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1.
    
Ca0.6(Li0.5Bi0.5-xPrx)0.4Bi2Nb2O9 ceramics were prepared via a solid-state reaction method. The effect of the Pr content on the structural and electrical properties was systematically investigated. X-ray diffraction (XRD) combined with Rietveld refinement and X-ray photoelectron spectroscopy (XPS) demonstrated that a moderate amount of Pr3+ can be incorporated into the NbO6 octahedra, while excess Pr3+ ions probably enter into the (Bi2O2)2+ layers, thus resulting in an increase in the tetragonality of the crystal structure. The introduction of Pr suppressed the generation of oxygen vacancies and improved the preferential grain growth along the c-axis, which might be responsible for enhancing the resistivity (ρ ~ 106 Ω cm at 600°C). The replacement of Pr3+ for A-site Bi3+ enhanced the piezoelectric property, and the piezoelectric constant d33 increased from 13.8 pC/N to 16.3 pC/N. The high depolarization temperature (up to 900°C) implied that CBN-LBP100x ceramics are promising candidates for ultrahigh-temperature application.  相似文献   

2.
    
Bismuth layer–structured ferroelectric calcium bismuth niobate (CaBi2Nb2O9, CBN) is considered to be one of the most potential high-temperature piezoelectric materials due to its high Curie temperature Tc of ∼940°C, but the drawbacks of low electrical resistivity at elevated temperature and low piezoelectric performance limit its applications as key electronic components at high temperature (HT). Herein, we report significantly enhanced dc electrical resistivity and piezoelectric properties of CBN ceramics through rare-earth element Tb ions compositional adjustment. The nominal compositions of Ca1−xTbxBi2Nb2O9 (abbreviated as CBN-100xTb) have been fabricated by conventional solid-state reaction method. The composition of CBN-3Tb exhibits a significantly enhanced dc electrical resistivity of 1.97 × 106 Ω cm at 600°C, which is larger by two orders of magnitude compared with unmodified CBN. The donor substitutions of Tb3+ ions for Ca2+ ions reduce the oxygen vacancy concentrations and increase the band-gap energy, which is responsible for the enhancement of dc electric resistivity. The temperature-dependent dc conduction properties reveal that the conduction is dominated by the thermally activated oxygen vacancies in the low-temperature region (200–350°C) and by the intrinsic conduction in the HT region (350–650°C). The CBN-3Tb also exhibits enhanced piezoelectric properties with a high piezoelectric coefficient d33 of ∼13.2 pC/N and a high Tc of ∼966°C. Moreover, the CBN-3Tb exhibits good thermal stabilities of piezoelectric properties, remaining 97% of its room temperature value after annealing at 900°C. These properties demonstrate the great potentials of Tb-modified CBN for high-temperature piezoelectric applications.  相似文献   

3.
    
CaBi2Nb2O9 (CBN), one of the bismuth-layered structural ferroelectrics, with high Curie temperature (TC), has great potential in high-temperature applications. In this work, high Curie temperature and piezoelectric constant (d33) are realized in modified CaBi2Nb2O9 ceramics with Ce-substitution. Ce-substitution changes the crystal structures and domain structures of CBN-based ceramics, so as to improve the piezoelectric properties. The optimal performances are obtained with a high d33 value (∼18.0 pC/N) and a TC value (∼930°C), together with a low tan δ value (∼0.028 at 500°C). Moreover, the thermal stability is also enhanced, where the d33 value maintains 93.9% of its original value after annealing at 900°C for 2 h. Thus, these findings play a meaningful role in devices manufacturing, where the apply temperature is often more than 500°C.  相似文献   

4.
    
Phase boundaries (PBs) are known to contribute to the outstanding performances of lead-based and lead-free materials. However, a lack of PBs restricts the promotion of piezoelectric performance in bismuth layer-structured ferroelectrics (BLSFs). In this work, a pseudo PB, ie, pseudotetragonal distortion (regulated by Ce), is proposed to promote the piezoelectric properties of CaBi2Nb2O9-based ceramics, and an excellent piezoelectric constant (d33) of 20.2 pC/N with a high Curie temperature of 923°C is obtained. Verified Ce incorporation into the (Bi2O2)2+ layer alters the environment of the (Bi2O2)2+ layer, thereby influencing the atomic displacement in the Nb-O octahedron and modulating the theoretical spontaneous polarization (Ps). Strengthening of the pseudotetragonal distortion is favorable to the polarization switching, and maintains the theoretical Ps of ceramics at a high level, thus realizing the promotion of d33. Furthermore, pseudotetragonal distortion guarantees good thermal depoling performance of the ceramic, which remains at 89.6% (18.1 pC/N) of its initial d33 after depoling at 875°C. This work provides clear guidance on obtaining high d33 and good thermal stability in BLSFs.  相似文献   

5.
    
