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1.
We studied sintering temperature to enhance the piezoelectric and dielectric properties of 0.98(Na0.5?K0.5)NbO3-0.02Li(Sb0.17Ta0.83)O3?+?0.01wt%ZnO (hereafter NKN-LST+ZnO) lead free piezoelectric ceramics. The synthesis and sintering method were the conventional ceramic technique and sintering was executed at 1080?~?1120°C. We found that optimal sintering temperature and NKN-LST+ZnO ceramics showed the highest piezoelectric properties and dielectric properties at the optimal sintering temperature. The NKN-LST+ZnO ceramics sintered at 1090°C show a superior performance with piezoelectric constant d 33?=?185 pC/N, k p?=?0.36, ε 33 T 0?=?491 respectively. These results reveal that NKN-LST+ZnO ceramics are promising candidate materials for lead-free piezoelectric application.  相似文献   

2.
0.94(K05Na0.5)NbO3?0.03LiNbO3?0.03LiSbO3 (KNLNS) lead-free piezoelectric ceramics were prepared by conventional mixed oxide route with normal sintering method. The samples were sintered at different temperatures with KNLNS powder atmosphere to prevent volatilization of alkali metal oxides at high temperature. The effects of sintering temperature on the density, structure and electric properties of KNLNS ceramics were studied. X-ray diffraction (XRD) results showed that the crystal structure of the crushed KNLNS ceramic powders were pure perovskite phase with tetragonal phase structure when sintered at T????1080°C. However a K3Li2Nb5O15 phase with tetragonal tungsten bronze structure began to appear when the sintering temperature was higher than 1080°C. The optimum sintering temperature was 1080°C which was determined by measuring the density of the samples. Scanning electron microscope (SEM) observation indicated that the sintering temperature had a great effect on the microstructure of the samples. The KNLNS ceramics under the optimum sintering temperature showed excellent electric properties: ???=?4.29 g/cm3, ?? r?=?826, tan???=?0.049, d 33?=?190 pC/N, k p?=?0.30, and T c?=?385°C. The results show that the KNLNS ceramics are promising candidate for lead-free piezoelectric ceramics.  相似文献   

3.
Phase structure, microstructure, piezoelectric and dielectric properties of the 0.4 wt% Ce doped 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (Ce-BNT6BT) ceramics sintered at different temperatures have been investigated. The powder X-ray diffraction patterns showed that all of the Ce-BNT6BT ceramics exhibited a single perovskite structure with the co-existence of the rhombohedral and tetragonal phase. The morphologies of inside and outside of the bulk indicated that the different sintering temperatures did not cause the second phase on the inside of bulk. However, the TiO2 existed on the outside of the bulk due to the Bi2O3 and Na2O volatilizing at higher temperature. The ceramics sintered at 1,200 °C showed a relatively large remnant polarization (P r) of about 34.2 μC/cm2, and a coercive field (E c) of about 22.6 kV/cm at room temperature. The permittivity ? r of the ceramics increased with the increasing of sintering temperature in antiferroelectric region, the depolarization temperature (T d) increased below 1,160 °C then decreased at higher sintering temperature. The resistivity (ρ) of the Ce-BNT6BT ceramics increased linearly as the sintering temperature increased below 1,180 °C, but reduced as the sintering temperature increased further. A maximum value of the ρ was 3.125?×?1010 ohm m for the Ce-BNT6BT ceramics sintered at 1,180 °C at room temperature.  相似文献   

4.
0.55Pb(Ni1/3Nb2/3)O3-0.135PbZrO3-0.315PbTiO3 (PNN-PZ-PT) ternary piezoelectric ceramics with excess 1.0 wt.% PbO were synthesized by the conventional solid-state reaction method at 1175–1300 °C for 2 h, respectively. The influence of sintering temperature (T s) on microstructure, piezoelectric, dielectric, and ferroelectric properties were systematically investigated. The results of XRD and Raman scattering spectra demonstrated that a typical perovskite structure with mainly rhombohedral symmetry near the MPB region were obtained for all the samples. The tetragonal phase content was increased slightly with the increase of sintering temperature. In addition, with increasing T s the average grain size increases while the density decreases were also found. The results of electrical measurements confirmed that piezoelectric constant, dielectric constant, remnant polarization were firstly increased and then decreased with the increase of sintering temperature. The optimum and remarkable enhanced electrical properties of d 33?=?1070 pC/N, k p?=?0.69, ε r?=?8710, tanδ?=?0.026, P r?=?24.08 μC/cm2, and E c?=?3.2 kV/cm were obtained for the sample sintered at 1250 °C for 2 h. Meanwhile, the sample exhibits a typical relaxor ferroelectric behavior with the maximum dielectric constant ε m =24541 at Curie temperature T c?=?113.3 °C at 1 kHz.  相似文献   

