Thermodynamics and magnetic properties of LaPb3 and CePb3

Thermal expansion coefficient between 77 and 900 K, isothermal compressibility in the 0–8 GPa pressure range, magnetic susceptibility between 1.3 and 800 K and the heat capacity at constant pressure in the 20–300 K temperature range were determined for the LaPb3 and CePb3 compounds. Both the thermal expansion (3α) and the isothermal compressibility (kT) of the two phases show behaviours similar and free from singularities. In the standard conditions 3α is 53 × 10−6 K−1 for LaPb3 and 60 × 10−6 K−1 for CePb3; kT is 5.3 × 10−12 Pa−1 and 8.6 × 10−12 Pa−1 respectively for LaPb3 and CePb3. The magnetic susceptibility measurements show that in LaPb3 there is no evidence of a localized magnetic moment on the La atoms, and in CePb3 the magnetic moment localized on the Ce atoms is 2.32 μB, close to that one expected for Ce3+ ions. The thermal behaviours of the molar heat capacity at constant pressure and the calculated Cν+γT values, at high temperatures, are very similar for the two compounds. At low temperatures, an anomalous enhancement of the electronic contribution to the specific heat (γ) found for CePb3 is interpreted as an evidence of the possible occurrence, in the phase, of a Ce valence fluctuation at low temperatures.