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[(Ba0.85Ca0.15)1-xDyx](Zr0.1Ti0.9)O3 (x mol% Dy-BCZT, x = 0.05, 0.2, 0.5, 1 and 3 mol%) multifunctional lead-free ceramics were prepared by traditional solid-state reaction method, where the influence of Dy doping amount and sintering condition was investigated. All sintered x mol% Dy-BCZT ceramics exhibit pure perovskite structure, large density, and high resistivity, which are affected greatly by Dy doping amount and sintering temperature. The phase structure changes from mainly tetragonal phase to pseudo-cubic phase with the increase of Dy doping amount, and presents irregular change on sintering temperature. Most samples have excellent dielectric, ferroelectric and stain, piezoelectric and fluorescent properties, which can be improved by changing Dy doping amount and tailoring sintering condition. Maximum piezoelectric-fluorescent coupling effect is obtained by selecting composition, optimizing Dy doping amount, and tailoring sintering condition due to morphotropic phase boundary effect and concentration quenching effect, which provides broad application prospect in the field of optoelectronics. [ABSTRACT FROM AUTHOR]

0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMNT) piezoelectric ceramics were prepared by traditional ceramic processing via B-site oxide mixing route and columbite precursor method using oxides as raw materials, where the influences of MgO purity, whether heat treatment of MgO and synthesis techniques were studied. When using MgO with purity of 98%, the amount of pyrochlore phase in the sintered PMNT ceramics is rather high no matter what synthesis techniques used. Phase-pure perovskite PMNT ceramics can be prepared via the columbite precursor method using 99.99% MgO as raw material after pre-heated at 1200 °C for 4 h. All the PMNT ceramics exhibit rhombohedral perovskite structure with composition approaching the morphotropic phase boundary. The ceramics' density is affected little by pyrochlore impurity, whereas the sintering temperature range is narrow and the 1245 °C sintered phase-pure PMNT ceramics have the largest relative density and compact micro-morphology. The PMNT ceramics present apparent relaxor ferroelectrics characteristic, where the samples with low content of pyrochlore phase or with phase-pure perovskite structure have excellent dielectric property. The samples present easy polarization characteristic, in which the PMNT ceramics with high purity or phase-pure perovskite phase have excellent piezoelectricity. [ABSTRACT FROM AUTHOR]

0.55 Bi(Ni0.5Ti0.5)O3–0.05BiFeO3–0.4PbTiO3 ((0.55BNT–0.05BF–0.4PT)) ceramics were prepared by low-temperature solid-phase sintering method due to adding sintering additives. The 800 °C calcined powders present relatively pure perovskite structure. The 990 °C–1030 °C sintered ceramics exhibit pure perovskite structure, and the density is increased significantly as compared with the undoped ones due to the addition of 0.5 wt% LiBO2. The "0.55BNT–0.05BF–0.4PT" samples sintered at 1010 °C have large density, compact microstructural morphology, high Curie temperature and excellent electrical properties. The ceramics show apparent relaxor ferroelectric behavior and dielectric relaxation characteristic. Grains conduction contributes mainly to the high-temperature conduction, which can be attributed to the migration of oxygen vacancies produced due to the evaporation of ions during sintering. [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]

Using composition designing, Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) ceramics with compositions around the morphotropic phase boundary (MPB) were prepared by the solid-state reaction method via the columbite and wolframite precursor techniques. X-ray diffraction (XRD) measurement and XRD peaks fitting combined with electrical performance characterization confirm the occurrence of composition-induced ferroelectric phase change, and the sintered PIN-PMN-PT ceramics present the coexistence of rhombohedral and tetragonal ferroelectric phases. Composition exerts great influence on the relative density of the sintered ceramics, and the 0.28Pb(In1/2Nb1/2)O3-0.40Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (0.28PIN-0.40PMN-0.32PT) ceramics exhibit rather uniform microstructural morphology with high relative density of 94.4%. Dielectric, ferroelectric, and piezoelectric performance characterization also confirm the existence of the MPB effects, where the composition having performance maximum presents slight difference, proving that MPB has the composition region. Dielectric response behavior fitting and Raman spectroscopy measurement confirm the PIN-PMN-PT ceramics approach normal ferroelectrics with apparent diffusive transition characteristic and the occurrence of composition-induced ferroelectric phase change. [ABSTRACT FROM AUTHOR]

