Interrelation of ferroelectricity and tilting in perovskites using the phase transitions in PbZr1−xTixO3 as an example

•The R3m-R3c phase transition in PbZr1−xTixO3 (0.07 ≤ x ≤ 0.24) is studied.•A tricritical point is located at x ≈ 0.17 at the R3m-R3c boundary.•A theoretical model is proposed describing the dome-shaped form of this boundary.•Implications of the obtained results for perovskites in general are discussed.

The compounds belonging to the perovskite class often exhibit complex temperature- or pressure-induced sequences of ferroelectric or structural phase transitions. The understanding of interaction between such lattice instabilities, which are different in nature, is an important problem due to wide range of applications of perovskite-based materials. One of the common examples of such interaction is the co-existence of ferroelectricity and octahedral tilting, which is most pronounced in PbZr1−xTixO3 (PZT) solid solutions. In this work using dielectric and pyroelectric measurements we study the octahedral tilting phase transition in PZT (0.07 ≤ x≤ 0.24), which has a pronounced dome-shaped form in the T – x phase diagram and a tricritical point at x ≈ 0.17. Based on crystallographic arguments we further suggest a phenomenological model of phase transitions in PZT capable of describing the dome-shaped form of the R3m – R3c octahedral tilting phase transition line as well as positions of the tricritical points. The implications of the obtained results for perovskites in general are discussed.

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