Structure and lattice dynamics of solid solutions (1 − x)BiFeO3-xANbO3 (A = K, Na)

PZT-like structural phase transitions in the BiFeO3–KNbO3 solid solution

“…Surprisingly the spectra collected for the Bi 0.30 K 0.70 Fe 0.30 Nb 0.70 O 3 material resembles that of Amm2 and is most likely due to phase segregation. As with our diffraction studies, we found no evidence in the Raman spectra for the Pbnm phase reported by Teslenko et al 11,12 Preliminary magnetic and electrical data exhibit some interesting behaviour yet confirm the inhomogeneous nature of the samples. Variable temperature zero-field cooled (ZFC) and field cooled (FC) data collected for materials with x ≥ 0.5 (given in the ESI †) showed curves consistent with paramagnetic behaviour.…”

“…The work by Teslenko et al suggests that the transition from R3c to P4mm symmetry occurs through an intermediary non-polar Pbnm phase. 11,12 We find no evidence for a possible Pbnm phase in any of our data either as a primary or secondary phase.…”

“…11 They later expanded this study to more in-depth characterisation of x = 0, 0.3, 0.5, 0.7 and 1.0 in Bi 1−x K x Fe 1−x Nb x O 3 . 12 These authors postulate that materials between 0 ≤ x ≤ 0.25 are characterised with the same polar, R3c symmetry exhibited by the parent BFO material. This is followed by a non-polar, Pbnm → polar, P4mm → polar, Amm2 series of phase transitions at approximately x = 0.55 and 0.85 respectively.…”