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1.
The screen-printing multilayer grain growth (MLGG) technique is successfully applied to alkaline niobate lead-free piezoelectric ceramics. Highly textured (K0.5Na0.5)NbO3 (KNN) ceramics with 〈0 0 1〉 orientation (f = 93%) were fabricated by MLGG technique with plate-like NaNbO3 templates. The influence of sintering temperature on grain orientation and microstructure was studied. The textured KNN ceramics showed very high piezoelectric constant d33 = 133 pC/N, and high electromechanical coupling factor kp = 0.54. These properties were superior to those of conventional randomly oriented ceramics, and reach the level of those of textured KNN ceramic prepared by tape-casting technique. Compared with other grain orientation techniques, screen-printing is a simple, inexpensive and effective method to fabricate grain oriented lead-free piezoelectric ceramics. 相似文献
2.
Lead-free ceramics (1 ? x)(K0.48Na0.52)NbO3–(x/5.15)K2.9Li1.95Nb5.15O15.3 (x = 0.3–0.6, KNN–KLN100x) were prepared by conventional sintering technique at a low temperature of 960 °C. The effects of KLN contents on microstructure, dielectric, and piezoelectric properties were investigated. After the addition of KLN, the sintering performance and Curie temperature of the ceramics were markedly improved. The ceramics with x = 0.3 exhibited very good piezoelectric properties: d33 = 138 pC/N, kp = 45.03%, Tc = 495 °C, the dielectric constant at room temperature ?r (RT) = 478 and the maximum dielectric constant ?r (max) = 5067. These results indicated that the KNN–KLN100x lead-free ceramics sintered at low temperatures are promising for high temperature piezoelectric applications. 相似文献
3.
The effects of calcination temperature on the bulk density, piezoelectric, and ferroelectric properties were investigated for the Ag2O doped 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 ceramics. The calcination temperatures were varied from 750 to 950 °C by 50 °C differences. An tetragonal XRD pattern, consistent with single-phase 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 was obtained after calcination at 850 °C for 2 h. And the experimental results showed that Ag2O doped 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 ceramics calcined at 850 °C had a remnant polarization Pr=24.5 μC/cm2, bulk density=4.32 g/cm3, piezoelectric constant d33=282 pC/N and electromechanical coefficient kp=37.8%. 相似文献
4.
Dunmin Lin Qiaoji Zheng Ying Li Yang Wan Qiang Li Wei Zhou 《Journal of the European Ceramic Society》2013,33(15-16):3023-3036
The effects of composition, sintering temperature and dwell time on the microstructure and electrical properties of (0.75 ? x)BiFeO3–0.25BaTiO3–xBi0.5K0.5TiO3 + 1 mol% MnO2 ceramics were studied. The ceramics sintered at 1000 °C for 2 h possess a pure perovskite structure and a morphotropic phase boundary of rhombohedral and pseudocubic phases is formed at x = 0.025. The addition of Bi0.5K0.5TiO3 retards the grain growth and induces two dielectric anomalies at high temperatures (T1 ~ 450–550 °C and T2 ~ 700 °C, respectively). After the addition of 2.5 mol% Bi0.5K0.5TiO3, the ferroelectric and piezoelectric properties of the ceramics are improved and very high Curie temperature of 708 °C is obtained. Sintering temperature has an important influence on the microstructure and electrical properties of the ceramics. Critical sintering temperature is 970 °C. For the ceramic with x = 0.025 sintered at/above 970 °C, large grains, good densification, high resistivity and enhanced electrical properties are obtained. The weak dependences of microstructure and electrical properties on dwell time are observed for the ceramic with x = 0.025. 相似文献
5.
