Evidence for a first-order transition from monoclinicαto monoclinicβphase inBiFeO3thin films

Abstract

We report a temperature-dependent high-resolution x-ray diffraction investigation of 200-nm epitaxial BiFeO 3 thin films grown on ͑001͒ SrTiO 3 . We find that BiFeO 3 undergoes two high-temperature transitions: a first-order ␣-␤ phase transition between 745 and 780°C and a more diffuse transition toward the ␥ phase at 860°C. Reciprocal space maps reveal that thin films remain monoclinic crossing the ␣-␤ phase transition. Linear extrapolation of the in-plane lattice parameters to higher temperatures appears to rule out cubic symmetry for the ␥ phase.

Phase Diagram of BiFeO3/LaFeO3 Superlattices: Antiferroelectric‐Like State Stability Arising from Strain Effects and Symmetry Mismatch at Heterointerfaces

“…Such T* independent of the strain have been detected in BFO thin films and bulk materials and seems to involve Fe-O bond length changes. [39][40][41] In bulk it has been attributed to surface transition (within a few nm) and proximity of the Neel temperature (267°C and 367°C for BFO and LFO respectively in bulk) may explain its origin. The anomalies observed at high temperature could be interpreted as a change of orientation or structural domains in the SLs and in order to rule out such possibilities we performed reciprocal space mapping at different temperatures.…”

Phase Transitions, Phase Coexistence, and Piezoelectric Switching Behavior in Highly Strained BiFeO3 Films

“…A linear fit predicts these peaks' disappearance at 867 ± 100 °C, which we take as an estimate of the Curie temperature of T' BiFeO 3 . Therefore, T' BiFeO 3 likely exhibits a Curie temperature fairly close to that of R' films ( T c ≈ 760 °C) …”

Grain and grain boundary effects in Ca2+ doped BiFeO3 multiferroic ceramics

“…The most extensively studied multiferroic systems are based on pure and doped BiFeO 3 and BiMnO 3 7–9. These materials are being investigated both in ceramic as well as thin film forms 8, 10–14. Many synthesis routes ranging from solid‐state thermo‐chemical to template‐based synthesis are being employed for preparing such materials 15–17.…”