High-Curie temperature (TC) piezoelectric ceramics 0.15Pb(Mg1/3Nb2/3)O3-0.38PbHfO3-0.47PbTiO3 (0.15PMN-0.38PH-0.47PT) were fabricated via the citrate method, which shows pure perovskite structure. The ceramics have composition locating at the rhombohedral side around the morphotropic phase boundary (MPB), and present enhanced electrical properties as compared with those prepared by the solid-state reaction method via the columbite precursor technique. Temperature-dependent Raman spectroscopy not only proves the occurrence of the ferroelectric to paraelectric phase transition around TC, but also detects the successive phase symmetry transitions, which correlate with the polar nanoregions (PNRs) or the coexistence of multiple ferroelectric phases. Large quantities of fine stripe nanoscale ferroelectric domains are observed by piezoresponse force microscopy (PFM) in the 0.15PMN-0.38PH-0.47PT ceramics, which form the larger micron island domains. Temperature-dependent Raman spectra and PFM results indicate that the excellent dielectric, ferroelectric and piezoelectric properties of the 0.15PMN-0.38PH-0.47PT ceramics can be attributed to either the existence of the PNRs with low symmetry or the multiple-ferroelectric-phases coexistence around room temperature and the fine stripe ferroelectric domains. [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]

(Ba0.85Ca0.15)(Hf0.10Ti0.90)O3 (BCHT) lead-free piezoelectric ceramics were synthesized via the powder injection molding process sintered at several temperatures, in which the BCHT ceramics were prepared by the conventional ceramic processing sintered at the optimized temperature 1450 °C for comparison. All the synthesized BCHT ceramics exhibit rather pure perovskite phase structure, where the BCHT ceramics prepared via the powder injection molding process present more apparent multiphases coexistence characteristic. The electrical properties of the BCHT ceramics prepared via the powder injection molding process are slightly better than those prepared by the solid-state sintering method, which correlate with the increase of ceramics densification and the change of grains micro-morphology. The powder injection molding technique provides a feasible way to synthesize irregular shaped piezoelectric ceramics with excellent electrical performance. [ABSTRACT FROM AUTHOR]

The 0.95(Li0.03Na0.5K0.47)(Nb0.92Sb0.05Ta0.03)O3-0.05(Ba0.5Ca0.5)ZrO3 (LNKNST-BCZ) lead-free piezoelectric ceramics were prepared by the conventional ceramic processing via the two-step sintering method. The phase structure purity and electrical properties of the LNKNST-BCZ ceramics can be improved further by tailoring the sintering temperature and sintering time. Rather pure perovskite structure with the coexistence of ferroelectric rhombohedral (R) and tetragonal (T) phases can be obtained in the LNKNST-BCZ ceramics via the two-step sintering method confirmed by the X-ray diffraction (XRD) analysis. Sintered at optimized conditions the LNKNST-BCZ ceramics present high densification and rather homogeneous microstructure morphology. The Curie-Weiss law and the quadratic law fitting prove that the dielectric behavior of the LNKNST-BCZ ceramics approaches closer to the normal ferroelectrics with slight diffused phase transition characteristic. The LNKNST-BCZ ceramics sintered at 1180°C for 0.5 h exhibit the optimum dielectric, ferroelectric and piezoelectric properties. The improvement of the densification and piezoelectric properties of the LNKNST-BCZ ceramics can be attributed to the polymorphic R-T phase boundary and densified microstructure morphology induced by (Ba0.5Ca0.5)ZrO3 (BCZ) doping and two-step sintering method. [ABSTRACT FROM AUTHOR]

