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In this work, we report a giant strain (0.42%) in lead-free ceramics of (1– x) (0.79Bi 0.5 Na 0.5 TiO 3 –0.20 Bi 0.5 K 0.5 TiO 3 –0.01NaNbO 3)– x SrTiO 3 with x =0.03. Most importantly, ultra-high temperature stability was simultaneously achieved under this giant strain with the variation less than 10% in the range of 20 °C and 140 °C. Systematic temperature dependent Raman spectra measurements and Ginzburg–Landau–Devonshire thermodynamic theory analysis revealed that the intrinsic lattice strain and electric field induced relaxor-ferroelectric phase transition provide reverse strain response with the increase of temperature, jointly conducive to the ultra-high temperature stability of strain property. These materials are extremely competitive in practical application of actuators. Image, graphical abstract [ABSTRACT FROM AUTHOR]

We report the electric-field-induced ferroelectric (FEIN) to antiferroelectric (AFE) phase transition that is tuned by the poling temperatures in 0.89Bi0.5Na0.5TiO3-0.06BaTiO3-0.05K0.5Na0.5NbO3 (0.89BNT-0.06BT-0.05KNN) ceramics. Phase transition and pyroelectric behaviors of the ceramics were investigated as functions of temperature and electric field. Pyroelectric coefficient peaks of (3 ∼ 6.5) × 10-8 C cm-2 K-1 are detected at about 10 °C above the poling temperatures for the samples poled at different temperatures. The poling temperature tuned pyroelectric behaviors are attributed to the FEIN to AFE phase transition when the temperature increases. [ABSTRACT FROM AUTHOR]

The electric field dependence on the dielectric properties of the porous ceramics was studied theoretically. The dielectric constant of the porous ceramics under certain direct current (dc) bias field and the real strength electric field in the porous ceramics were given quantitatively. As the pore can share the electric field, the tunability of the porous ceramics will be decreased when the porosity increases. The dielectric constant evolution of Ba0.6Sr0.4TiO3-based porous ceramics with the dc bias electric field can be successfully explained by our theoretical results. Taking Ba0.6Sr0.4TiO3-based porous ceramic samples, for example, there is good correspondence between the theoretical and the experimental results. [ABSTRACT FROM AUTHOR]

Well-defined polarization-electric field double hysteresis loops are rarely observed in pure NaNbO3 (NN) ceramics due to the metastability of the field-induced ferroelectric phase. In order to stabilize the antiferroelectric phase, various ABO3-type binary oxides were incorporated into a NaNbO3 ceramic, where the B-site is occupied with transition elements. In this work, CaSnO3 was chosen to construct the NaNbO3-based solid solution by reducing the Goldschmidt tolerance factor and ionic polarizability. X-ray diffraction patterns, transmission electron microscopy images, and Raman spectra indicate enhanced antiferroelectricity. Typical double hysteresis loops were also observed from polarization-electric field measurements in ambient conditions with slightly weakened maximum polarization as the content of CaSnO3 increased. Our results reveal the generality of this strategy and pave the way for various applications involving high-power energy for NaNbO3-based ceramics. [ABSTRACT FROM AUTHOR]

The ferroelectric hysteresis loops of 63PbTiO3-37BiScO3 ceramics were measured under sinusoidal electric fields in the range of frequency from 0.1 to 100 Hz and field from 5 to 55 kV/cm. The fitting results showed two linear relations existed between the logarithm of hysteresis area and the logarithm of the amplitude of field E0 in the first and third field region. In the second region, no linear relation existed due to polarization reversal. These three-stage behaviors were distinct from the existing two-stage behaviors. The slopes in the third stage increase with the increasing of frequency, which can be attributed to dielectric loss under high frequency. [ABSTRACT FROM AUTHOR]

The ferroelectric hysteresis loops of 63PbTiO3-37BiScO3 bulk ceramics were measured under sinusoidal electric fields over a frequency range of 1 Hz-100 Hz and amplitude range of 10 kV/cm-50 kV/cm. Scaling relation of ferroelectric hysteresis loops area 〈A〉 versus frequency f and the amplitude of field E0 for the saturated loops is [image omitted], while the scaling relation for the unsaturated loops takes the form of [image omitted]. [ABSTRACT FROM AUTHOR]

(Pb0.325Sr0.675)TiO3 (PST) ceramics were prepared by a traditional solid-state reaction technique. The dielectric and enhanced pyroelectric properties of PST ceramics were investigated under a DC bias field. The dielectric permittivity and dielectric loss of PST ceramics at Curie temperature were 2.97 × 10-4 and 0.006 without DC bias field, respectively. With a DC electric field of 0-500 V/mm, the maximum pyroelectric coefficient and the largest figure of merit (Fd) of PST ceramics were obtained, about 60 × 10-8 C cm-2 K-1 and 26 × 10-5 Pa-1/2, respectively. PST ceramics with such superior electric field enhanced pyroelectric properties have the potential for uncooled focal plane array detectors application. [ABSTRACT FROM AUTHOR]

The grinding strain induced ferroelectric (FE) to antiferroelectric (AFE) phase transition with associated hysteresis loops tuning were found in bulk Pb 0.99 (Zr 0.97 Ti 0.03) 0.98 Nb 0.02 O 3 ceramics. The induced AFE phases can keep stable unless applying heat treatment or electric field. The atomic-scale characterizations reveal that the perfect coherent FE/AFE interface appears either diffuse or sharp depending on its relative orientation to polarization. The induced surface AFE layers on FE bulk can tune hysteresis loops from symmetric to asymmetric and this effect increased with the decrease of thickness of samples. These findings provide new pathway for manipulate phase state and discover novel properties in ferroics. Grinding strain induced ferroelectric-antiferroelectric phase transition with hysteresis loops tuning in bulk ceramics. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: Porous Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics with different pore size were prepared by solid-state sintering in air. The microstructural effect on the properties has been systematically investigated by SEM, ferroelectric hysteresis, strain–electric field curves and breakdown strength measurements. The results demonstrate that the microgeometry has a subtle effect on the ferroelectric and dielectric properties. However, the results also demonstrate that the electric field induced strain and the dielectric breakdown strength decreases with the increase of pore size. [Copyright &y& Elsevier]