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Pseudocubic-based polymorphic phase boundary structures and their effect on the piezoelectric properties of (Li,Na,K)(Nb,Sb)O3-SrZrO3 lead-free ceramics
摘要： CuO-added 0.96(LixNa0.5-xK0.5)(Nb1-ySby)O3-0.04SrZrO3 ceramics were sintered at 1020oC for 6 h. Various crystal structures were synthesized in these specimens by controlling the Li2CO3 (x) and Sb2O5 (y) contents: pseudocubic, orthorhombic-pseudocubic polymorphic phase boundary (PPB), tetragonal-pseudocubic PPB, orthorhombic-tetragonal-pseudocubic PPB, and orthorhombic-tetragonal PPB structures. The pseudocubic structure developed in these specimens was similar to the R3m rhombohedral structure instead of the Pm3m cubic structure because the specimens with a pure pseudocubic structure showed good ferroelectric and piezoelectric properties. The piezoelectric properties of the specimens were influenced by their crystal structures. The specimen with the tetragonal-pseudocubic PPB structure showed the best piezoelectric properties because this structure was similar to the tetragonal-rhombohedral morphotropic phase boundary structure developed in Pb(Zr1-xTix)O3-based ceramics. In particular, the specimen with the tetragonal-pseudocubic PPB structure corresponding to x = 0.05 and y = 0.065 showed the largest d33 and kp values of 431 pC/N and 0.43, respectively.
关键词： K)(Nb,Piezoelectric properties,Polymorphic phase boundary structure,Sb)O3-SrZrO3-based lead free piezoelectric ceramics,Pseudocubic structure,Na,(Li
更新于2025-09-23 15:23:52
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Enhanced piezoelectric properties and temperature stability of Bi4Ti3O12-based Aurivillius ceramics via W/Nb substitution
摘要： This work provides an effective method of inducing structure distortion, relieving the tetragonal strain of the TiO6 octahedron and decreasing the concentration of oxygen vacancies to improve the piezoelectricity and temperature stability of BIT ceramics. Bi4Ti2.98W0.01Nb0.01O12 possesses an optimum piezoelectric coefficient (d33) of 32 pC/N, a high Tc of 655 °C and a large resistivity of 3 × 106 Ω·cm at 500 °C. The maximum d33 reported here is approximately quadruple than that of pure BIT (~7 pC/N). Moreover, the d33 of W/Nb co-doped BIT and the in-situ temperature stability of the compression-mode sensor present a highly stable characteristic in the range of 25–600 °C. These results imply that W/Nb-modified BIT ceramics is a promising candidate for application at high temperatures of up to 600 °C.
关键词： Bi4Ti3O12,Structure distortion,Piezoelectric properties,Oxygen vacancy,Temperature stability
更新于2025-09-23 15:23:52
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Temperature-Dependent Phase Transition in Orthorhombic [011]c Pb(Mg1/3Nb2/3) O3-0.35PbTiO3 Single Crystal
摘要： Relaxor [011]c PMN-0.35PT single crystal phase transition characteristics are investigated through various methods including variable temperature dielectric properties, X-ray diffraction, bipolar ferroelectric hysteresis loops (P-E) and electric-field-induced strain (S-E) hysteresis loops measurements. The results reveal that two phase transitions exist within the range from room temperature to 250 °C: orthorhombic (O)-tetragonal (T)-cubic (C). The O-to-T and T-to-C phase transition temperatures have been identified as 84 °C and 152 °C, respectively. Diffuseness degree of the T-to-C phase transition for the unpoled single crystal has been calculated to be 1.56, implying an intermediate state between normal and relaxor ferroelectrics. Temperature-dependent remanent polarization (Pr), coercive field (Ec), saturation polarization (Ps), hysteresis loop squareness (Rsq), and longitudinal piezoelectric constant (d*33) are also explored to learn the details of the phase transitions. Variable temperature unipolar Suni-E hysteresis loops avail additional evidence for the microstructure change in the as-measured single crystal.
关键词： temperature-dependent phase transition,S-E hysteresis loops,P-E hysteresis loops,orthorhombic [011]c PMN-0.35PT,dielectric properties,piezoelectric properties
更新于2025-09-23 15:22:29
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Dielectric and piezoelectric properties of Sm3+ doped lead barium niobate (PBN) ceramics
摘要： Rhombohedral samarium doped Lead based ceramic materials were fabricated by a high temperature conventional solid state mixed oxide ceramic process. The ceramic composition Pb1-x-3y/2Bax Re3+ y Nb2O6 (x = 0.35 and y=0.00, 0.02, 0.04 and 0.06, Re3+ = Sm3+). The pure and Sm3+ doped lead barium niobate ceramic materials are single phase with rhombohedral(hexagonal) symmetry obtained from powder x-ray diffraction (XRD). The grain size has been measured for all the compositions and lying between 1.60-2.90μm. Broad dielectric peak phase transitions observed with temperature in pure and Sm3+ ion modified lead barium niobate ceramic materials. It is observed that the high values of piezoelectric charge coefficients in d31 and d33 in Sm3+ doped lead barium niobate ceramics. The mechanical quality factor Qm and d33 increases with increase of Sm3+ ion concentration and indicating a highly polarisable lead ion contributing to high Curie temperature dielectric constant.