《Ceramics International》2016,42(3):4274-4284
Bi0.5(Na0.65K0.35)0.5TiO3 (BNKT) and Mn-modified Bi0.5(Na0.65K0.35)0.5(MnxTi1−x)O3 (BNKMT-103x), (x=0.0–0.5%) ferroelectric ceramics were synthesized by solid-state reaction method. Optimization of calcination temperature in Mn-doped ceramics was carried out for the removal of secondary phases observed in XRD analysis. BNKMT ceramics sintered at 1090 °C showed enhanced dielectric, piezoelectric and ferroelectric properties in comparison to pure BNKT. The average grain size was found to increase from 0.35 μm in BNKT to 0.52 μm in Bi0.5(Na0.65K0.35)0.5(Mn0.0025Ti0.9975)O3 (BNKMT-2.5) ceramics. The dielectric permittivity maximum temperature (Tm) was increased to a maximum of 345 °C with Mn-modification. AC conductivity analysis was performed as a function of temperature and frequency to investigate the conduction behavior and determine activation energies. Significant high value of piezoelectric charge coefficient (d33=176 pC/N) was achieved in BNKMT 2.5 ceramics. Improved temperature stability of ferroelectric behavior was observed in the temperature dependent P–E hysteresis loops as a result of Mn-incorporation. The fatigue free nature along with enhanced dielectric and ferroelectric properties make BNKMT-2.5 ceramic a promising candidate for replacing lead based ceramics in device applications. 相似文献
6.
《Ceramics International》2016,42(14):15664-15670
Sodium bismuth titanate (BNT) nanopowder of molar composition 50/50 (Na0.5Bi0.5TiO3) was prepared by a sol-gel processing method. The structure and microstructure of the precursor gel as well as the ferroelectric, pyroelectric, dielectric and piezoelectric properties of the BNT were studied. BNT crystallized in the rhombohedra perovskites structure Na0.5Bi0.5TiO3 was obtained from the precursor gel by heating at 700 °C for 2 h in air. The BNT ceramic at 1100 °C sintering temperature present high crystallinity, good dielectric properties at 1 kHz (ε′=885, tan δ=0.03, Tc=370 °C), piezoelectric properties (k33=0.39, c33=105 GPa, e33=12.6 C/m2, d33=120 pC/N), high remnant polarization (Pr=47 μC/cm2) and pyroelectric coefficient (=707 μC/m2 K) and low coercive field (Ec=55 kV/cm). Hence, the BNT prepared by sol-gel method could be used for silicon based memory device application where a low synthesis temperature is a key requirement. 相似文献
7.
Li2CO3 has been used as a sintering aid for fabricating lead-free ferroelectric ceramic 0.93(Bi0.5Na0.5TiO3)-0.07BaTiO3. A small amount (0.5 wt%) of it can effectively lower the sintering temperature of the ceramic from 1200 °C to 980 °C. Unlike other low temperature-sintered ferroelectric ceramics, the ceramic retains its good dielectric and piezoelectric properties, giving a high dielectric constant (1570), low dielectric loss (4.8%) and large piezoelectric coefficient (180 pC/N). The “depolarization” temperature is also increased to 100 °C and the thermal stability of piezoelectricity is improved. Our results reveal that oxygen vacancies generated from the diffusion of the sintering aid into the lattices are crucial for realizing the low temperature sintering. Owing to the low sintering temperature and good dielectric and piezoelectric properties, the ceramics, especially of multilayered structure, should have great potential for practical applications. 相似文献
8.
《Ceramics International》2016,42(13):14999-15004
Unfilled tungsten bronze ceramics with a composition of Ba4SmFe0.5Nb9.5O30 were prepared by the conventional solid-state sintering method. The phase, microstructure, dielectric and ferroelectric properties were studied. Room temperature XRD results indicated that the ceramic occurs in the tetragonal space group P4bm phase with cell parameters of a=b=12.4712(2) Å and c=3.9430(2) Å. The temperature-dependent dielectric properties, XRD data and Raman spectra data indicated that BSFN ceramics exhibit no phase changes from 35 °C to 450 °C. Fitting of a Vogel-Fulcher relationship with an activated energy Ea of 0.11 eV indicates an unambiguous dielectric relaxor state near room temperature. Furthermore, the BSFN ceramics exhibited residual polarization and coercive field of 3.45 µC/cm2 and 24.65 kV/cm, respectively. 相似文献
9.
