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This work is a study of phase transformation in (001)-cut Pb(Fe1/2Nb1/2)1-xTixO3 (x=48%) single crystals by means of dielectric permittivity, domain structure, and in situ x-ray diffraction. A first-order T(TNT)-C(TNT) phase transition was observed at the Curie temperature TC≅518 K upon zero-field heating. T, TNT, and C are tetragonal, tetragonal nanotwin, and cubic phases, respectively. T(TNT) and C(TNT) indicate that minor TNT domains reside in the T and C matrices. Nanotwins, which can cause broad diffraction peak, remain above TC≅518 K and give an average microscopic cubic symmetry in the polarizing microscopy. Colossal dielectric permittivity (>104) was observed above room temperature with strong frequency dispersion. This study suggests that nanotwins can play an important role in relaxor ferroelectric crystals while phase transition takes place. The Fe ion is a potential candidate as a B-site dopant for enhancing dielectric permittivity. [ABSTRACT FROM AUTHOR]

This work is a study of the thermal stability of (001)-cut Pb(Mg1/3Nb2/3)1-xTixO3 (x=0.30) single crystals before and after an electric (E)-field poling by means of dielectric permittivity, hysteresis loop, domain structure, polarization current, and x-ray diffraction. An R(RNT)-R(RNT)/T(TNT)-T(TNT)-C transition sequence was observed upon heating in the unpoled sample. R, RNT, T, TNT, and C are the rhombohedral, rhombohedral nanotwin, tetragonal, tetragonal nanotwin, and cubic phases, respectively. R/T indicates coexistence of the R and T phases. R(RNT) and T(TNT) indicate that the RNT and TNT structures mimic monoclinic phases in the R and T matrices, respectively. After a prior E-field poling, an R(RNT)-T(TNT)-C phase sequence takes place upon heating. The dielectric permittivity and current density evidenced an additional polarization at 355 K, which is associated with the vanishing of the dielectric dispersion, which reappears near 410 K and remains up to the Burns temperature TB=510 K. This study suggests that nanotwins (RNT and TNT) can play an important role in high-strain piezoelectric crystals while phase transition takes place. Under E=38 kV/cm, [001] T domains randomly appeared in the matrix, suggesting that the matrix consists of a glassy matrix and ferroelectric nanoclusters. [ABSTRACT FROM AUTHOR]

The dielectric permittivity, domain structure, and in situ x-ray diffraction techniques are used to study the phase transformation in (001)-cut Pb[([Fe.sub.1/2][Nb.sub.1/2]).sub.1-x][Ti.sub.x[O.sub.3] (x=48%) single crystals. The results provide insight into the significant role of nanotwins in relaxor ferroelectric crystals during phase transition and the Fe ion as potential candidate at a B-site dopant for enhancing dielectric permittivity.

The thermal stability of (001)-cut Pb[([Mg.sub.1/3][Nb.sub.2/3]).sub.1-x][Ti.sub.x][O.sub.3] (x = 0.30) single crystals before and after an electric (E)-field poling is analyzed by using dielectric permittivity, hysteresis loop, domain structure, polarization current and x-ray diffraction. The study has shown that nanotwins have played a vital role in high-strain piezoelectric crystals while phase transition has taken place.