关键词： SEM,Piezoelectric properties,Rhombohedral,Synthesis of ceramic compositions,dielectric,X-Ray diffraction
更新于2025-09-23 15:21:21
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Defect-relevant piezoelectric and ferroelectric properties in LiCuTa3O9-doped K0.5Na0.5NbO3 lead-free piezoceramics
摘要： Lead-free K0.5Na0.5NbO3 + x mol LiCuTa3O9 (abbreviated to KNN-xLCT) piezoceramics are synthesized via a conventional sintering technique. All ceramics exhibit perovskite structure and their densification is improved after the addition of LCT. The doping of small quantities of LCT (x ≤ 0.015) results in the generation of two sorts of defect complexes [i.e., ?? V??(Cu???o ) ], inducing greatly hardening electrical behaviors with high mechanical quality factor Qm of ~ 780 at x = 0.015. However, excess LCT (x ≥ 0.015) contributes to the substantial reduction of defect complexes, and thus the ceramics are softened, presenting a relatively low Qm of ~ 480 at x = 0.03. It is noted that the ceramics with x = 0.03 remain comparatively great piezoelectric performances: d33 = 96 pC/N and kp = 37%. Our study indicates that the electrical properties of KNN-based ceramics doped with LCT are closely related with microscopic defect structure in the materials.
关键词： Lead-free piezoceramics,K0.5Na0.5NbO3,Piezoelectric properties,Defect complexes,LiCuTa3O9
更新于2025-09-23 15:19:57
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Grain boundary effects on piezoelectric properties of the core–shell-structured BaTiO <sub/>3</sub> @TiO <sub/>2</sub> ceramics
摘要： Grain boundary effect on BaTiO3 has been widely investigated for several decades. However, all of them tailored the grain boundary by grain size of BaTiO3. In this case, a direct way was introduced to modify the grain boundary by coating technique to investigate the role of grain boundary in ferroelectric materials. Nonferroelectric phase TiO2 was employed to investigate grain boundary effects on the electrical properties of BaTiO3 piezoelectric ceramics. TiO2 coating can result in the reduction of piezoelectric and ferroelectric properties and the annealing process in oxygen can increase piezoelectric behavior of pure BaTiO3 due to valence state of Ti ions while that remains for Ti-modified composition possibly due to the increased grain boundary effect by impedance analysis. Compared with ferroelectric grain, grain boundary plays a critical role to impact the electrical properties of perovskite-type ferroelectric materials.
关键词： defects.,Piezoelectric properties,ferroelectric properties,BaTiO3 and titanates
更新于2025-09-19 17:15:36
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Piezoelectric and Dielectric Properties of ((K0.475Na0.495Li0.03)NbO3-0.003ZrO2)/PVDF Composites
摘要： The (K0.475Na0.495Li0.03) NbO3-0.003ZrO2 (KNNL-Z) ceramic was synthesized by the conventional solid-state reaction and (KNNL-Z)/PVDF composites were fabricated by hot-pressing process using polyvinylidene fluoride (PVDF) and KNNL-Z ceramic. The effects of the ceramic content on the crystalline structures, morphology, densities, dielectric and piezoelectric properties of (KNNL-Z)/PVDF 0–3 composites were systemically studied. The KNNL-Z ceramic possesses a perovskite phase with orthorhombic symmetry and the PVDF polymer mainly possesses a, b and c phases. Interestingly, the incorporation of the ceramic particles can decrease the crystallite size of the PVDF matrix. In addition, the b phase content increases and the a phase decreases when the ceramic particles are added. When the ceramic content increases from 40 wt.% to 80 wt.%, the relative fraction of b phase increases from 47.7% to 53.8%. Successful incorporation of ZrO2 into the KNN ceramic has been demonstrated by energy-dispersive x-ray spectroscopy and the most elements are homogeneously distributed in the composites. The dielectric and piezoelectric properties are found to be improved with the increase of KNNL-Z content. When 80 wt.% KNNL-Z is added, the dielectric permittivity reaches the value of 272 (100 Hz) at room temperature and the piezoelectric coefficient is 39 pC/N. After 30 days of aging, it is obvious that all the composites present a good stability of their piezoelectric property.