High-performance piezoelectric ceramic materials are required for piezoelectric sensors under harsh conditions in nuclear power plants, aeronautics, and aerospace. In this work, a lead-free high-Curie-temperature (TC ∼792°C) Aurivillius-type sodium bismuth niobate, Na0.5Bi2.5Nb2O9 (NBN), was fabricated through spark plasma sintering (SPS). The textured NBN ceramics with a high orientation factor of 83% exhibit significantly enhanced piezoelectric performance with a piezoelectric constant d33 of 31.2 pC/N, three times higher than that of nontextured NBN (d33 ∼ 11.6 pC/N). More importantly, the textured NBN ceramics maintain excellent electrical properties at high temperature, with a high in situ d33 of 35.9 pC/N, very low dielectric loss tanδ = 2.5% (@ 100 kHz) and high dc electrical resistivity ρ of 7.5 MΩ cm at 500°C. These results suggest that the textured NBN ceramics are good high-temperature piezoelectric ceramic materials, and have promising applications in the field of high-temperature piezoelectric sensors.  相似文献   

6.
采用传统固相法制备了(1-x)Ba(Mg1/3Nb2/3)O3-xMg4Nb2O9[(1-x)BMN-xM4N2,x=0.003～0.125]微波介质陶瓷,研究了相结构、烧结性能与介电性能随x的变化规律.结果表明:BMN与M4N2可以两相共存,且二者间存在有限固溶,BMN的烧结温度及高温稳定性有所降低.随着x的增大,介...  相似文献   

7.
采用固相法制备了BaTiO3基无铅PTCR陶瓷,通过加入Na0.5Bi0.5TiO3作为移峰剂来提高居里点,同时采用不同方式引入施主掺杂剂Nb2O5来降低室温电阻率。对陶瓷的XRD物相分析、SEM微观形貌分析和PTCR性能测试,结果表明引入Nb2O5方式会对BaTiO3基陶瓷的晶胞参数、微观形貌和室温电阻率产生很大影响。随着Nb2O5摩尔浓度的增加,室温电阻率先迅速减小,然后逐渐增大,而且当Nb2O5摩尔含量为0.2mol%时,室温电阻率最小。掺入0.2mol%Nb2O5和3.0mol%Na0.5Bi0.5TiO3时,BaTiO3基陶瓷的室温电阻率为3830Ω.cm,Tc为142℃,PTC突跳幅度为3个数量级。  相似文献   

8.
采用传统固相烧结法,制备了CaBi4Ti(1-x)NbxO1(5x=0.00-0.05,CBT-N)系铋层状结构无铅压电陶瓷。研究了Nb5+掺杂对CBT压电陶瓷压电与介电性能的影响。研究结果表明:添加Nb5+离子,改善了CBT陶瓷的烧结特性,提高了瓷体的致密度。Nb2O5的引入降低了CBT系列陶瓷的介质损耗,改善了陶瓷的压电与介电性能。当掺入量x=0.04(CaBi4Ti0.96Nb0.04O15)时制备的CBT基铋层状压电陶瓷具有优异的压电性能:d33=14pC/N,Qm=3086,εr=212,tanδ=0.0041,kt/kp=1.681。  相似文献   

9.
采用传统固相法制备了无铅压电陶瓷Bi0.5(Na0.825K0.175)0.5TiO3+xFe2O3(x为质量分数,0、0.1%、0.3%、0.5%、0.7%、1.0%、1.5%)(简写BNKTF-x),利用X射线衍射(XRD),和扫描电子显微镜(SEM)等分析表征了该体系陶瓷的结构、介电与压电性能。XRD测试表明,在1 180℃、2 h的烧结条件下,当铁的质量分数小于1.0%时,陶瓷呈现单一相的钙钛矿结构。所有陶瓷晶粒大多呈四方晶形,晶界明显。增加铁的含量有利于晶粒生长。此外,铁的加入也使陶瓷样品气孔率降低,当铁的质量分数在0.3%左右时陶瓷的致密性最好。BNKTF-0.1%体系陶瓷具有较好的电学性能:d33=145 pC/N,kp=0.28,εr=869,tanδ=0.032,Qm=106。  相似文献   

10.
采用固相烧结法制备了Na 1掺杂的CaBi4Ti4O(15CBT)铋系层状钙态矿无铅介电陶瓷。利用XRD、SEM和宽频LCR数字电桥分析了掺杂量、烧结温度等因素对CBT陶瓷晶相、微观形貌及介电性能的影响。研究表明,采用860℃预烧,保温3小时,1150℃终烧,保温1h的烧结工艺,Na2xCa1-xBi4Ti4O15(x=8mol%)的介电陶瓷致密性好、结晶性好,具有良好的介电性能。  相似文献   

