Elastic anomaly and internal friction of Ba0.5Sr0.5Co0.8Fe0.2O3-δ and La0.58Sr0.4Co0.2Fe0.8O3-δ

Elastic modulus and internal friction of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) and La0.58Sr0.4Co0.2 Fe0.8O3-delta (LSCF) were determined from resonance frequencies and damping behavior, respectively, using an impulse excitation method. An elastic anomaly for BSCF around 476 K, with a corresponding peak in the internal friction, is attributed to the experimentally confirmed spin transition of Co3+. LSCF is in a ferromagnetic state below similar to 220 K and in a paramagnetic state above similar to 250 K. The elastic modulus of LSCF exhibits an anomaly between 473 and 1113 K, which is attributed to a transition from rhombohedral to cubic symmetry.