Thermally activated dynamics of the tilts of the CuO6 octahedra, hopping of interstitial O, and possible instability towards the LTT phase in La2CuO4+δ
- Cordero, F.
- Grandini, Carlos Roberto
- Cannelli, G.
- Cantelli, R.
- Trequattrini, F.
- Ferretti, M.
DOIAbstract
The anelastic spectrum (dynamic Young's modulus and elastic energy absorption) of La2CuO4+δ has been measured between 1 and 700 K with 0<δ<0.02. The spectrum of stoichiometric La2CuO4 in the low-temperature orthorhombic (LTO) phase is dominated by two intense relaxation processes which cause softenings of 16% around 150 K and 9% below 30 K at f∼1 kHz. The relaxation at 150 K is attributed to the presence of a fraction of the CuO6 octahedra which are able to change their tilted configuration by thermal activation between orientations which are nearly energetically equivalent, possibly within the twin boundaries. The relaxation below 30 K is governed by tunneling, and involves a considerable fraction of the lattice atoms. It is proposed that ...
Add to ORKG