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1.
The effects of NaF on the microstructure and electrical properties of K0.5Na0.5Nb0.95Ta0.05 lead-free ceramics prepared by conventional sintering method were investigated in this study. The dopant NaF effectively lowers the sintering temperature and promotes the grain growth. Samples with a high relative density up to 96.3 % are achieved by adding 0.6 wt% NaF to improve the sinterability. The electric properties are also enhanced, and the optimum properties are achieved at the doping content of 1.0 wt% (d 33 = 153 pC/N, k P = 32.2 %, Q m = 80.5, E c = 0.89 kV/mm, and P r = 16.5 μC/cm2). The improvement of ferroelectric and piezoelectric properties is suggested to be largely contributed to the compensation of sodium element from dopant NaF for the volatilization of A-site alkali elements. 相似文献
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Sitalo EI Raevski IP Lutokhin AG Blazhevich AV Kubrin SP Raevskaya SI Zakharov YN Malitskaya MA Titov VV Zakharchenko IN 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(9):1914-1919
Dielectric, X-ray, and piezoelectric studies of highly-resistive Li-doped (1-x)PbFe(1/2)Nb(1/2)O(3)-(x)PbTiO(3) (PFN-xPT) ceramics from the 0 ≤ x ≤ 0.2 range fabricated by solid-state synthesis and usual sintering have been carried out. Distinct anomalies of dielectric and piezoelectric parameters, corresponding to the transition between rhombohedral (monoclinic) and tetragonal ferroelectric phases, have been observed in pure PFN and PFN-xPT compositions with PbTiO(3) content up to 8 mol.%. The x,T-phase diagram of the PFN-xPT solid solution system has been constructed using these data. 相似文献
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40CaO–20B2O3–40SiO2 (abbreviate as CBS) glass-doped Sr0.5Ba0.5Nb2O6 (SBN50) ceramics were fabricated by solid-state ceramic route. The effects of CBS glass addition on the firing, the phase
formation, the microstructure and dielectric characterization of SBN50 ceramics were investigated. Results show that the density
of the samples firstly increase and then slightly decrease with increasing CBS glass content and the highest density achieved
has been 97% of the theoretical density for the sample with 2% (mass fraction) CBS glass. The sintering temperature was significantly
reduced from 1,350 to 1,100 °C. X-ray diffraction analysis shows the single phase tungsten bronze type structure is preserved
up to 2% CBS glass. However, the samples with more than 5% CBS glass are found to have a secondary phase CaNbO3. The diffuse character and the dielectric constant at room temperature increase as CBS glass content increases. The dielectric
constant of the samples at the Curie temperature (T
c) firstly increases and then decreases with increasing the content of CSB glass. Interestingly, the grain sizes of SBN phase
are found to obviously increase with increase in CBS glass doping level. 相似文献
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Xinyou Huang Wenbo Zhao Chunhua Gao Zhigang Chen 《Journal of Materials Science: Materials in Electronics》2014,25(1):505-509
Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZ) lead-free piezoelectric ceramics doped with Nb2O5 (0.1, 0.3, 0.5, 0.7, 0.9 wt%) and Li2CO3 (0.6 wt%) were prepared by conventional solid-state reaction method. Influence of Nb2O5 doping amount on the piezoelectric property, dielectric property, phase composition and microstructure of prepared BCTZ lead-free piezoelectric ceramics doped with Li2CO3 were investigated by X-ray diffraction and scanning electron microscopy and other analytical methods. The results showed that the sintered temperature decreased greatly when the BCTZ lead-free piezoelectric ceramics were co-doped with Nb2O5 and Li2CO3; a pure perovskite structure of BCTZ lead-free piezoelectric ceramics co-doped with Nb2O5 and Li2CO3 sintered at 1,020 °C could be also obtained. The grain size decreased when Nb2O5 doping amount increased. The piezoelectric constant (d33), the planar electromechanical coupling factor (kp), the relative dielectric constant (εr) of BCTZ ceramics doped with Li2CO3 increased firstly and then decreased, the dielectric loss (tanδ) decreased firstly and then increased when Nb2O5 doping amount increased, indicating that Nb2O5 was “soft” additive. When Nb2O5 doping amount (z) was 0.7 wt% and Li2CO3 doping amount was 0.6 wt%, the BCTZ ceramics sintered at 1,020 °C possessed the best piezoelectric property and dielectric property, which d33 was 238 pC/N, kp was 29.33 %, εr was 4,691, tanδ was 2.07 %. 相似文献
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《Materials Research Bulletin》2006,41(7):1385-1391
CaTi1−x(Fe0.5Nb0.5)xO3 (0 ≤ x ≤ 1) dielectrics were synthesized via the solid state reaction route and structure analysis was performed together with the dielectric characterization. The substitution of Ti4+ by Fe3+/Nb5+ and developed phase were studied by X-ray diffraction. The dielectric constant and temperature coefficient of resonant frequency decrease rapidly with an increase of x. The influence of 1–5 wt.% B2O3 as a sintering additive investigated at CaTi0.5(Fe0.5Nb0.5)0.5O3 solid solutions. The dielectric properties were found to strongly depend on the sintering conditions and contents of B2O3 additions. ɛr = 52.3, Q × fo = 2930 GHz and Tf = 13 ppm/°C were obtained for CaTi0.5(Fe0.5Nb0.5)0.5O3 specimen 3 wt.% B2O3 sintered at 900 °C for 2 h. 相似文献
9.
