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1.
Ga2O3 was doped into 0.95(K0.48Na0.52)NbO3—0.05LiTaO3 (KNN—LT) ceramics and its influences on the sintering behavior, phase structure and electrical properties of ceramics were studied. Firstly, SEM observation exhibits that more and more glass phase appears in ceramics with the gradual addition of Ga2O3, which determines the continuous decrease in sintering temperatures. And the addition of Ga2O3 is also found to increase the orthorhombic—tetragonal transition temperature (TO—T) of system to a higher level. Secondly, both the density and the coercive field (EC) of ceramics increase firstly and then decrease with increasing the Ga2O3 content, and the KNN—LT—xGa sample at x = 0.004 shows a pinched P—E hysteresis loop. Finally, the impedance characteristics of KNN—LT—xGa ceramics were investigated at different temperatures, revealing a typical vacancy related conduction mechanism. This work demonstrates that Ga2O3 is a good sintering aid for KNN-based ceramics, and the vacancy plays an important role in the sintering and electrical behaviors of ceramics. 相似文献
2.
Lead-free (K0.5Na0.5)(Nb1-xGe x )O3 (KNN-xGe, where x = 0-0.01) piezoelectric ceramics were prepared by conventional ceramic processing. The effects of Ge4+ cation doping on the phase compositions, microstructure and electrical properties of KNN ceramics were studied. SEM images show that Ge4+ cation doping improved the sintering and promoted the grain growth of the KNN ceramics. Dielectric and ferroelectric measurements proved that Ge4+ cations substituted Nb5+ ions as acceptors, and the Curie temperature (TC) shows an almost linear decrease with increasing the Ge4+ content. Combining this result with microstructure observations and electrical measurements, it is concluded that the optimal sintering temperature for KNN-xGe ceramics was 1020°C. Ge4+ doping less than 0.4 mol.%can improve the compositional homogeneity and piezoelectric properties of KNN ceramics. The KNN-xGe ceramics with x = 0.2% exhibited the best piezoelectric properties: piezoelectric constant d33 = 120 pC/N, planar electromechanical coupling coefficient kp = 34.7%, mechanical quality factor Qm = 130, and tanδ = 3.6%. 相似文献
3.
Bo Wu Jian Ma Wenjuan Wu Min Chen 《Journal of Materials Science: Materials in Electronics》2017,28(3):2358-2365
In this work, (Ba0.96Ca0.04)(Ti0.92Sn0.08)O3–xmol MnO (BCTS–xMn) lead-free piezoelectric ceramics were fabricated by the conventional solid-state technique. The composition dependence (0 ≤ x ≤ 3.0 %) of the microstructure, phase structure, and electrical properties was systematically investigated. An O–T phase structure was obtained in all ceramics, and the sintering behavior of the BCTS ceramics was gradually improved by doping MnO content. In addition, the relationship between poling temperature and piezoelectric activity was discussed. The ceramics with x = 1.5 % sintering at temperature of 1330 °C demonstrated an optimum electrical behavior: d 33 ~ 475 pC/N, k p ~ 50 %, ε r ~ 4060, tanδ ~ 0.4 %, P r ~ 10.3 μC/cm2, E c ~ 1.35 kV/mm, T C ~ 82 °C, strain ~0.114 % and \(d_{33}^{*}\) ~ 525 pm/V. As a result, we achieved a preferable electric performance in BaTiO3-based ceramics with lower sintering temperature, suggesting that the BCTS–xMn material system is a promising candidate for lead-free piezoelectric ceramics. 相似文献
4.
Xing-an Jiang Xiang-ping Jiang Chao Chen Na Tu Yun-jing Chen Ban-chao Zhang 《材料科学前沿(英文版)》2016,10(1):31-37
Na0.5Bi4.5?x Eu x Ti4O15 (NBT- x Eu3+) ceramics with x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 and 0.40 were prepared by conventional ceramics processing. NBT-0.25Eu3+ ceramics show the strongest red and orange emissions corresponding to the 5D0 → 7F2 (617 nm) and 5D0 → 7F1 (596 nm) transitions, respectively. The strongest excitation band around 465 nm matches well with the emission wavelength of commercial InGaN-based blue LED chip, indicating that Eu3+-doped NBT ceramics may be used as potential environmental friendly red-orange phosphor for W-LEDs application. As an inherent ferroelectric and piezoelectric material, the electrical properties of this potentially multifunctional electro-optical material have been also studied. The introduction of Eu3+ distinctly increased the Curie temperature (T C ) of NBT- x Eu3+ ceramics from 640°C to 711°C as x ranges from 0 to 0.40. For higher temperature applications, the electrical conductivity was also investigated. The conduction of charge carriers in high-temperature range originates from the conducting electrons from the ionization of oxygen vacancies. High T C and low tanδ makes Eu3+-doped NBTceramic also suitable for high temperature piezoelectric sensor applications and electro-optical integration. 相似文献
5.
