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“Elastic precursor effects during the Ba1-xSrxTiO3 ferroelastic phase transitions”, published in Physical Review Research, is the result of a collaboration between ISM-CNR, Cambridge Earth Sciences (Cambridge University - England), Federal University of São Carlos (UFSCar - Brazil) and Xi’an Jiaotong University (China).
The elastic softening in the paraelastic/paraelectric phases of Ba1-xSrxTiO3 extends to the highest measured temperature (850 K) for Ba-rich compounds and can be fitted with a power law (T-Tc)^k where k ranges between 1.5 in SrTiO3 and 0.2 in BaTiO3. An alternative Vogel-Fulcher type analysis is also considered. The amplitude of the precursor softening increases continuously from SrTiO3 to BaTiO3 and is still 33% of the unsoftened Young’s modulus at 750 K in BaTiO3. This proves that the high temperature elastic properties of these materials are drastically affected by precursor softening.
The project aims at studying and improving some classes of organic and metal-organic piezoelectric materials (in which a stress causes an electric field and vice versa), which recently come into the limelight due to their unexpectedly high electromechanical coupling constants.