《Journal of the European Ceramic Society》2006,26(15):3247-3251
Lead-free [Bi1−y(Na1−x−yLix)]0.5BayTiO3 (BNLB-x/y) piezoelectric ceramics were prepared by sintering the constituent oxides, and their piezoelectric and ferroelectric properties studied. The results of X-ray diffraction (XRD) suggest that Li+ and Ba2+ diffuse into the Bi0.5Na0.5TiO3 (BNT) lattices to form a solid solution with a single-phase perovskite structure. The ceramics can be well sintered at 1100–1150 °C. The introduction of Li+ and Ba2+ into Bi0.5Na0.5TiO3 significantly decreases the coercive field, Ec but maintains the large remanent polarization, Pr of the materials. The ceramics exhibit relatively good piezoelectric properties and very strong ferroelectricity: piezoelectric constant, d33 = 208 pC/N, planar electromechanical coupling factor, kp = 37.0%, remanent polarization, Pr = 38.5 μC/cm2, coercive field, Ec = 3.27 kV/mm. The depolarization temperature, Td of BNLB-0.075/0.04 ceramics is about 190 °C. 相似文献
10.
Microstructure and piezoelectric properties of textured (Na0.84K0.16)0.5Bi0.5TiO3 lead-free ceramics
《Journal of the European Ceramic Society》2007,27(12):3453-3458
Textured (Na,K)0.5Bi0.5TiO3 ceramics were fabricated by reactive-templated grain growth in combination with tape casting. The effects of sintering conditions on the grain orientation and the piezoelectric properties of the textured (Na,K)0.5Bi0.5TiO3 ceramics were investigated. The results show that the textured ceramics have microstructure with plated-like grains aligning in the direction parallel to the casting plane. The ceramics exhibit {h 0 0} preferred orientation and the degree of orientation is larger than 0.7. The degree of grain orientation increases with the increasing sintering temperature. The textured ceramics show anisotropy dielectric and piezoelectric properties in the directions of parallel and perpendicular to the casting plane. The ceramics in the perpendicular direction exhibit better dielectric and piezoelectric properties than those of the nontextured ceramics with the same composition. The optimized sintering temperature is 1150 °C where the maximum d33 of 134 pC/N parallel to casting plane, the maximum k31 of 0.31, and the maximum Qm of 154 in perpendicular direction were obtained. 相似文献
11.
《Ceramics International》2016,42(9):10619-10623
Lead-free piezoelectric ceramics, Sr1−x(K0.5Bi0.5)xBi2Nb2O9 (SKBN-x, x=0, 0.2, 0.5, 1.0), were synthesized by a conventional solid-state reaction. Structural and electrical properties of SKBN-x ceramics were investigated. X-ray diffraction analysis suggested that the substitution led to the formation of a layered perovskite structure. Plate-like morphologies for the grains were clearly observed in all the samples, which are characteristic for layer-structure Aurivillius compounds. The Curie temperature (Tc) is found to shift to higher temperature from 445 °C to 509 °C with increasing (K, Bi) content. Excellent remanent polarization (2Pr∼15 μC/cm2) were obtained for SKBN-0.2 ceramic. High piezoelectric coefficient of d33∼21 pC/N were obtained for the samples at x=0.5. Additionally, thermal annealing studies indicated that the piezoelectric coefficient (d33) of SKBN-0.5 was unchanged even if annealing temperature increased to be 450 °C, demonstrating the ceramics are the promising candidates for high-temperature applications. 相似文献
12.
Nam Binh Do Hyun Deok Jang Inki Hong Hyoung Su Han Duc Thang Le Weon Pil Tai Jae Shin Lee 《Ceramics International》2012
Effect of excess CuO additive on the sintering behavior and piezoelectric properties of Bi0.5(Na82K0.18)0.5TiO3 ceramics was investigated. The addition of small amount of excess CuO as low as 1 mol% was quite effective to lower the sintering temperature (Ts) of BNKT ceramics down to 975 °C while their piezoelectric properties were degraded by Cu doping. However, the electric field-induced strain was markedly enhanced by further addition of Nb2O5 with CuO without elevating Ts. The normalized strain Smax/Emax of 427 pm/V was obtained with a specimen sintered with 0.02 mol CuO and 0.03 mol Nb2O5 in excess. 相似文献
13.
14.
