Stability Of Antiferroelectric Phase Research Articles

High antiferroelectric stability and large electric field–induced strain in MnO2-doped Pb0.97La0.02(Zr0.63Sn0.26Ti0.11)O3 ceramics

Crystal structure and electrical properties of MnO2-doped Pb0.97La0.02(Zr0.63Sn0.26Ti0.11)O3 antiferroelectric ceramic were studied in detail in this article. X-ray diffraction analysis showed that all specimens took on single tetragonal antiferroelectric structure, and antiferroelectric phase stability enhanced with the increase of MnO2 addition, which was because that the substitution of Mn2+ or Mn3+ with large ion radius for B-site Ti4+ decreased the tolerance factor of the ceramic. In addition, it was observed that different from Mn doping reducing Tm of ferroelectric ceramics, Tm of antiferroelectric ceramics increased with the addition of MnO2, which is for the reason that MnO2 addition enlarged the zone of antiferroelectric phase. Furthermore, by increasing MnO2 content, the strain first increased and then decreased. Meanwhile, the value improved obviously as the measuring frequency decreased. The largest electric field–induced strain of 0.65% was obtained in the specimen with 0.2 mol% MnO2 doping at the frequency of 1 Hz, which lay a foundation for preparing actuator with high strain energy density.

Enhanced antiferroelectric stability and electric-field-induced strain properties in rare earth-modified Pb(Zr0.63Sn0.26Ti0.11)O3 ceramics

Pb0.97Ln0.02(Zr0.63Sn0.26Ti0.11)O3 ceramics with large electrically induced strain were fabricated by doping the base composition with rare earth ions. The enhancement of strain was because the substitution of rare earth ions for Pb2+ could decrease the tolerance factor of the ceramics and improve the stability of antiferroelectric phase. In addition, it was found that the electrically induced strain increased as the measuring frequency decreased; this was attributed to more complete domain reversal at the low frequency. The maximum electrically induced strain of 0.66% was obtained in Pb0.97Sm0.02(Zr0.63Sn0.26Ti0.11)O3 ceramics at the frequency 1 Hz.

The Influence of Cyanoterminated Compounds on the Stability of Antiferroelectric Phase

Three bicomponent mixtures coming from the system in which antiferroelectric phase is obtained by induction as well as compound having antiferroelectric phase by itself were dopped with different cyanoterminated compounds. The influence of dopants structure on the stabilization of antiferroelectric and induced antiferroelectric phase have been tested by miscibility method in the range up to 0.2 molar fraction of dopants. Very small destabilization of antiferroelectric phase for several cyanoterminated dopants in this range is observed. Longer rigid core and longer terminal chain favour stabilization of antiferroelectric phase.

Effect of BiAlO 3 modification on the stability of antiferroelectric phase in PbZrO 3 ceramics prepared by conventional solid state reaction

In this paper, we report on the polycrystalline (Pb (1−3 x/2) Bi x )(Zr 1−3 x/4 Al x )O 3 (PZO–BAO) ceramics, with x = 0.0–0.3, prepared by conventional solid state reaction. The crystal structure and thermal and dielectric properties of the sintered ceramics were investigated as a function of composition by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and dielectric spectroscopy. The results indicated that the presence of BiAlO 3: BAO in the solid solution decreased the structural stability of the overall perovskite phase. Dielectric, thermal and P–E hysteresis results confirmed that no ferroelectric intermediate phase was seen in the PZO–BAO system. An antiferroelectric phase can be stable in a wide temperature range, indicating that BAO enhanced antiferroelectric phase stability in perovskite PZ manifests by “square” antiferroelectric behavior. Therefore, the (Pb (1−3 x/2) Bi x )(Zr 1−3 x/4 Al x )O 3 solid solution offers a material system for high-energy-storage capacitors and electromechanical transducers.

The Synthesis and Mesomorphic Properties of Some Novel Antiferroelectric Liquid Crystals

Several esters have been synthesised that exhibit the antiferroelectric smectic C phase. The core structures, like virtually all antiferroelectric materials, are very similar to that of MHPOBC. Lateral fluoro substituents have been used to reduce melting points and to investigate their effect on mesomorphic properties, spontaneous polarisation and tilt angle. A new device format reported by Lagerwall requires antiferroelectric liquid crystals with a 45° tilt angle. Novel antiferroelectric materials were prepared with fluoro substituents in lateral positions and in a terminal chain to provide low melting points, high antiferroelectric phase stability, high spontaneous polarisation and tilt angles of up to 45°. The synthetic routes to the novel materials are discussed, and the transition temperatures, tilt angles and spontaneous polarisations are compared to those of known materials.

Effect of substituents with different valences on antiferroelectric stability of antiferroelectric lead zirconate ceramics

The effect of lower valent substituents on the stability of the antiferroelectric phase of lead zirconate was studied by dielectric spectroscopy, Sawyer–Tower polarization methods, and electron diffraction techniques. The stability of an intermediate ferroelectric phase region was found to be enhanced with increasing lower valent substitution concentration. The influences of substituents of different ionic size and valence on the stabilization of the intermediate ferroelectric phase were differentiated. In general, lower valent substituents, such as K+ and Fe3+ affected antiferroelectric phase stability more significantly than higher valent ones.