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To improve densification of the (Ba0.85Ca0.15)(Hf0.1Ti0.9)O3 (BCHT) ceramics prepared via powder injection moulding, MnO2 and Li2CO3 were used as sintering aids. The BCHT ceramics doped with different Mn- and Li-amount prepared by powder injection moulding in which paraffin was used as injection binder, have rather pure perovskite structure with complicated polymorphic ferroelectric phase coexistence. Polyhedral grains combined with nearly round shape grains with increased relative density and larger gains size were obtained at appropriate doping amount, related to the formation of liquid phase during sintering and increased mobility of ions due to the generation of point defects caused by heterovalent cations doping. TheMn- and Li-doped BCHT ceramics are displacement driven ferroelectrics with apparent diffused transition characteristic at different extent, relating to the morphotropic phase boundary composition and the variation of point defects induced by doping. Comparable or surpassing electrical performance was acquired, especially the dielectric breakdown strength was increased due to the improved sinterability. With appropriate doping amount, piezoelectricity larger than 300 pC/N can be obtained in the Mn- and Li-doped BCHT ceramics poled under low electric field.

(1-x)(Ba0.75Sr0.1Bi0.1)(Ti0.9Zr0.1)O3-x(Sb0.5Li0.5)TiO3 (abbreviated as BSBiTZ-xSLT, x = 0.025, 0.05, 0.075, 0.1) ceramics were prepared via a conventional solid-state sintering method under different sintering temperatures. All BSBiTZ-xSLT ceramics have predominantly perovskite phase structures with the coexistence of tetragonal, rhombohedral and orthogonal phases, and present mainly spherical-like shaped grains relating to a liquid-phase sintering mechanism due to adding SLT and Bi2O3. By adjusting the sintering temperature, all compositions obtain the highest relative density and present densified micro-morphology, and doping SLT tends to promote the growth of grain size and the grain size distribution becomes nonuniform gradually. Due to the addition of heterovalent ions and SLT, typical relaxor ferroelectric characteristic is realized, dielectric performance stability is broadened to ~120 °C with variation less than 10%, and very long and slim hysteresis loops are obtained, which is especially beneficial for energy storage application. All samples show extremely fast discharge performance where the discharge time t0.9 (time for 90% discharge energy density) is less than 160 ns and the largest discharge current occurs at around 30 ns. The 1155 °C sintered BSBiTZ-0.025SLT ceramics exhibit rather large energy storage density, very high energy storage efficiency and excellent pulse charge–discharge performance, providing the possibility to develop novel BT-based dielectric ceramics for pulse energy storage applications. [ABSTRACT FROM AUTHOR]

(1‐x)(Li0.02Na0.5K0.48)(Nb0.95Sb0.05)O3‐x(Bi0.5Na0.5)(Zr0.97W0.01Fe0.02)O3 (LNKNbS‐xBiNZWF, x = 0.035, 0.04, 0.045, 0.05, and 0.055) lead‐free piezoceramics were fabricated by traditional solid‐state sintering method via two‐step sintering technique, where the effects of BiNZWF doping amount and ceramic processing were studied systematically. The formation of orthorhombic‐tetragonal (O‐T) phase boundary in the LNKNbS‐xBiNZWF system is confirmed by X‐ray diffraction Rietveld refinement and Raman spectroscopy, where the BiNZWF doping amount affects the O‐T phase proportion. The LNKNbS‐xBiNZWF ceramics approach to normal ferroelectrics but have apparent relaxation characteristic. Oxygen vacancies dominate the high‐temperature conduction in the LNKNbS‐0.04BiNZWF ceramics, which are generated by the volatilization of Bi and alkali metals during sintering. The LNKNbS‐0.04BiNZWF ceramics exhibit excellent electrical properties, correlating with using the two‐step sintering method, appropriate proportion of O phase and T phase, high densification and improved microstructure uniformity. [ABSTRACT FROM AUTHOR]