The ferroelectric phase transition characteristics of the 0.32Pb(In1/2Nb1/2)O3-0.345Pb(Mg1/3Nb2/3)O3-0.335PbTiO3(0.32PIN-0.345PMN-0.335PT) single crystals were studied by the temperature-dependent Raman spectroscopy and some electrical properties. Ferroelectric monoclinic phase was confirmed at room temperature by the numbers of the Raman modes. Successive ferroelectric phase transitions, i.e. ferroelectric monoclinic phase to ferroelectric tetragonal phase transition (FEM-FET) and ferroelectric tetragonal phase to paraelectric cubic phase transition (FET-PC), are evidenced by the anomalies of Raman modes line width, peaks intensity and their ratios aroundTM-TandTC/Tmtemperatures. The temperature dependent permittivity derivative ξ =dϵ/dTnot only provides further evidence of the successive ferroelectric phase transitions, but also demonstrates the second-order transition characteristic of the FEM-FETphase transition and the first-order transition feature of the FET-PCphase transition. The FEM-FETphase transition is also confirmed by the abnormal narrowing of the P-E loops, decrease of thePrandEcvalues, and extremums of the pyroelectric performance. [ABSTRACT FROM PUBLISHER]

1 mol% rare-earth element doped [(Ba0.85Ca0.15)0.99Re0.01](Zr0.1Ti0.9)O3(BCZT-Re, Re = La, Sm, Yb, Eu and Er) lead-free piezoelectric ceramics were prepared by the conventional ceramic processing using high-purity carbonates and oxides as raw materials. The BCZT-Re ceramics sintered at 1450°C exhibit pure rhombohedral perovskite structure approaching the morphotropic phase boundary (MPB) composition accompanied by different relative density and grain size distribution. The dielectric behavior of the BCZT-Re ceramics approaches normal ferroelectrics but with slightly broad dielectric response peaks, and can be fitted well by the Curie-Weiss law above the Curie temperature TCbut in a limited temperature range. Besides the La doping, the other BCZT-Re ceramics present symmetric and saturated P-E hysteresis loops, in which the BCZT-Eu ceramics exhibit apparently large values of polarization remnant Prand coercive field Ec. The Prand Ecvalues decrease rapidly around 80–90°C, depending on compositions, in the BCZT-Re ceramics, determining their safe use temperatures. Excellent fluorescence performance with different photoluminescence emission intensity and light color is induced by the rare-earth doping in the BCZT-Re ceramics, which can meet the requirements of the multifunctional applications using the ferroelectric-based materials. [ABSTRACT FROM PUBLISHER]

xPb(Mg1/3Nb2/3)O3-yPbZrO3-(1-x-y)PbTiO3(PMN-PZ-PT) ferroelectric ceramics were prepared by the conventional ceramic processing via a B-site oxide mixing route. Complete solid solutions can be formed for PMN-PZ-PT in the whole composition range studied, which exhibits pure tetragonal, morphotropic phase boundary (MPB) or rhombohedral perovskite structure depending on compositions. Enhanced structure and electrical performance detected by XRD measurement, and dielectric, ferroelectric and piezoelectric properties characterization confirm the MPB effect. Such phenomena correspond well with the composition-induced successively structural change from rhombohedral, across MPB, and to tetragonal perovskite structure with the increase of the PbTiO3content. The preliminary composition phase diagram of the PMN-PZ-PT system is determined by XRD measurement combining with electrical properties characterization. The mechanisms of the structure and electrical properties enhancement are related to easy paths with flattened free energy induced by polarization rotation and polarization extension. [ABSTRACT FROM AUTHOR]