Ali Hussain Chang Won Ahn Aman Ullah Jae Shin Lee Ill Won Kim 《Ceramics International》2012,38(5):4143-4149
Lead-free piezoelectric (1 ? x)Bi0.5(Na0.78K0.22)0.5TiO3–xK0.5Na0.5NbO3 (BNKT–xKNN, x = 0–0.10) ceramics were synthesized using a conventional, solid-state reaction method. The effect of KNN addition on BNKT ceramics was investigated through X-ray diffraction (XRD), dielectric, ferroelectric and electric field-induced strain characterizations. XRD revealed a pure perovskite phase with tetragonal symmetry in the studied composition range. As the KNN content increased, the depolarization temperature (Td) as well as maximum dielectric constant (?m) decreased. The addition of KNN destabilized the ferroelectric order of BNKT ceramics exhibiting a pinched-type hysteresis loop with low remnant polarization (11 μC/cm2) and small piezoelectric constant (27 pC/N) at 3 mol% KNN. As a result, at x = 0.03 a significant enhancement of 0.22% was observed in the electric field-induced strain, which corresponds to a normalized strain (Smax/Emax) of ~434 pm/V. This enhancement is attributed to the coexistence of ferroelectric and non-polar phases at room temperature. 相似文献
15.
《Ceramics International》2015,41(8):9555-9559
A second calcination–milling step was introduced in the conventional processing of (K, Na)0.5NbO3 (KNN) ceramics (sintered in air) to further homogenenize the particle size distribution of the pre-sintered powders. The ceramic derived from the powders prepared by the two-step route possesses grains with better uniformity and is more compact. The relative density of the bulk ceramic reached 96.9%. Excellent properties are obtained in as-prepared KNN ceramics with kp=44%, d33=111 pC/N, tanδ=0.85%, ε33T/εo=311, Qm=193, Pr=25.4 μC/cm2, d33⁎=251 pm/V, which are superior to those of the ceramics derived from the powders calcined once as used in the traditional processing. These results indicate that twice-calcination–milling route is shown to be a facile and effective way to simultaneously improve the piezoelectric and ferroelectric properties of KNN ceramics without sintering aids. 相似文献
16.
《Journal of the European Ceramic Society》2007,27(13-15):3613-3617
This study investigated the influence of strontium doping on both the sintering behavior and the piezoelectric properties of PNZT–PNN ceramics. The piezoelectric ceramics was produced by solid state reaction between metallic oxides, strontium carbonates (SrCO3) and oxides precursors. NiNb2O6 precursors were mixed with the oxides to avoid the large-scale formation of pyrochlore phases during the sintering process and to favor the formation of the perovskite structure. Sintering experiments were accomplished between 900 °C and 1100 °C for PNZT–PNN with 0–4 mol% strontium. Dilatometer curves indicated that the densification of these samples occurs by 850 °C and the electromechanical characterization showed that strontium doping enhances the soft piezoelectric properties of the PZT–PNN ceramics.Consequently, a sintering temperature of 900 °C is sufficient to obtain doped PZT–PNN tablets with 99% of the theoretical density and excellent soft piezoelectric properties (ɛr > 4000; Kp > 60; d33 > 1000 pm/V). This makes those ceramics suitable for the construction of high efficiency actuators with low sintering temperature. The low Curie temperature is the only drawback of this material for some applications such as engine fuel injection. 相似文献
17.
《Journal of the European Ceramic Society》2017,37(5):2091-2097
Systematic investigation on phase transition, dielectric and piezoelectric properties of (1-x)K0.5Na0.5Nb0.997Cu0.0075O3-xSrZrO3 (x = 0, 0.03, 0.06, 0.09, 0.12, 0.15, abbreviated as KNNC-100xSZ) ceramics was carried out. Due to the coexistence of orthorhombic and tetragonal phase in a wide temperature range, a diffused polymorphic phase transition (PPT) region was achieved in KNNC with x ≥ 0.06. KNNC-12SZ ceramics exhibited high dielectric permittivity (∼1679), low dielectric loss (∼0.02) and small variation (Δe'/ε'25 °C ≤ 15%) in dielectric permittivity from −78 °C to 237.3 °C. KNNC-6SZ ceramic possessed a high level of unipolar strain (∼0.15%) and maintained a smaller variation of ±12% under the corresponding electric field of 60 kV cm−1 at 10 Hz from 25 °C to 175 °C. d33*, which was calculated according to the unipolar strain at 60 kV cm−1, was 230 pm V−1 and remained stable below 100 °C. Therefore, our work provided a new promising candidate for temperature-insensitive capacitors and piezoelectric actuators. 相似文献
18.
