Growth and electrical properties of (Mn,F) co-doped 0.92Pb(Zn1/3Nb2/3)O3-0.08PbTiO3 single crystal

The growth and characterization of (Mn,F) doped Pb(Zn1/3Nb2/3)O-3-PbTiO3 (PZNT) single crystals are reported in this paper. The typical single crystal obtained is up to 30 mm size with dark brown color. The crystal lattice parameters of doped PZNT crystal are slightly decreased compared to the pure one. The room temperature dielectric permittivity along <0 0 1> direction is about 6000, which is lower than that of the pure PZNT8 because of the dopants. The Curie temperature of the doped crystal is about 180degreesC while the ferroelectric phase transition temperature is around 100degreesC, which are higher than those of the pure PZNT8 single crystal. The remnant polarization and coercive field of <0 0 1> oriented doped crystal measured at 1 Hz and 10 kV/cm field are about 27 muC/cm(2) and 4.2 kV/cm, respectively. The room temperature mechanical quality factor is similar to 300. Piezoelectric coefficient of <0 0 1> oriented doped crystal is higher than 3500 pC/N and the longitudinal electromechanical coupling factor is larger than 93%. The piezoelectric properties of doped PZNT single crystal with temperature and orientations are also reported in this paper. The valence state of the manganese dopant was determined by electron spin resonance, indicating no Mn4+ in the crystals, suggesting the valence of manganese ions in PZNT crystals may be 2+, which acts as a hardener, stabilizes the domain wall and pins the domain wall motion, on the other hand, the dopant will enter Ti4+ position, shifting the crystal composition to higher PT content. (C) 2004 Elsevier B.V. All rights reserved.