceramic are reported for two oxygenation states (x=0.4 and 0.9). They show a peak at the ordering temperature of Pr deduced from the susceptibility [chi](T ) and the specific heat Cp(T ), i.e. at TN=9.5 and 14.5 K, for x=0.4 and 0.9, respectively. The deduced Gruneisen parameter [Gamma]eff is rather large, show almost no anomaly at TN, but a sharp increase below [approximate]5 K. The origin of these variations is discussed in terms of magnetic behaviour of the Pr and Cu sublattices.

Langue: Anglais