M. N. Palatnikov N. V. Sidorov V. V. Efremov O. G. Gromov Yu. V. Radyush 《Inorganic Materials》2008,44(11):1240-1243
The dielectric permittivity of Li x Na1 ? x NbO3 ferroelectric solid solutions prepared at high pressures has been measured as a function of temperature and frequency, and their structural properties have been studied. The results demonstrate that ceramics samples of the Li x Na1 ? x NbO3 (x = 0.17, 0.25) ferroelectric perovskite solid solutions exhibit superionic conduction at relatively low temperatures (T ≥ 400 K). In the temperature range of superionic conduction, we observe significant dielectric dispersion and anomalies in permittivity, corresponding to structural transformations of the high-pressure solid solutions. 相似文献
6.
We have prepared magnetoelectric (ME) composite ceramics, free of foreign phases, in the lead zirconate titanate–cobalt nickel ferrite two-phase system: xPZT-36 + (100–x)Ni0.9Co0.1Fe2O4. The sol–gel derived ferrite powder used in our preparations seems to be doped with titanium cations from the PZT-36. The ceramics have a percolation threshold at x = 50–70 wt %, which is due to the increased electrical conductivity of Ni0.9Co0.1Fe2O4. As a consequence, the piezoelectric parameters of the ME ceramics drop sharply at x < 50–70 wt %: the piezoelectric moduli |dij| and piezoelectric voltage coefficients |gij| decrease by a factor of 3–5 in this composite range. The piezoelectric parameters |dij| and |gij| of the composites produced using the fine ferrite powder exceed those of the materials prepared using macrocrystalline Ni0.9Co0.1Fe2O4 powder by more than a factor of 2. The piezoelectric voltage coefficient g33 correlates with the ME coefficient ΔE/ΔH. The highest ME conversion efficiency (up to 45 mV/(cm Oe)) is offered by the 80 wt % PZT-36 + 20 wt % Ni0.9Co0.1Fe2O4 composites, whose composition lies in a subpercolation region. Even though the composites produced using the fine ferrite powder possess improved piezoelectric properties, they have smaller ΔE/ΔH coefficients (no greater than 25 mV/(cm Oe)), which can be tentatively attributed to the degradation of the properties of the ferrite as a consequence of doping with Ti4+ cations during the sintering of the composite ceramics. 相似文献
7.
Donor-doped lead-free Bi0.7Ba0.3(Fe0.7Ti0.3)1?x Nb0.66x O3 + 1 mol% MnO2 ceramics were prepared by a conventional oxide-mixed method and the effects of Nb-doping on microstructure, piezoelectric and ferroelectric properties of the ceramics were investigated. All the ceramics exhibit a pure perovskite structure with rhombohedral symmetry. The grain growth of the ceramics is inhibited after the addition of Nb doping. High electric insulation (R = 109–1010 Ω?cm) and the poor piezoelectric performance and weak ferroelectricity are observed after the addition of Nb2O5 in the ceramics. Different from the donor effect of Pb-based perovskite ceramics, the introduction of Nb into 0.7BiFeO3–0.3BaTiO3 degrades the piezoelectricity and ferroelectricity of the ceramics. The Bi0.7Ba0.3(Fe0.7Ti0.3)1?x Nb0.66x O3 + 1 mol% MnO2 ceramic with x = 0 exhibits the optimum piezoelectric properties with d 33 = 133 pN C?1 and k p = 0.29 and high Curie temperature (TC = 603°C). 相似文献
8.
Jun Wang Changrong Zhou Qingning Li Weidong Zeng Jiwen Xu Guohua Chen Changlai Yuan Guanghui Rao 《Journal of Materials Science》2018,53(12):8844-8854
Lead-free ceramics (1???x)Bi0.5Na0.5TiO3–xSr0.85Bi0.1TiO3 (BNT–xSBT, x?=?0.4, 0.5, 0.6 and 0.7) were prepared by a solid-state reaction process. Coexistence of ferroelectric relaxation at low temperature and Maxwell–Wagner dielectric relaxation at high temperature was revealed for the first time in this system. Meanwhile, hysteresis-free P–E loops combined with a very high piezoelectric strain coefficient (d33) of 1658 pC/N concurrently with large electrostrictive coefficient Q?=?0.287 m4C?2 were achieved. The ferroelectric relaxor behavior and large electrostrictive strain might be linked to easy reorientation and reversal of ergodic PNRs and the combined effect of Bi off-center position and lone pair electrons. 相似文献
9.
