Pb(Zr1-xTix)O3 with very high content of Zr shows an antiferroelectric ground state and possesses an exceptional property: the coexistence of several built-in structural instabilities at high temperatures. This leads to the possibility of their successive condensation on cooling to trigger a sequence of phase transitions, instead of reaching directly the antiferroelectric state, as in pure PbZrO3. This peculiar behaviour is more pronounced in compositions near the antiferroelectric morphotropic phase boundary and the tricritical point around room temperature, as Pb(Zr0.95Ti0.05)O3 (PZT 95/5), where three phases are energetically available.
Raman scattering experiments performed out of the thermodynamical equilibrium revealed a complex and hysteretic thermal behaviour of the phase transition dynamics, due to the inhomogeneous microstructure and the coexistence of regions with different phases within the samples. A way to control the thermal development of these different phases is to selectively condense the different instabilities by an external parameter such as temperature, hence creating a sequence of phase transitions instead of a direct phase transition.
Our results, obtained under many different experimental conditions and specific pre-history, suggest that ceramics with composition near PZT 95/5 are potential materials for novel 3-state thermal switches. An innovative approach of phase-control is proposed, based on the thermal behaviour of the intermediate polar states observed and using small temperature gradients by appropriate heating-cooling cycles around room temperature.
E. Buixaderas, C. Milesi-Brault, P. Vaněk, J. Kroupa, F. Craciun, F. Cordero, C. Galassi, Peculiar Dynamics of Polar States at the Morphotropic Phase Boundary of Antiferroelectric Pb(Zr1-xTix)O3, Acta Materialia, 119208 (2023), online.
Contact person: Elena Buixaderas