Roopam Gaur K. Chandramani Singh Radhapiyari Laishram 《Journal of Materials Science》2013,48(16):5607-5613
Ferroelectric (K0.455Li0.045Na0.5)(Nb0.9Ta0.1)O3 + x mol% BaCO3 ceramic compositions with Ba2+ as an A-site dopant in the range of x = 0–1.2 mol% were synthesized by conventional ceramic processing route. Effect of Ba2+ content on the microstructure, ferroelectric, dielectric, and piezoelectric properties of the ceramics was investigated. The results of X-ray diffraction reveal that Ba2+ diffuse into the (K0.455Li0.045Na0.5)(Nb0.9Ta0.1)O3 lattices to form a solid solution with a perovskite structure having typical orthorhombic symmetry. As Ba2+ content increases, cell volume and tetragonality increase in the crystal structure of the ceramics. Increasing doping level of Ba2+ inhibits grain growth in the ceramics and reduces both the Curie temperature (T c) and tetragonal–orthorhombic phase transition temperature (T o-t). The bulk density, remnant polarization P r, room-temperature dielectric constant (ε′RT), planar electromechanical coupling factor k p , and piezoelectric charge coefficient d 33 are found to increase as Ba2+ concentration increases from 0 to 0.8 mol% and then decrease as Ba2+ content increases further from 0.8 to 1.2 mol%. High piezoelectric properties of d 33 = 187 pC/N and k p = 48 % are found in 0.8 mol% Ba2+ composition. Optimum amount of Ba2+ dopant takes the polymorphic phase boundary region consisting of orthorhombic and tetragonal crystal structures of the ceramic system near the room temperature and enhances its piezoelectric properties. 相似文献
10.
Qiaoji Zheng Jian Ma Dunmin Lin 《Journal of Materials Science: Materials in Electronics》2013,24(10):3836-3843
Lead-free ceramics (Bi1?xLax)0.5(Na0.84K0.16)0.5TiO3 were prepared by a conventional ceramic technique and the effects of La doping and sintering temperature on the microstructure, ferroelectric and piezoelectric properties of the ceramics were studied. All the ceramics possess a pure perovskite structure and La3+ diffuses into the Bi0.5(Na0.84K0.16)0.5TiO3 lattices to form a solid solution with a rhombohedral symmetry. The addition of La leads to the significant change in the grain morphology and size for the (Bi1?xLax)0.5(Na0.84K0.16)0.5TiO3 and a number of rod grains with the length of 10–50 μm and the diameter of 1–2 μm are observed in the ceramic with x = 0.04 sintered at 1,140 °C for 2 h. However, as sintering temperature increases to 1,160 °C, the rod grains disappears and the uniform and rectangular grains are observed in the ceramics with x = 0.04. As x increases from 0 to 0.06, the coercive field E c of the ceramics decreases from 4.33 to 2.81 kV/mm and the remanent polarization P r of the ceramics retains the high values of 25.9–27.7 μm/cm2. The depolarization temperature T d decreases from 154 to 50 °C with x increasing from 0 to 0.10. All the ceramics exhibit the diffusive phase transition at high temperature (280–320 °C). The ceramic with x = 0.04 sintered at 1,150 °C for 2 h exhibit the optimum piezoelectric properties, giving d 33 = 165 pC/N and k p = 32.9 %. The optimum sintering temperature is 1,150 °C at which the improved piezoelectric properties (d 33 = 165 pC/N and k p = 32.9 %) are obtained. At the high La3+ level (x = 0.10 and 0.12), the ceramics exhibit weak ferroelectricity (P r = 13.0–21.2 μm/cm2) and thus possess poor piezoelectricity (d 33 = 17–27 pC/N). 相似文献
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Ping Zhang Lingxia Li Guochao Li Wei Zhang 《Journal of Materials Science: Materials in Electronics》2010,21(3):213-217
Ceramics of Li1.1Nb0.58Ti0.5O3-xBi2O3 with low sintering temperature have been prepared by the solid-solution reaction method using B2O3 (2 wt% added) as sintering aid. For all compounds, the sintering temperature achieves 900 °C. Microstructure and dielectric properties of Li1.1Nb0.58Ti0.5O3-2 wt% B2O3-xBi2O3 (LNT-B-xBi) ceramics have been investigated. The X-ray diffraction patterns indicate for higher Bi2O3 content (x = 0.1 mol%) that the material is composed by two phases identified as M-phase and Bi4Ti3O12. The Li1.1Nb0.58Ti0.5O3 + 0.15 mol% Bi2O3 composition sintered at 900 °C with B2O3 addition exhibits attractive dielectric properties (ε r = 59.68, tan δ = 1.2×10?4 and a temperature coefficient of the relative permittivity near zero) at 1 MHz. It is also shown that the introduction of Bi2O3 can tune the temperature coefficient of the relative permittivity. All dielectric properties lead this system compatible to manufacture sliver based electrodes multilayer dielectric devices. 相似文献