5.
Lead-free piezoelectric ceramics are strongly needed to replace the lead-based piezoelectric ceramics with increasing environmental concerns. Barium titanate (BaTiO3) systems are one of the most promising candidates due to excellent electrical properties. However, the sintering temperature for traditionally sintered BaTiO3 ceramics are about 1300°C, which restricts the applications of BaTiO3 ceramics. It is necessary to develop high piezoelectric properties of BaTiO3 based ceramics which are able to sinter at low temperature. The (Ba0.94Cax)Ti0.94Oδ-0.04LiF (x?=?0.00?~?0.05 mol) ceramics were synthesized by a conventional sintering method at 1050°C. All the samples show high relative densities over 90%. X-Ray Diffraction pattern indicated that the crystallographic structure of the samples (x?=?0.00 and 0.01 mol) are orthorhombic phase and changes to pseudocubic one with increasing Ca content to x?=?0.03 mol. Two-phases with orthorhombic and pseudocubic symmetries coexisted at x?=?0.02 mol, which contributes the excellent properties, in which the piezoelectric constant d 33?=?361 pC/N, the planar electromechanical coupling coefficient kp?=?41.2%, the Curie temperature Tc?=?70°C, the temperature of phase transition T O-PC?=?34°C near the room temperature, the relative permittivity ε r?=?4028 and the remanent polarization P r?=?9.39 μC/cm2.  相似文献   

6.
Pb(Mn1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3–Pb(Zr0.48Ti0.52)O3 (abbreviated as PMN–PZN–PZT) ceramics containing Li2CO3, Bi2O3 and CuO as sintering aids were fabricated using two-stage calcinations method in order to develop low temperature sintering ceramics for multilayer piezoelectric actuators. Their dielectric and piezoelectric properties were investigated according to the variation of sintering time. All the specimens sintered at 930°C for 60~150 min showed tetragonal phases without secondary phases. Electromechanical coupling factor (kp), dielectric constant (ε r) and piezoelectric constant (d 33) increased with the increase of the sintering time. The mechanical quality factor (Qm) exhibited maximum of 1,815 with the increase of sintering time for 120 min and then slightly decreased. At the sintering temperature of 930°C and the sintering time of 120 min, the optimal values such as the density of 7.69 g/cm3, kp of 0.516, ε r of 1158, Qm of 1815, and d 33 of 287 pC/N were found for multilayer piezoelectric actuators.  相似文献   

7.
High performance lead-free (K0.49Na0.51)0.98Li0.02(Nb0.77Ta0.18Sb0.05)O3?+?0.5 mol%BaZrO3 piezoelectric ceramic was selected as base material, while BaO-CuO-B2O3-MnO2 frit was used as sintering aid to lower the sintering temperature. The effect of BaO-CuO-B2O3-MnO2 frit doping amount on the sintering behavior, structure and electrical properties of the ceramics was investigated. The optimal sintering temperature of the ceramics decreased with the increase of frit doping amount. The ceramic with frit doping amount of 1.0 wt.%, sintered at a reduced temperature of 1100°C, exhibited optimal electrical properties as follows: piezoelectric constant d 33?=?345 pC/N, planar electromechanical coupling coefficient k p?=?44.5 %, mechanical quality factor Q m?=?135, dielectric constant ε 33 T ?=?1210, and dielectric loss tanδ?=?0.018. Together with its relatively high T c?=?195°C, this ceramic was an excellent candidate for replacing the lead-based piezoceramics in practical applications.  相似文献   

8.
A novel microwave dielectric ceramics with composition of Ca2Zn4Ti15O36 (CZT) have been synthesized at different sintering temperatures, using citrate sol-gel derived powder. The sintering behavior and the phase identification of the powders were evaluated using differential thermal analysis-thermo gravimetric analysis and X-ray powder diffraction analysis techniques. The phase of CZT can be observed in the powder calcined at 900 °C. The single-phase of CZT, however, can only be obtained at sintering temperature of 1,000 °C or above. The single-phase CZT ceramics can be sintered into dense at 1,100 °C, exhibiting excellent microwave dielectric properties of ? r?=?48.1, Q?×?f?=?27,000 GHz, and τ f?=?+53.5 ppm/°C. The effects of sintering temperature on the density, microstructure, and dielectric properties of the sintered ceramics were investigated. The mechanism responsible for the change of dielectric properties with sintering temperature was also discussed.  相似文献   