11.
利用常规烧结方法制备出了多种A位离子掺杂的钛酸铋纳[(Bi1/2Na1/2)TiO3,BNT]无铅压电陶瓷.对BNT基陶瓷的电学性能和力学性能进行了研究.在(1-x)(Bi1/2Na1/2)0.900Ba0.088Sr0.012TiO3-x(Bi1/2K1/2)TiO3(x=0-0.14)陶瓷体系中,当x=0.10时,可获得最大压电常数(168pC/N).在1 kHz,这种陶瓷的介电常数、介电损耗和平面机电耦合系数分别为1 221,0.0361和0.2281.Curie温度随x的增加先增加,当x=0.12时,达到最高值(300℃),随后,当x值进一步增加,Curie温度降低.该种无铅压电陶瓷的Vickers硬度和断裂韧性分别为5.0GPa和2.0MP·m1/2,均高于Pb(Zr,Ti)O3陶瓷.  相似文献   

12.
Effects of 0.5 wt% CuO addition on the sintering, structural and electrical properties of perovskite layer structured (PLS) Sr2Nb2O7 ceramics prepared by solid‐state reaction method are investigated. The addition of CuO is beneficial to the liquid phase bridge formation at sintering process, leading to lower sintering temperature of 1180°C and larger bulk density up to 98%. Meanwhile, CuO modified Sr2Nb2O7 ceramics show a remarkable d33 of (1.1 ± 0.1) pC/N while still with a very high Tc of (1340 ± 2)°C. Raman spectra indicate that the improvement of piezoelectricity could be attributed to the rotation and/or distortion of oxygen octahedron caused by possible Cu2+ substitution at the A‐sites of Sr2Nb2O7.  相似文献   

13.
The processing conditions, reaction mechanism, fine structure of the powders, microstructure, and dielectric properties of SrBiNb2O9 (SBN) were systematically studied. A relative density of >80% was obtained using a two-step sintering process at moderate pressure. XRD showed that a single phase with the layered perovskite structure of SrBi2Nb2O9 (SBN) was formed after calcining at 600 °C. No intermediate phase was found during heat treatment at and above 600 °C. The crystallite size (D) and the effective strain (η) were found to be 38.8 nm and 0.01475, respectively, while the particle size obtained from TEM was laid between 25 and 36 nm. SEM revealed that the average grain size after sintering at 900 °C for 4 h was 0.67 μm. Dielectric constant and corresponding tangent loss were measured in the frequency range from 1 kHz to 1 MHz from which the Curie temperature (Tc) was found to be at 450 °C.  相似文献   

14.
    
Nb self-doped Bi3Ti1-xNb1+xO9 (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1) high-temperature piezoelectric ceramics were fabricated through the conventional solid-state sintering method. The effects of different Nb self-doping levels on the microstructure, piezoelectric activities, and electrical conduction behaviors of these Nb self-doped Bi3Ti1-xNb1+xO9 ceramics were studied in detail. Large doping level effects on piezoelectric activity and resistivity were confirmed, which might be ascribed to the evolution of the crystal structure and the variations of the oxygen vacancy concentration and the grain anisotropy induced by Nb doping. An optimized piezoelectric coefficient (d33) of 11.6 pC/N was achieved at x = 0.04 with a Curie temperature of 906°C. Additionally, an improved DC resistivity of 6.18 × 105 Ω·cm at 600°C was acquired in this ceramic. Furthermore, the ceramic exhibited excellent thermal stability with the d33 value maintaining 95% of its initial value after being annealed at 850°C for 2 hours. These results showed that Nb self-doped Bi3Ti1-xNb1+xO9 ceramics might have great potentials for high-temperature piezoelectric applications.  相似文献   

15.
High-temperature multilayer actuators based on Cu doping 0.367BiScO3–0.633PbTiO3 ceramic slices and Ag electrodes were prepared by low-temperature co-firing technology. The 0.3 wt% CuO addition has effectively reduced the sintering temperature of the ceramic from ~1080 to 930°C, thus the multilayer actuator were sintered at 930°C which is lower than the Ag melting point, that is, 961°C. The 4.3 mm thick multilayer actuator is composed of a series of ~44-μm-thick ceramic slices and ~2-μm-thick Ag electrodes. As a result, a ≥0.13% strain with nm-scale preciseness can be produced in the actuator by 200 V driving voltage not only at room temperature but also at a high temperature up to 200°C. This actuator is essential for industrial machinery that requires nm-scale position control at 20-200°C.  相似文献   

16.
    