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Qiang Li Hairong Wang Huiqing Fan Changbai Long Xiao Liu 《Journal of Materials Science》2014,49(1):211-217
The modified (Na0.5Bi0.5)0.94Ba0.03La0.02Ti0.995Mn0.005O3 lead-free ceramics were prepared using a traditional solid-state reaction process, and their structures were characterized by X-ray diffraction, scanning electron microscope, and Raman spectroscopy, respectively. A double-like P–E loop was discussed at the room temperature for the co-doped ceramics by reason of the appearance of the anti-ferroelectric. The ferroelectric hysteresis loop and field-induced strain were studied at different temperatures. A large strain (S 33 = 0.33 %, E = 50 kV/cm at 120 °C) was observed due to the transformation between ferroelectric and anti-ferroelectric phase at the phase transition temperature. Also, the depolarization temperature (T d) of the co-doped ceramics was determined from the pyroelectric current density versus temperature plots, which was consistent with the result from the position of dielectric loss’s peak as a function of temperature. 相似文献
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《Materials Research Bulletin》2013,48(11):4907-4910
Aurivillius-type ceramic, Sr0.6(BiNa)0.2Bi2Nb2O9 (SBNBN), was synthesized by using conventional solid-state processing. Phase structure and microstructural morphology were confirmed by X-ray diffraction analyses (XRD) and the scanning electron microscopy (SEM). Dielectric, piezoelectric and electromechanical properties of the SBNBN ceramic were investigated in detail. Curie temperature (Tc), piezoelectric coefficient (d33), electromechanical coupling coefficient kp, kt and quality factor Qm of the SBNBN ceramic were found to be 586.5 °C, 22 pC/N, 5.0%, 8.7% and 651, respectively. In addition, the reasons for varieties of the resistivity and dielectric properties at high temperature were also discussed. 相似文献
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Huanfu Zhou Hong Wang Kecheng Li Xi Yao 《Journal of Materials Science: Materials in Electronics》2009,20(3):283-288
The effects of B2O3–CuO (BCu, the weight ratio of B2O3 to CuO is 1:1) addition on the sintering behavior, microstructure, and the microwave dielectric properties of 3Li2O–Nb2O5–3TiO2 (LNT) ceramics have been investigated. The low-amount addition of BCu can effectively lower the sintering temperature of
LNT ceramics from 1125 to 900 °C and induce no obvious degradation of the microwave dielectric properties. Typically, the
2 wt% BCu-added ceramic sintered at 900 °C has better microwave dielectric properties of ε
r
= 50.1, Q × f = 8300 GHz, τ
f
= 35 ppm/°C. Silver powders were cofired with the dielectric under air atmosphere at 900 °C. The SEM and EDS analysis showed
no reaction between the dielectric ceramic and silver powders. This result shows that the LNT dielectric materials are good
candidates for LTCC applications with silver electrode. 相似文献
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Yih-Chien Chen Yung-Yu Chen Shi-Li Yao 《Journal of Materials Science: Materials in Electronics》2013,24(4):1150-1157
This study elucidates the microwave dielectric properties and microstructures of Nd(Mg0.5?xNixSn0.5)O3 ceramics with a view to their potential for microwave devices. The Nd(Mg0.5?xNixSn0.5)O3 ceramics were prepared by the conventional solid-state method with various sintering temperatures. The X-ray diffraction patterns of the Nd(Mg0.43Ni0.07Sn0.5)O3 ceramics revealed no significant variation of phase with sintering temperatures. A dielectric constant ( $ \varepsilon_{r} $ ) of 19.3 and a quality factor (Q × f) of 93,400 GHz and a temperature coefficient of resonant frequency ( $ \tau_{f} $ ) of ?66 ppm/ °C were obtained for Nd(Mg0.43Ni0.07Sn0.5)O3 ceramics that were sintered at 1,550 °C for 4 h. 相似文献
18.