0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3(0.69PMN-0.31PT) ceramics were prepared by the solid-state reaction method via the columbite precursor route, which exhibit phase-pure perovskite structure with the morphotropic phase boundary (MPB) composition and excellent electrical properties, and are appropriate for further research. Dielectric aging behavior of the 0.69PMN-0.31PT ceramics exhibits a linear decrease dependence on the logarithm of time, proving partly its relaxor ferroelectric characteristic and correlates with microcompositional inhomogeneity. The electrical properties of the 0.69PMN-0.31PT ceramics decrease greatly above the depolarization temperature, being 120°C, whereas they exhibit excellent time stabilization. Mechanical properties of the 0.69PMN-0.31PT ceramics are improved apparently after coating Ag electrode and poling, which relate to the contributions of electrode status and domain switching. The major failure mechanism is transgranular fracture in the compression fracture samples and intergranular fracture in the bending fracture samples, respectively, determined by SEM observation. [ABSTRACT FROM PUBLISHER]

The 0.69Pb(Mg1/3Nb2/3)O3-0.31PbTiO3(0.69PMN-0.31PT) ceramics were prepared by a partial oxalate route via the columbite precursor method, a modified columbite precursor method and the B-site oxide mixing route. X-ray diffraction (XRD) measurement confirmed that pure-phase perovskite 0.69PMN-0.31PT ceramics were prepared by the modified columbite precursor method. All the sintered 0.69PMN-0.31PT ceramics exhibit large relative density, and rather homogenous and densified microstructure morphology, in which the 0.69PMN-0.31PT ceramics prepared by the modified columbite precursor method exhibit large bulk density, being 7.9015 g/cm3, which reaches 96.74% of the theoretical density. The largest value of dielectric constant maximum (ϵm) appears in the 0.69PMN-0.31PT ceramics prepared by the B-site oxide mixing route, being 32232 at 1 kHz. All the synthesized 0.69PMN-0.31PT ceramics exhibit typical ferroelectric phase transition with slightly diffused character, fully developed, saturated and symmetric P-E hysteresis loops, and excellent piezoelectric property. Ceramic processings exert great effects on electrical properties of the synthesized ceramics. Comparatively, the 0.69PMN-0.31PT ceramics prepared by the B-site oxide mixing route exhibit excellent electrical properties. [ABSTRACT FROM PUBLISHER]

Phase-pure perovskite structure (KxLa0.05-x)Ba0.95TiO3 ceramics were prepared by the conventional solid-state reaction method. With the increase of the ratio of K/La, crystal structure of the (KxLa0.05-x)Ba0.95TiO3 ceramics changes gradually from pseudo-cubic perovskite structure to tetragonal one. The sintered (KxLa0.05-x)Ba0.95TiO3 ceramics exhibit rather high relative density and rather homogenous microstructure morphology composed of submicron grains. With the decrease of the ratio of K/La, the temperature of dielectric constant maximum (TC or Tm) decreases almost linearly, and the dielectric response character of the (KxLa0.05-x)Ba0.95TiO3 ceramics changes from narrow and sharp dielectric peaks to broad and diffused ones gradually accompanied by the increase of dielectric frequency dispersion. The (KxLa0.05-x)Ba0.95TiO3 ceramics exhibit rather slim P-E hysteresis loops with slight character of asymmetry. Via adjusting the ratio of K/La, the acceptor and donor doping states are tailored, therefore, excellent ferroelectric and piezoelectric properties can be obtained in the (KxLa0.05-x)Ba0.95TiO3 ceramics. [ABSTRACT FROM PUBLISHER]

(Na1/2K1/2)NbO3 (NKN) and 0.95NKN-0.05AB (AB = CaTiO3 (CT), LiSbO3 (LS), (Ba1/2Sr1/2)TiO3 (BST)) lead-free piezoelectric ceramics were prepared by conventional solid-state reaction method. XRD measurement confirmed that the second component doped NKN ceramics exhibit pure tetragonal perovskite structure. The addition of the second component greatly increases relative density and improves electrical properties of the NKN ceramics. Especially, the 0.95NKN-0.05LS ceramics exhibit high densification, being 93.16% of the theoretical density, rather homogenous micromorphology, and excellent integral electrical properties, where the value of dielectric constant maximum εm at 1kHz is 4780, remanent polarization Pr is 19.66μC/cm2 and piezoelectric constant d33 is 194pC/N. [ABSTRACT FROM AUTHOR]