Microwave dielectric properties of low loss microwave dielectric ceramics: A0.5Ti0.5NbO4 (A = Zn,Co)
《Journal of the European Ceramic Society》2014,34(15):3641-3648
The microwave dielectric properties of low-loss A0.5Ti0.5NbO4 (A = Zn, Co) ceramics prepared by the solid-state route had been investigated. The influence of various sintering conditions on microwave dielectric properties and the structure for A0.5Ti0.5NbO4 (A = Zn, Co) ceramics were discussed systematically. The Zn0.5Ti0.5NbO4 ceramic (hereafter referred to as ZTN) showed the excellent dielectric properties, with ɛr = 37.4, Q × f = 194,000 (GHz), and τf = −58 ppm/°C and Co0.5Ti0.5NbO4 ceramic (hereafter referred to as CTN) had ɛr = 64, Q × f = 65,300 (GHz), and τf = 223.2 ppm/°C as sintered individually at 1100 and 1120 °C for 6 h. The dielectric constant was dependent on the ionic polarizability. The Q × f and τf are related to the packing fraction and oxygen bond valence of the compounds. Considering the extremely low dielectric loss, A0.5Ti0.5NbO4 (A = Zn and Co) ceramics could be good candidates for microwave or millimeter wave device application. 相似文献
19.
《Ceramics International》2015,41(4):5492-5497
The Aurivillius-type bismuth layer-structured ferroelectrics (BLSFs) sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15, NLBT) polycrystalline ceramics with 0.0–0.4 wt% MnO2 were synthesized using conventional solid-state processing. Phase analyses were performed by X-ray powder diffraction (XRPD), and the microstructural morphology was assessed by scanning electron microscopy (SEM). The dielectric and piezoelectric properties of the manganese-modified NLBT ceramics were investigated in detail. The results show that manganese is very effective in promoting the piezoelectric activities of NLBT ceramics, and the reasons for piezoelectric activities enhancement by manganese modification are explained. The NLBT ceramics modified with 0.2 wt% MnO2 (NLBT-Mn2) possess good piezoelectric properties, with a piezoelectric coefficient d33 of 28 pC/N. This value is the highest value among the modified NLBT-based piezoelectric ceramics examined. The temperature-dependent dielectric spectra show that the Curie temperature Tc of the manganese-modified NLBT ceramics is slightly higher than that of the pure NLBT ceramics. Thermal annealing analysis revealed that the manganese-modified NLBT ceramics possess good thermal stabilities up to 500 °C. These results demonstrate that the manganese-modified NLBT ceramics are promising materials for high temperature piezoelectric applications. 相似文献
20.
《Journal of the European Ceramic Society》2007,27(1):261-265
The effect of B2O3 addition on the sintering, microstructure and the microwave dielectric properties of LiNb0.6Ti0.5O3 ceramics have been investigated. It is found that low-level doping of B2O3 (≤2 wt.%) can significantly improve the densification and dielectric properties of LiNb0.6Ti0.5O3 ceramics. Due to the liquid phase effect of B2O3 addition, LiNb0.6Ti0.5O3 ceramics could be sintered to a theoretical density higher than 95% even at 880 °C. No secondary phase was observed for the B2O3-doped ceramics. There is no obvious degradation in dielectric properties for the ceramics with B2O3 additions. In the case of 1 wt.% B2O3 addition, the ceramics sintered at 880 °C show good microwave dielectric properties of ɛr = 70, Q × f = 5400 GHz, τf = −6.39 ppm/°C. It represents that the ceramics could be promising for multilayer low-temperature co-fired ceramics (LTCC) applications. 相似文献