Shaochun Li Qilong Zhang Tiejun Zhao Zuquan Jin Yongjuan Geng 《Journal of Materials Science: Materials in Electronics》2013,24(4):1081-1085
Multilayer Li1.075Nb0.625Ti0.45O3 (LNT) ceramics for low temperature co-fired ceramic (LTCC) application were prepared by aqueous tape casting. The rheological test indicated that the aqueous slurries exhibited a typical shear-thinning behavior without thixotropy suitable for tape casting process. The green tapes with 2 wt% V2O5 addition have satisfactory mechanical properties. Scanning electron microscopy studies revealed that the green tapes have a smooth defect-free surface and that the sintered LNT ceramics have a fine grain microstructure with a uniform grain size. Therefore, aqueous tape casting is suitable for the manufacture of high performance multilayer LNT ceramics. Silver inner-electrode was sintered with LNT tapes at 900 °C, and no reaction been observed between LNT ceramic and sliver layers. The addition of V2O5 does not induce much degradation on the microwave dielectric properties. In the case of 2 wt% V2O5 addition, the ceramics show good microwave dielectric properties of ε r = 65, Q × f = 6,350 GHz. It represents that LNT ceramics could be promising for multilayer LTCC application. 相似文献
19.
Low-temperature firing and microwave properties of TiO2 modified Li2ZnTi3O8 ceramics doped with B2O3
The low-temperature firing and microwave properties TiO2 modified Li2ZnTi3O8 ceramics with B2O3 addition have been developed. B2O3 addition could reduce the sintering temperature of Li2ZnTi3O8 ceramics from 1,150 to 900 °C, which is attributed to the formation of liquid phases during the sintering process observed by SEM. The 1.5 wt% B2O3 doped Li2ZnTi3O8 ceramics sintered at 900 °C have ε r = 23.3, Q × f = 48,817 GHz, and resonant frequency τ f = ?15.35 × 10?6/°C. Further, due to the compensating effect of rutile TiO2 (τf = 450 ppm/°C), the temperature coefficient of τf for with TiO2 was adjusted to near zero value. The 1.5 wt% B2O3 doped Li2ZnTi3O8 ceramics with 3 wt% TiO2 dielectrics sintered at 900 °C exhibited the optimal microwave properties: εr = 25.9, Q × f = 46,487 GHz, and τf = ?0.35 ppm/°C. 相似文献
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J. Su J. T. Zhang X. M. Lu C. J. Lu J. He Q. C. Li J. Zhou J. S. Zhu 《Journal of Materials Science》2014,49(10):3681-3686
The ceramic TbCo0.5Mn0.5O3.07 of double-perovskite structure was prepared by solid-state reaction. Its crystal structure and magnetic and dielectric properties were investigated by first-principles calculations and experimental observations. TbCo0.5Mn0.5O3.07 possesses a monoclinic structure with P21/n space group. The c axis is the easy-magnetization axis, and it is largely caused by Co2+ anisotropy. The predominant valence states are Mn4+ and Co2+, with a small amount of Co3+ coexisting with Co2+. The ordering of Mn4+ and Co2+ results in ferromagnetic Mn4+–Co2+ interactions. Partial disorder of the B-site creates antiferromagnetic Co2+–O–Co2+ or Mn4+–O–Mn4+ interactions. The origin of metamagnetism is associated with the coexistence of antiferromagnetic and ferromagnetic phases. The magnetic exchange bias is strongly dependent on magnetic field, which is considered to be related to the metamagnetic behavior. The possibility of spin glass behavior is excluded by AC susceptibility measurements. The two observed dielectric relaxations are caused by electrons hopping between Co2+ and Mn4+ and between Co3+ and Mn4+. 相似文献