Lead-free ceramics (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3?x wt.%Cr2O3 (BCZT-xCr) were prepared via the conventional solid-state reaction method. The microstructure and electrical properties of BCZT-xCr samples were systematically studied. XRD and Raman results showed that all samples possessed a single phased perovskite structure and were close to the morphotropic phase boundary (MPB). With the increase of the Cr content, the rhombohedral-tetragonal phase transition temperature (T R-T) increases slightly, and the Curie temperature (T C) shifts towards the low temperature side. XPS analysis reveals that Cr3+ and Cr5 + ions co-existed in Cr-doped BCZT ceramics, indicating the different impact on the electrical properties from Cr ions as “acceptor” or “donor”. For the x = 0.1 sample, relative high piezoelectric constants d 33 (~316 pC/N) as well as high Q m (~554) and low tanδ (~0.8%) were obtained. In addition, the AC conductivity was also investigated. Hopping charge was considered as the main conduction mechanism at low temperature. As the temperature increases, small polarons and oxygen vacancies conduction played important roles. 相似文献
10.
11.
Huiling Guo Yang Li Yong Zhang Huajun Sun Xiaofang Liu 《Journal of Materials Science: Materials in Electronics》2018,29(22):19063-19069
The (1???2x)NBT–xKBT–xBT ternary piezoelectric system has been extensively studied in recent years. However, its electrical performance is far inferior to lead-based counterparts, and could not meet the requirements for practical applications. In this contribution, the 0.92NBT–0.04KBT–0.04BT (abbreviated as NKBT4) ceramics were prepared by traditional solid-state method. The effects of doped cobalt content on the structure and electrical performance of NKBT4 ceramics were studied systematically. The content of Co2O3 affects the average grain size, maximum dielectric constant, piezoelectric properties and the ferroelectric responses of the ceramics. It was found that the introduction of cobalt did not affect the phase structure of the ceramics, but is beneficial for the improvement of the dielectric and piezoelectric properties. When x?=?0.2, the piezoelectric coefficient (d33) is around 130 pC/N, which is greatly improved compared to pure NKBT4 ceramics. Besides, a relatively high dielectric constant (εr?=?1150) was obtained at the same composition. This work paves a new way for the further development of high performance lead-free piezoelectric ceramics. 相似文献
12.
Xiao Yan Xiuli Chen Xiaoxia Li Gaofeng Liu Hailin Zhang Huanfu Zhou 《Journal of Materials Science: Materials in Electronics》2018,29(6):4538-4546
(1 ? x)(K0.5Na0.5)NbO3–xBi(Mg0.75Mo0.25)O3 [(1 ? x)KNN–xBMM] (x?=?0.005, 0.01, 0.02) ceramics were prepared via a solid-state reaction method. X-ray diffraction patterns (XRD) and Raman spectrum showed that a solid solution was formed between the BMM and KNN, which improved the electrical properties of KNN. With increasing the BMM content, the grain firstly increased and then decreased. When x?=?0.01, the ceramics exhibited the optimized microstructure, indicating that there exits an optimal doping component. Temperature dependence of relative permittivity also increases firstly and then decreases. The relative permittivity (εr) of ~?1418 in stabilization zone, εmax?~?4861 at the Curie temperature T C ~ 394 °C, good temperature stability ?ε/ε123 °C?≤?±?15% from 123 °C to 348 °C, and the dielectric loss tanδ?≤?0.036 from 109 to 348 °C were obtained for 0.99KNN-0.01BMM ceramics. Conductivity behavior of the (1 ? x)KNN–xBMM was investigated as a function of temperature from 420 to 520 °C and frequency from 40 to 106 Hz, showing that the basic mechanisms of conduction and relaxation processes were thermally activated, and oxygen vacancies were the possible ionic charge transport carriers at higher temperatures. 相似文献
13.
