Growth and characterization of Fe-doped Pb(Zn1/3Nb2/3)O3−PbTiO3 single crystals

Abstract

Fe-doped 0.955Pb(Zn1/3Nb2/3)O3−0.045PbTiO3 (PZNT4.5) single crystals were grown using a high temperature flux technique and the dielectric, piezoelectric, electromechanical, electrostrictive, and electro-optic properties were characterized. The room temperature dielectric permittivity along the <001> direction after poling was about ∼6000 (5000−7000), increased compared to that of pure PZNT4.5 crystals ∼3000−5000. The Curie temperature (TC) and the rhombohedral to tetragonal phase transition temperature (Tr−t) of doped crystals were about 143 and 92 °C, respectively, more than 20 °C lower than that of the pure crystals. The remnant polarization (Pr) and coercive field (Ec) of <001> oriented doped crystals measured at 1 Hz and 20 kV/cm field were ∼27.3 μC/cm2 and 4.7 kV/cm, respectively, the latter significantly greater than the Ec of the pure crystals ∼3 kV/cm. Piezoelectric coefficients (d33) of <001> oriented doped PZNT4.5 crystals were ∼2500−3000 pC/N, being much higher than that of the pure (1400–2000 pC/N). The electric field induced strain was up to 0.5% with minimal hysteresis at low electric field (E∼15 kV/cm). The longitudinal electromechanical coupling factor k33 was 92%–93%. The shear mode and lateral mode properties were also studied with piezoelectric coefficient d15 of ∼3500 pC/N, d31 of ∼−1800 pC/N, and electromechanical coupling of k15∼93%, k31∼87%, respectively. The electrostrictive coefficients of Fe-doped PZNT4.5 crystals, Q11∼0.099 m4/C2, Q12∼−0.048 m4/C2, Q44∼0.012 m4/C2, and Qh∼0.0033 m4/C2 were calculated and compared to those of PZNT4.5 crystals. The apparent electro-optic coefficients of doped crystals were measured to be r33*∼118 pm/V and r13*∼29 pm/V, respectively.