(1-x)(Li0.02Na0.48K0.48Ag0.02)(Nb0.95Sb0.05)O3-x(Ba0.4Bi0.3Na0.3)ZrO3 (LNKANbS-xBBiNZ, x = 0.04, 0.045, 0.05, 0.055 and 0.06) lead-free piezoelectric ceramics were prepared by the conventional solid-state reaction method via the two-step sintering route. The effects of the content of BBiNZ on electrical properties and microstructural morphology of the LNKANbS-xBBiNZ ceramics were studied systematically. The designing of forming rhombohedral-tetragonal phase boundary in the LNKANbS-xBBiNZ system is confirmed by XRD Rietveld refinement and Raman spectroscopy, whose phase proportion is affected greatly by the BBiNZ amount. The LNKANbS-xBBiNZ ceramics exhibit complicated dielectric behavior, whose dielectric response characteristic can be fitted by the quadratic law and the Curie-Weiss law, and both having some deviation. The high-temperature conductivity of the LNKANbS-0.045BBiNZ ceramics is controlled by oxygen vacancies detected by both conductive activation energy and relaxation activation energy fitting. The LNKANbS-0.045BBiNZ ceramics exhibit excellent electrical properties, correlating with appropriate R-T phase composition proportion and improved densification and microstructural homogeneity obtained by adjusting the BBiNZ content and using the two-step sintering method. [ABSTRACT FROM AUTHOR]

0.28Pb(In1/2Nb1/2)O3-0.40Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 ceramics were synthesized by conventional solid-phase method using nano-sized In2O3. All the sintered 0.28PIN-0.40PMN-0.32PT ceramics have pure perovskite structure with composition locating at rhombohedral side around the morphotropic phase boundary (MPB) region. The 0.28PIN-0.40PMN-0.32PT ceramics belong to displacive driving ferroelectrics with apparent diffused phase transition characteristic. Although the rhombohedral-tetragonal ferroelectric phase transition temperature (TR-T) increases only to ∼120 °C due to the solid solution of Pb(In1/2Nb1/2) (PIN), the 0.28PIN-0.40PMN-0.32PT ceramics present high piezoelectric thermal stability till around the Curie temperature (Tm), which extremely widens the working temperature range and makes the 0.28PIN-0.40PMN-0.32PT ceramics suitable for high-temperature piezoelectric applications. [ABSTRACT FROM AUTHOR]

• Low-temperature sintering was realized in BCZT-xDy ceramics due to adding BCuW. • Densified morphology was due to liquid-phase sintering. • Relaxor ferroelectric characteristic was due to ion substitution and adding BCuW. • Rather large strain and low strain hysteresis at low-electric field were achieved. Ba(Cu 0.5 W 0.5)O 3 (BCuW)-doped [(Ba 0.85 Ca 0.15) 1-x Dy x ](Zr 0.1 Ti 0.9)O 3 (BCZT-xDy, x = 0.001, 0.03) ceramics were prepared by conventional ceramic processing via low-temperature sintering technique. Rather pure perovskite structure and densified morphology with irregular nearly spherical-shape grains are achieved in all ceramics due to liquid-phase sintering. All BCuW-doped BCZT-xDy ceramics present apparent dielectric frequency dispersion and relaxor ferroelectric characteristic due to ion substitution and adding BCuW. The ceramics prepared at optimized sintering temperatures have rather large strain and small strain hysteresis, showing prospect application in piezoelectric high-precision actuators. [ABSTRACT FROM AUTHOR]

Due to the urgent demands for high-Curie temperature (T C /T m) piezoelectric materials in geothermal exploration, aerospace and related fields, high-T C /T m ferroelectrics have attracted booming research attention. The high-T m 0.25Bi(Ni 1/2 Ti 1/2)O 3 -0.75 Pb(Zr 1/2 Ti 1/2)O 3 (0.25BNT-0.75PZT) ceramics were prepared by solid-state sintering method and via partial oxalate route, where the 0.25BNT-0.75PZT ceramics prepared via the partial oxalate route exhibit better electrical properties (T m = 232 °C (10 kHz), ε m = 10963, P r = 26.14 μC/cm2, E c = 15.61 kV/cm, d 33 = 521 pC/N, d 33 * = 553.3 pm/V, K p = 47.1%, and Q m = 21.6). The nano-scale domain configuration of the ceramics was revealed by piezoelectric force microscopy (PFM), and the relationship between the micro-structure and macro-electrical properties was analyzed. The ferroelectric phase transition mechanism was studied by temperature dependent Raman spectroscopy. The reduction of energy barrier of lattice distortion and polarization deflection is caused by nanometer-sized domain structure, low symmetric polar nano-regions and/or coexistence of multi-ferroelectric phases, contributing to the excellent electrical properties of the 0.25BNT-0.75PZT ceramics prepared via the partial oxalate route. • The highlights of the paper are listed as below: • The ceramics prepared via partial oxalate route exhibit better electrical properties. • Complex domains composed of island domains and strip domains are observed by PFM. • Unknown phase transition below the T C temperature is observed by Raman spectroscopy. • High piezoelectricity and phase transition characteristic mechanisms are revealed. [ABSTRACT FROM AUTHOR]