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Stress-Induced Phase Transitions in Polycrystalline BaCaTiZrO3

Field induced phase transitions are an important phenomena in ferroelectric materials. They have been extensively shown in single crystal ferroelectrics, such as Pb(Mg1/3Nb2/3)O3xPbTiO3, but are more difficult to observe in polycrystalline samples due to the random orientation of the crystallite grains. Recent measurements have shown an apparent compressive stress-induced phase transition in polycrystalline BCZT ceramics at room temperature, indicated by a jump in the permittivity at approximately – 20 MPa (Fig. 1).

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Figure 1. Permittivity as a function of compressive stress for BCZT.

During this project, this anomaly will be investigated using stress dependent dielectric and piezoelectric characterization techniques as well as stress-dependent structural investigations. An additional goal will be to utilize the soft nature of BCZT to develop a highly tunable bimorph heterostructure (Fig.2).

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Figure 2. Bimorph actuator used to tune the permittivity of a thin BaTiO3 film.

 

Further Information
1. Liu and Ren “Large Piezoelectric Effect in Pb-Free Ceramics” Physical Review Letters, vol 103 (2009)
2. Schader et al. “Influence of uniaxial stress on the ferroelectric-to-paraelectric phase change in barium titanate” Journal of Applied Physics, vol 113 (2013)
3. Ci et al. “Large electrical manipulation of permittivity in BaTiO3 and Pb(Zr,Ti)O3 bimorph heterostructure” Applied Physics Letters, vol 105 (2014)

Contact Information
Prof. Kyle G. Webber