关键词： PVDF,0–3 composite,KNNL-Z,dielectric properties,piezoelectric properties
更新于2025-09-19 17:15:36
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Electromechanical Properties of Ferroelectric (NaKLi)(NbTa)O <sub/>3</sub> –CaZrO <sub/>3</sub> Ceramics
摘要： Electromechanical Properties of Ferroelectric (NaKLi)(NbTa)O3–CaZrO3 Ceramics. The effect of CaZrO3 to electric and mechanical properties of (Na0.47K0.51Li0.02)(Nb0.8Ta0.2)O3 was investigated. With increment of CaZrO3, the crystal structure of (Na0.47K0.51Li0.02)(Nb0.8Ta0.2)O3 changed from the mixture of ferroelectric orthorhombic and rhombohedral phases to paraelectric pseudo-cubic phase. On the way of transition from ferroelectric to paraelectric phases, the composition range showing the mixture of ferroelectric/paraelectric phases with a structure of core/shell was revealed with an advent of relatively large strain behavior. The shell phase formed via solid-state diffusion of Nb, Ta, Na, K ions between (Na0.47K0.51Li0.02)(Nb0.8Ta0.2)O3 and CaZrO3 particles, followed by its subsequent solution process with mixing a Ta-rich perovskite with Ca and Zr ions. In contrast, the core phase formed via a solution-precipitation process, resulting in a Ta-depleted ferroelectric perovskite. Energy-dispersive X-ray analysis showed that core was a Nb-rich ferroelectric phase and the shell was a Ta-rich paraelectric phase with Ca and Zr ions at room temperature. This structure implies an interaction between straining behaviors in the core and shell phases under an electric field, leading large deformation in macro-scale.
关键词： Piezoelectric Properties,Electrostrain,(NaKLi)(NbTa)O3,CaZrO3,Ferroelectric Material
更新于2025-09-19 17:15:36
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Origin of enhanced piezoelectric properties revealed through electric field driven studies in 0.94(Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3</sub> )a??0.06(Ba <sub/>0.85</sub> Ca <sub/>0.15</sub> Ti <sub/>0.9</sub> Zr <sub/>0.1</sub> O <sub/>3</sub> ) ceramics
摘要： A single phase 0.94(Na0.5Bi0.5TiO3)–0.06(Ba0.85Ca0.15Ti0.9Zr0.1O3) solid solution (i.e., BCZT-0.06) is prepared using a conventional solid-state sintering route with enhanced piezo and ferroelectric properties as compared to Na0.5Bi0.5TiO3 (NBT). In the context of understanding the origin of enhanced piezoelectric properties in a BCZT-0.06 specimen, electric field driven studies on different length scales, viz., global, local, and electronic structure, are carried out using x-ray/neutron diffraction, Raman scattering, and UV–Vis spectroscopic techniques. An analysis on different length scales of the electric field-driven BCZT-0.06 specimen displays minimum rhombohedral lattice distortion (δ r), reduced homogeneous lattice strain (δ), octahedral strain (ζ), and pronounced Ti-cation displacement along the polar [111] direction as compared to parent NBT. The enhanced ferro and piezoelectric responses observed in the BCZT-0.06 specimen have been attributed to the ease of non-180° domain re-orientation, domain switching, and domain wall motion due to reduced strain coupled with a polarization extension mechanism.
关键词： ferroelectric properties,electric field driven studies,solid solution,domain re-orientation,piezoelectric properties
更新于2025-09-19 17:13:59
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Enhanced dielectric and piezoelectric properties in the [001]-poled 0.25Pb(In <sub/>1/2</sub> Nb <sub/>1/2</sub> )O <sub/>3</sub> -0.43Pb(Mg <sub/>1/3</sub> Nb <sub/>2/3</sub> )O <sub/>3</sub> -0.32PbTiO <sub/>3</sub> single crystal near morphotropic phase boundary by alternating current treatment
摘要： In this paper, temperature dependance of induced dielectric and piezoelectric properties in the [001]-oriented predirect current poling (DCP) of the 0.25Pb(In1/2Nb1/2)O3-0.43Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (0.25PIN-0.43PMN-0.32PT) single crystals near morphotropic phase boundary was investigated using the alternating current treatment (ACT). By the optimized ACT conditions of 1 kV/mm at 50 Hz over 20 cycles, the dielectric permittivity (ε0) and piezoelectric coefficient (d33) at room temperature of the DCP-ACT crystal were improved to be 7120 and 2610 pC/N, which were 48% and 54% higher than that of the DCP crystal (ε0 = 4800, d33 = 1700 pC/N). Based on the temperature dependence of dielectric permittivity and dielectric loss of the DCP-ACT crystal, the induced monoclinic phases (MA and MC) were involved in the phase transition process from a rhombohedral phase to a tetragonal phase. The phase transition temperatures TR-MA of 116 °C of the DCP-ACT crystal showed about 10 °C higher than that of DCP. Meanwhile, ε0 of the DCP-ACT crystal at TR-MA and in the tetragonal phase region, at around 110 °C and 130 °C, were 160% and 390% higher than those of the DCP crystal, respectively. The ultrahigh ε0 = 17 000 of the DCP-ACT crystal at 130 °C may relate to the nanoscale heterogeneous polar-regions induced by ACT. The ACT is a promising way to enhance the dielectric and piezoelectric performance of the pre-DCP 0.25PIN-0.43PMN-0.32PT single crystals with broadened temperature range for device applications.
关键词： single crystal,piezoelectric properties,morphotropic phase boundary,alternating current treatment,dielectric properties
更新于2025-09-19 17:13:59