E. D. Politova A. V. Mosunov D. A. Strebkov N. V. Golubko G. M. Kaleva B. A. Loginov A. B. Loginov S. Yu. Stefanovich 《Inorganic Materials》2018,54(7):744-748
We have studied the phase formation, microstructure, and dielectric and ferroelectric properties of (Na0.5–xBi0.5)TiO3 and (Na0.5Bi0.5 + x)TiO3 nonstoichiometric ceramics with Na/Bi < 1 and x = 0–0.1. The grain size of the ceramics has been shown to decrease with increasing x. The temperature dependences of dielectric permittivity for the samples studied have anomalies near ~400 K and peaks at ~600 K, corresponding to ferroelectric phase transitions. The phase transitions near 400 K demonstrate relaxor behavior, indicative of the presence of polar regions in a nonpolar matrix, as supported by laser second harmonic generation measurements. In addition, the (Na0.5Bi0.5 + x)TiO3 samples with x > 0.05 have anomalies near 900 K, confirming the presence of Bi4Ti3O12 as an impurity phase, which is accompanied by an increase in the spontaneous polarization of these samples. 相似文献
14.
Querui Hu Yiping Wang Lei Wu Jiang Yin Lang Chen Guoliang Yuan Ying Yang 《Journal of Materials Science: Materials in Electronics》2018,29(21):18036-18044
Piezoelectric ceramics xLiNbO3–yBiScO3–(1?x?y)PbTiO3 (LN–BS–PT, 0.00?≤?x?≤?0.10, 0.30?≤?y?≤?0.36) were synthesized and their phase diagram and morphotropic phase boundary between rhombohedral and tetragonal phases have been confirmed. The optimal properties were found at the composition of 0.03LN–0.36BS–0.61PT with piezoelectric coefficient d33* value of 702 pm/V, d33 of 551 pC/N, planar electromechanical coupling factor kp of 0.51, remnant polarization Pr of 46.5 µC/cm2, Curie temperature Tc of 337 °C, and a large strain of 0.351% at an electric field of 50 kV/cm and frequency of 2 Hz with a low strain hysteresis of 5.9%. The Curie temperature of the ternary system presents a linear relationship with LiNbO3 and BiScO3 contents. The optimization of these electric properties was probably ascribed to the enhancement in domain walls and the improving mobility of domain switching due to LiNbO3 doping. 相似文献
15.
Pan Ruan Peng Liu Bao-chun Guo Feng Li Zhi-fen Fu 《Journal of Materials Science: Materials in Electronics》2016,27(5):4201-4205
The ZnO–Nb2O5–xTiO2 (1 ≤ x ≤ 2) ceramics were fabricated by reaction-sintering process, and the effects of TiO2 content and sintering temperature on the crystal structure and microwave dielectric properties of the ceramics were investigated. The XRD patterns of the ceramics showed that ZnTiNb2O8 single phase was formed as x ≤ 1.6 and second phase Zn0.17Nb0.33Ti0.5O2 appeared at x ≥ 1.8. With the increase of TiO2 content and sintering temperature, the amount of the second phase Zn0.17Nb0.33Ti0.5O2 increased, resulting in the increase of dielectric constant, decrease of Q × f value, and the temperature coefficient of resonant frequency (τ f ) shifted to a positive value. The optimum microwave dielectric properties were obtained for ZnO–Nb2O5–2TiO2 ceramics sintered at 1075 °C for 5 h: ε r = 45.3, Q × f = 23,500 GHz, τ f = +4.5 ppm/°C. 相似文献
16.
E. A. Bikyashev I. V. Lisnevskaya M. G. Prusakova V. G. Maslennikov 《Inorganic Materials》2007,43(8):910-915
We report the first fluorine doping of lead magnesium niobate in the PbMg (1 + x)/3Nb(2 ? x)/3O3 ? x F x system in a wide composition range, x = 0.025 to 0.625. The fluorine content of the samples is shown to be substantially lower than the intended one because of the fluorine volatilization in the form of HF during synthesis and sintering in air. The ceramics consist of magnesium and lead oxides undetectable by x-ray diffraction, and a perovskite phase whose composition can be represented by the formula PbMg(1 + m)/3Nb(2 ? m)/3O3 ? m F m , where the fluorine content after sintering is m ≤ 0.12. The PbO and MgO contents of the ceramics depend on the starting mixture composition (x) and heat-treatment conditions (hydrogen fluoride and lead oxide volatilization). As a result of the low fluorine content, the diffraction patterns of the samples show no superlattice reflections, and their lattice parameter varies insignificantly with x. Data are presented on the temperaturedependent dielectric permittivity of ceramic samples sintered and annealed under different conditions. 相似文献
17.
