Growth and Di-/Piezoelectric Properties of Al-Doped PMN-30PT Single Crystals

Aluminum (Al 3+ )-doped Pb(Mg 1/3 Nb 2/3 )O 3 -30PbTiO 3 (PMN-30PT) solid solution piezo-crystals were grown by a top-seeded solution growth method. The dielectric, piezo-, and ferro-electric properties were characterized. A dispersive maximum of dielectric permittivity was found around T C = 135 °C, which does not depend on frequency. Interestingly, the rhombohedral-tetragonal phase transition, which appears at 60 °C in pure PMN-PT and thereby causes the depoling of the crystals at a relatively low temperature, has been increased to 105 °C by means of the Al 3+ -doping. This extends the upper limit of application temperature for electromechanical transducers up to the T C . The piezoelectric coefficient ( d 33 ) was found to be 2000 pC/N at room temperature. The longitudinal electromechanical coupling factor k 33 reaches 85−90%, which shows a good thermal stability upon heating up to 135 °C. The peak to peak bipolar strain was measured to be 0.25% at an electric field of up to 17 kV/cm.