9.
The objective of this work is to lower the sintering temperature of Ba0.91Ca0.09Ti0.916Sn0.084O3 (BCTS) ceramics without sacrificing the piezoelectric performance. The low-temperature sintering technique has been conducted to prepare the BCTS ceramics by adding two additives of ZnO and MnO2. The ceramics endure a phase transition from a ferroelectric tetragonal phase to a pseudo-cubic relaxor ferroelectric with increasing MnO2 content. The addition of ZnO and MnO2 decreases the sintering temperature greatly, positively affecting their dielectric and piezoelectric properties. An enhanced electrical behavior of d 33?~?495 pC/N, k p?~?43.0 %, ε r?~?5429, and tan δ?~?1.54 % has been observed in the ceramic with x?=?0.1 wt% when sintered at ~1315 °C. As a result, the method to dope two additives of ZnO and MnO2 can effectively improve the piezoelectric properties of BaTiO3-based ceramics sintered at a low temperature.  相似文献   

10.
A 0.655Pb(Mg1/3Nb2/3)O3-0.345PbTiO3 (PMN-0.345PT) functionally graded (FG) piezoelectric actuator was fabricated by tape-casting. The effects of sintering temperature on the physical and electrical properties of the PMN-PT ceramics were initially investigated. High dielectric and piezoelectric properties of d 33?=?700pC/N, k p?=?0.61, ??r?=?4.77?×?103, tan???=?0.014, P r?=?30.68 ??C/cm2 were obtained for the specimens sintered at 1200°C. Compared with the traditional solid-state reaction, the properties of the ceramics were significantly enhanced by tape-casting. The new FG piezoelectric actuator consisted of four layers, and the variation of changes in their d 33 and ?? r were graded opposite the thickness direction. The relationship between displacement and voltage for the actuator was also determined, with the results showing that it was linear. The driving displacement of the free end of the actuator reached 430.668 ??m.  相似文献   

11.
The addition of powdered 0.5 Li2O–0.5K2O–2B2O3 (LKBO) glass (0.5 to 2 wt%) to potassium sodium niobate, K0.5Na0.5NbO3 (KNN) powder facilitated higher densification which resulted in improved physical properties that include dielectric, piezoelectric and ferroelectric. The required polycrystalline powders of KNN were synthesized through solid-state reaction route, while LKBO glass was obtained via the conventional melt-quenching technique. Pulverized glass was added to KNN powders in different wt% and compacted at room temperature and these were sintered around 1100°C. Indeed the addition of optimum amount (1 wt %) of LKBO glass to KNN ceramics facilitated lowering of sintering temperature accompanied by larger grains (8 µm) with improved density. The dielectric constant (?r) measured at room temperature was 475 (at 10 kHz), whereas it was only 199 for the LKBO glass free KNN. The piezoelectric coefficient (d33) was found to be 130 pC/N for 1 wt% LKBO added glass, which was much higher than that of pure KNN ceramics (85 pC/N). Indeed, the LKBO glass added samples did exhibit well saturated P versus E hysteresis loops at room temperature. Though there was no particular trend observed in the variation of Pr with the increase in glass content, the Pr values were higher than that obtained for KNN ceramics. The improved physical properties of KNN ceramics encountered in these studies were primarily attributed to enhancement in density and grain size.  相似文献   

12.
A (100-x)Pb(Yb1/2Nb1/2)O3-xPbTiO3 [PYN-PTx] solid solution system with 49.0????×????51.0 was prepared using a conventional ceramics process and sintered at low temperature. When excess PbO was added into the PYN-PTx system, all samples were sintered at temperatures as low as 800°C with good dielectric and piezoelectric properties. It is suggested that a liquid phase with excess PbO was formed during the sintering and improved the densification of PYN-PTx ceramics at low temperatures. For the PYN-PTx binary system, it was found that the temperature dependence of the relative permittivity follows a Curie?CWeiss Law above the deviation temperature (TD) at high temperatures. Good piezoelectric properties of d 33 ?=?510 pC/N, ?? r ?=?2800 at RT, k p?=?0.57, and k t?=?0.42 with Tc?=?373°C were obtained for PYN-PT49.5 ceramics sintered at 800°C for 8 h.  相似文献   

