Interpretation of T(m) and T* in relaxor ferroelectric 0.93Pb(Zn₁/₃Nb₂/₃)O₃-0.07PbTiO₃

The dielectric property of relaxor ferroelectric 0.93Pb(Zn?/?Nb?/?)O?-0.07PbTiO? single crystals (PZN-0.07PT) is studied to investigate the ferroelectric phase transition. The temperature dependence of the susceptibility of the central peak in the light scattering shows a very similar behavior to the real part of the dielectric constant, indicating that the diffuse peak in the temperature dependence of the dielectric constant is induced by relaxation of the polarization. We suggest that the origin of the relaxation above T(m) is the non-180° polarization flipping of a small polar nanoregion (PNR). Additionally, the behavior of the PNRs is interpreted through both the Brillouin spectra and high-energy synchrotron-radiation powder diffraction patterns. Our results reveal that T*~ 499K is the temperature below which the growth rate of the dynamic polarization fluctuation is suppressed by the additional random electric field induced by the generation of the static PNRs.     

Pyroelectric performances of rhombohedral 0.42Pb(In₁/₂)Nb₁/₂)O₃-0.3Pb(Mg₁/₃Nb₂/₃)O₃-0.28PbTiO₃ single crystals

Relaxor-based ferroelectric single crystals xPb(In?/?)Nb?/?)O?-yPb(Mg?/?Nb?/?)O?-(1-x-y)PbTiO? {PIMNT [100x/100y/100(1-x-y)]} have been grown by a modified Bridgman technique. The as-grown PIMNT (42/30/28) crystal with rhombohedral perovskite-type structure shows higher Curie temperature TC ~ 187 °C, and higher ferroelectric rhombohedral-to-tetragonal phase transition temperature TRT ~ 152 °C, both about 50 °C higher than those found for 0.71Pb(In?/?)Nb?/?)O?-0.3Pb(Mg?/?Nb?/?)O?-0.29PbTiO? crystals. Moreover, as a core parameter of pyroelectric material, the detectivity figures-of-merit of PIMNT (42/30/28) crystal are higher than other typical relaxor-based ferroelectric crystals, which primarily stems from the lower dielectric loss, making it promising candidate for infrared detector applications.     

Dielectric properties of rutile structure (Zn₁/₃B₂/₃)x(TiySn(1-y))(1-x)O₂ (B=Nb⁵+,Ta⁵+) at microwave frequencies

The microwave dielectric properties of rutile (Zn?/? B?/?)x(TiySn(1-y))(1-x)O? (B=Nb?+,Ta?+, 0.05 ≤ x ≤ 0.35, y = 0.2, 0.8) were investigated with structural characteristics. A single phase with tetragonal rutile (P4?/mnm, no. 136, Z = 2) structure was obtained through the entire range of compositions. With an increase of (Zn?/?B?/?)O? content, the dielectric constant (K) of sintered specimens with (Ti?.?Sn?.?)O? increased, whereas that of the specimens with (Ti?.?Sn?.?)O? decreased. The temperature coefficient of resonant frequency (TCF) of sintered specimens was dependent upon oxygen octahedral distortion and/or cations bond valence of the rutile structure. The quality factor (Qf) was dependent upon (Zn?/?B?/?)O? content, and the specimens with (Ti?.?Sn?.?)O? showed larger Qf values than those with (Ti?.?Sn?.?)O? for the same content of (Zn?/?B?/?)O?.     

Frequency dispersion of longitudinal ultrasonic velocity and attenuation in [001]c-poled 0.24Pb(In₁/₂Nb₁/₂O₃- 0.45Pb(Mg₁/₃Nb₂/₃)O₃-0.31PbTiO₃ single crystal

The frequency dispersion of ultrasonic velocity and attenuation in [001](c)-poled 0.24Pb(in(1/2)Nb(1/2))O(3)-0.45Pb(Mg(1/3)Nb(2/3))o(3)-0.31PbTio(3) (PIN-0.45PMN-0.31PT) ternary single crystal were measured by ultrasonic spectroscopy from 25 to 100 MHz for the longitudinal wave. It was found that the velocity has a linear relationship with the frequency f, but the attenuation has a quadratic relation with f. The attenuation and frequency dispersion of the ternary system are lower than that of the (1-x)Pb(Mg(1/3)Nb(2/3))O(3)-xPbTiO(3) (PMN-PT) binary system and the coercive field also increased by a factor of 2.5, hence, the ternary single system is superior to the corresponding binary single-crystal system for high-frequency and high-power transducer applications.