A. G. Belous O. V. Ovchar A. V. Kramarenko B. Jancar J. Bezjak D. Suvorov 《Inorganic Materials》2007,43(3):277-280
We have studied the formation of zinc niobate, ZnNb2O6, with the columbite structure and the microstructure and microwave dielectric properties of Zn1+x Nb2O6+x ceramics. The results demonstrate that, in the range 0.005 ≤ x ≤ 0.03, the excess zinc reduces the porosity of the material and increases its microwave quality factor Q. For x ≥ 0.03, the Q of the ceramics decreases because of the formation of an additional, zinc-enriched phase. Sintering in an oxygen atmosphere is shown to improve the dielectric properties of stoichiometric ZnNb2O6. 相似文献
18.
Gaofeng Liu Xiuli Chen Guisheng Huang Dandan Ma Huanfu Zhou 《Journal of Materials Science: Materials in Electronics》2017,28(5):3931-3935
In this paper, (1 ? x)(K0.5Na0.5)NbO3–xBi(Mg0.75W0.25)O3 (x = 0–0.015) lead-free dielectric ceramics were investigated. XRD analysis certified that the Bi(Mg0.75W0.25)O3 has diffused into (K0.5Na0.5)NbO3 to fabricate a new solid solution. The addition of Bi(Mg0.75W0.25)O3 depressed the orthorhombic–tetragonal phase transition temperature from 210 to 176 °C and tetragonal–pseudocubic phase transition temperature (Curie point) from 419 to 400 °C. As x = 0.005, the ceramics exhibited high relative permittivity (ε ~ 1325), low dielectric loss (tan δ < 2.9%) tan δ stability (Δε/ε168°C ≤ ±15%) in the temperature range of 168 ~ 369 °C. Especially, the ceramics also showed optimized piezoelectric constant (d 33 = 122 pC N?1) and remnant polarization (Pr = 32.57 μC cm–2). These results indicated that the BMW added ceramics have potential applications in ferroelectric and thermal stability devices. 相似文献
19.
Ekaphan Swatsitang Krissana Prompa Thanin Putjuso 《Journal of Materials Science: Materials in Electronics》2018,29(15):12639-12651
In this work, the nominal CaCu3?xMgxTi4.2O12 (0.00, 0.05 and 0.10) ceramics were prepared by sintering pellets of their precursor powders obtained by a polymer pyrolysis solution method at 1100 °C for different sintering time of 8 and 12 h. Very low loss tangent (tanδ)?<?0.009–0.014 and giant dielectric constant (ε′) ~?1.1?×?104–1.8?×?104 with excellent temperature coefficient (Δε′) less than ±?15% in a temperature range of ??60 to 210 °C were achieved. These excellent performances suggested a potent application of the ceramics for high temperature X8R and X9R capacitors. It was found that tanδ values decreased with increasing Mg2+ dopants due to the increase of grain boundary resistance (Rgb) caused by the very high density of grain, resulting from the substitution of small ionic radius Mg2+ dopants in the structure. In addition, CaCu3?xMgxTi4.2O12 ceramics displayed non-linear characteristics with the significant enhancements of a non-linear coefficient (α) and a breakdown field (Eb) due to Mg2+doping. The high values of ε′ (14012), α (13.64) and Eb (5977.02 V/cm) with very low tanδ value (0.009) were obtained in a CaCu2.90Mg0.10Ti4.2O12 ceramic sintered at 1100 °C for 8 h. 相似文献
20.
L. G. Sevastyanov P. E. Kazin O. V. Kravchenko O. K. Gulish M. E. Leonova V. A. Stupnikov V. K. Genchel’ B. M. Bulychev 《Inorganic Materials》2009,45(7):748-753
The properties of magnesium diborides with the composition Mg1 ? x M x B2, where M = Al, Ga, In, and Tl, and Mg (B1 ? x E x ), where E = N, P, and Si (0.05 ≤ x ≤ 0.3), made by sintering of calculated amounts of boron, magnesium, and a substituent element or by a solid-phase exchange reaction of a corresponding halogenide of a metal with MgB2 at 1070–1170 K are studied. Using RFA technique, it is shown that, from all employed heterosubstituents, only the atoms of aluminum, gallium, and silicon in the amount x ≤ 0.2 are incorporated into magnesium and boron sublatticies. Here, the temperature of the superconducting transition T c = 39 ± 1K determined for pure magnesium diboride hardly changes. 相似文献