13.
Perovskite-type Pb1.04(Mn1/3Sb2/3)0.05Zr0.47Ti0.48O3 + 0.15 wt.%SrCO3 + 0.15 wt.% MnO2 sintered at 1180 °C for 2 h exhibited high piezoelectric and dielectric properties of ε33 T0?=?1518, tanδ?=?0.32 %, d33?=?320PC/N, kp?=?0.58 respectively. The sintering temperature of the above-mentioned matrix was decreased from 1180 °C to 925 °C with the addition of a small amount of CuO without reducing properties. The SrCO3 and CuO could react with PbO and formed a liquid phase during the sintering, which assisted densification of the specimens. The piezoelectric and dielectric properties were changed with the containing of CuO for 0.05 wt.%–1.5 wt.%. The result showed that the specimen sintered at 925 °C had the good piezoelectric properties of ρ?=?7.9 g/cm3, tanδ?=?0.0041, d33?=?289pC/N, Tc?=?260 °C, Kp?=?0.56, ε33 T0?=?1621. Specimens owned these piezoelectric properties could be good candidate for multilayer piezoelectric transformers.  相似文献   

14.
(1-x) (Na0.5Bi0.5TiO3)-xK0.5Na0.5NbO3/NBT-xKNN [x?=?0.07, 0.06, 0.05] ferroelectric ceramics were prepared by solid state synthesis route (SSSR). The effects of KNN contents on the microstructure, dielectric, piezoelectric and ferroelectric properties of the NBT-xKNN system were investigated in detail. For single perovskite phase formation, the calcination temperature was optimized at 800 °C for 6 h. From the XRD study, the morphotropic phase boundary (MPB) was confirmed for x?=?0.07 composition. For better densification, the sintering temperature was optimized for 1150 °C for 4 h. SEM micrographs illustrate the closely packed and non-uniform distribution of grains. Diffusive type of behaviour was observed in all the ceramics. Polarization (P) vs. electric field (E) study confirmed the ferroelectric nature of the NBT-xKNN ceramics. The bipolar field-induced strain measurement for all the ceramic samples showed butterfly-shaped loops indicating their piezoelectric nature. Among all the different compositions in MPB region, high dielectric constant (εr) of?~?3011, high remnant polarization (P r ) of 17.88μC/cm2 and high strain % of 0.41, were obtained in NBT-xKNN system with x?=?0.07 confirming the existence of MPB at this composition.  相似文献   

15.
The piezoelectric properties of (1?x)(Bi0.5Na0.5)TiO3-xBaTiO3 ceramics were reported and their piezoelectric properties reach extreme values near the MPB (about x?=?0.06). The X-ray analysis of (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics for all compositions exhibited a pure perovskite structure without any secondary phase. Within a certain ratio of contents, the co-doped ceramics enhanced piezoelectric coefficient (d 33 ), lowered the dielectric loss, and increased the sintered density. The temperature dependence of relative dielectric permittivity (K 33 T ) reveals that the solid solutions experience two phase transitions, ferroelectric to anti-ferroelectric and anti-ferroelectric to relaxor ferroelectric, which can be proven by P-E hysteresis loops at different temperatures. In addition, the specimen containing 0.04/0.01 wt.% CaO/MnO showed that the coercive field E c was a minimum value of 26.7 kV/cm, while the remnant polarization P r was a maximum value of 38.7 μC/cm2, corresponding to the enhancement of piezoelectric constant d33 of 179 pC/N, electromechanical coupling factor k p of 37.3%, and relative dielectric permittivity K 33 T of 1137. (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics co-doped with CaO/MnO were considered to be a new and promising candidate for lead-free piezoelectric ceramics owing to their excellent piezoelectric/dielectric properties, which are superior to an un-doped BNBT system.  相似文献   

16.
Abstract

BaTi0.91Sn0.09O3 (BTS) ceramics were synthesized by the solid state combustion method with glycine as the reducting agent and metal nitrates as the oxidants. The calcination and sintering temperatures were in the range of 1200?°C–1300?°C and 1300?°C–1450?°C, respectively, for 2?h. Pure perovskite powders were obtained from the samples calcined at ≥1275?°C for 2?h. The crystal size calculated by Scherrer equation was in the range of 22–30?nm. XRD results of the sintered ceramics showed the coexistence of the tetragonal (T) and orthorhombic (O) phases in all samples, and were confirmed by Rietveld refinement. The grain sizes increased from 9.04 to 29.83 µm when the sintering temperatures increased from 1300?°C–1450?°C for 2?h. The highest density (5.95?g?cm?3), large piezoelectric strain (d33* = 830?pm/V) and best dielectric constant (εr = 14841) were obtained from the sample sintered at 1350?°C for 2?h. This study clearly demonstrates the potential of the solid state combustion method for producing high density and good dielectric properties in BTS ceramics.  相似文献   

17.
High dielectric Na0.5Bi0.5Cu3Ti4O12 (NBCTO) ceramics were firstly prepared by co-precipitation method at low temperature. X-ray diffraction results revealed that pure phase of NBCTO was achieved by calcination at 950 °C for 2 h. Thermo-gravimetric analysis on a dried NBCTO precursor was carried out to study the thermal decomposition process. The microstructure and dielectric properties of NBCTO ceramics sintered at different temperatures were investigated. The results indicate that the sintering temperature has a sensitive influence on the microstructure and dielectric properties. Higher sintering temperature gave rise to increased dielectric constant and dielectric loss of NBCTO samples, and the sample sintered at 975 °C for 8 h exhibits high dielectric constant of 8.3?×?103 and low dielectric loss of 0.069 at 10 kHz. The dielectric properties were further discussed by the impedance spectroscopy.  相似文献   

18.
ABSTRACT

Lead-free piezoelectric ceramics (K0.5Na0.5)(Nb1-xSbx)O3+0.5 mol.%MnO2, where x = 0 ÷ 0.10, with single phase structure and rhombohedral symmetry at room temperature were prepared by conventional ceramic technology. The optimal sintering temperatures of compositions were within 1100°–1140°C. MnO2 functions as a sintering aid and effectively improves the densification. The samples reached density from 4.26 g/cm3 for undoped (K0.5Na0.5)NbO3 to 4.40 g/cm3 for Mn/Sb5+ co-doped ceramics. The co-effects of MnO2 doping and Sb5+ substitution lead to significant improvement in dielectric and piezoelectric properties: ε at the Tc increased from 6000 (KNN) to 12400 (x = 0.04), d33 = 92 ÷ 192 pC/N, kp = 0.32 ÷ 0.46, kt = 0.34 ÷ 0.48.  相似文献   

19.
[Bi1-z(Na1-x-y-zKxLiy)]0.5BazTiO3 lead-free piezoelectric ceramics were fabricated by ordinary ceramic technique and the piezoelectric and ferroelectric properties of the ceramics were studied. The ceramics can be well sintered at 1,100–1,150 °C for 2 h. X-ray diffraction (XRD) analysis shows that K+, Li+ and Ba2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a solid solution with a single-phase perovskite structure. The introduction of K+, Li+ and Ba2+ into Bi0.5Na0.5TiO3 significantly decreases the coercive field E c but maintains the large remanent polarization P r of the materials. The ceramics provide piezoelectric constant d 33 of 205 pC/N, electromechanical coupling factor k p of 0.346, remanent polarization P r of 31.7–38.5 μC/cm2, and coercive field E c of 3.18–5.16 kV/mm.  相似文献   

20.
In this study, in order to develop the composition ceramics for low loss and low temperature sintering multilayer piezoelectric actuator, Pb(Mn1/3Nb2/3)O3–Pb(Ni1/3Nb2/3)O3–Pb(Zr0.50Ti0.50)O3 (abbreviated as PMN-PNN-PZT) ceramics were fabricated using Li2CO3 and Na2CO3 as sintering aids, and their piezoelectric and dielectric characteristics were investigated according to the amount of MnO2 addition. At the 0.2 wt% MnO2 doped specimen sintered at 900 °C, density and mechanical quality factor (Q m) showed the maximum values of 7.81[g/cm3]and 1186, respectively. And also, at 0.1 wt% MnO2 doped specimen, electromechanical coupling factor (k p), piezoelectric constant (d 33) of specimen showed the maximum values of 0.608 and 377[pC/N], respectively. Dielectric constant (? r) slightly decreased with increasing MnO2. Taking into consideration the density of 7.81[g/cm3], electromechanical coupling factor (k p)of 0.597 the mechanical quality factor (Q m) of 1,186, and piezoelectric constant (d 33) of 356[pC/N], it could be concluded that 0.2 wt% MnO2 doped composition ceramics sintered at 900 °C was best for low loss and low temperature sintering multilayer piezoelectric actuator application.  相似文献   

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