High-temperature piezoelectric sensing is usually used in the aerospace, automotive, and power plant fields. High temperature piezoelectric ceramics are considered the key materials in these fields. In this paper, Ca1−x(Ba1/2Sr1/2)xBi2Nb1.985(W3/4Mn1/4)0.015O9 (x = 0.05, 0.10, 0.15 and 0.20) (C1−xBSxBNWM) has been synthesized by a traditional solid state reaction method. The effects of substitution of calcium at the A-site by barium and strontium on phase evolution and piezoelectric properties of the CaBi2Nb2O9 orthorhombic Aurivillius phases were investigated. The crystal structure of piezoelectric ceramics was characterized by XRD, Rietveld refinement, and Raman spectroscopy. Co-substitution of barium/strontium (Ba2+/Sr2+) and tungsten/manganese (W6+/Mn4+) resulted in lattice distortion of C1−xBSxBNWM ceramics. The results induce that the tetragonal crystal structure increase with increasing the co-substitution cations. Isothermal impedance spectroscopy confirmed intrinsic thermally activated conduction in the system. The C1−xBSxBNWM ceramics with x = 0.15 exhibit a very high Curie temperature (TC ∼ 923°C), a reasonable piezoelectric coefficient (d33 = 13.3 pC/N). Remarkably, even after thermal annealing at temperatures up to 800°C, it still retains a high d33 of 13 pC/N. In addition, the C0.85BS0.15BNWM ceramic had a relatively high resistivity (3.82 × 106 Ω·cm, 500°C). The Ca0.85(Ba1/2Sr1/2)0.15Bi2Nb1.985(W3/4Mn1/4)0.015O9 ceramics make possible their application in high-temperature acceleration transducers.  相似文献   

17.
研究了V2O5对Mg4Nb2O9陶瓷的烧结温度、相结构和微波介电性能的影响.结果表明,添加1％～8％的V2O5,能使该陶瓷的烧结温度降低到1000～1050℃而对其微波介电性能的影响很小,材料的主晶相为有序型刚玉结构的Mg4 Nb2O9,存在Mg4Nb2O6和Mg5Nb4O15杂相而没有检测到V2O5的存在.陶瓷的密度对微波介电性能起着决定性作用,介电常数e1与密度成线性关系(在99.99％的置信限内,其相关系数为0.98252),Q·f值与密度的关系较复杂.添加1％的v2O5,将Mg4Nb2O9陶瓷的烧结温度降低到了1050℃,得到了εr=12.72,Q·f=151040GHz的优异性能.  相似文献   

18.
采用固相法制备了Ce和Sr复合掺杂的Bi4Ti2.92Nb0.08O12.04(BTN+0.5x%CeO2+0.5x%SrCO3,0≤x≤1.5,质量分数)铋层状高温无铅压电陶瓷,研究了不同含量的Ce和Sr掺杂对BTN系陶瓷微观结构及电性能的影响。结果表明:样品均为单一的铋层状结构相,Ce和Sr的引入明显提高了陶瓷的压电性能。当掺杂量x=0.9时,样品具有最佳性能:压电常数d33=29pC/N,平面机电耦合系数kp=8.77%,介电损耗tanδ=0.13%,剩余极化强度Pr=15.87μC·cm-2和Curie温度TC=627℃。此外,该组分陶瓷样品具有良好的压电稳定性,表明该材料在高温领域下具有良好的应用前景。  相似文献   

19.
    
Novel BaCa2M3O9 (M = Si, Ge) microwave dielectric ceramics were prepared via solid-state reaction with sintering at 1125°C–1275°C for 5 h. Single-phase BaCa2M3O9 (M = Si, Ge) ceramics were obtained according to stoichiometry. The single-phase BaCa2Ge3O9 ceramic was confirmed through Rietveld refinement and high-resolution transmission electron microscopy/selected area electron diffraction and synthesized for the first time. The BaCa2M3O9 (M = Si, Ge) exhibited a triclinic structure with a P 1 ¯ $bar 1$ space group and good microwave dielectric properties. The εr, Q × f, and τf values of BaCa2M3O9 (M = Si, Ge) ceramics are mostly dominated by the relative density, ionic polarizability, relative covalence, and bond energy of M–O bond, respectively. A high Q × f value (61 800 GHz at 16.3 GHz) was obtained in BaCa2Ge3O9 ceramic due to its high rc (Ge–O) and low intrinsic dielectric loss. The BaCa2Si3O9 ceramic exhibited small |τf| value (‒36.4 ppm/°C) due to its large ESi-O. Excellent microwave dielectric properties (εr = 8.31, Q × f = 61 800 GHz, and τf = ‒58.7 ppm/°C) were obtained for the BaCa2Ge3O9 ceramic.  相似文献   

20.
    
Lead-free Aurivillius phase BaBi2Nb2O9 powders were prepared by solid-state reaction. Ferroelectric measurements on BaBi2Nb2O9 (BBNO) ceramics at room temperature provided supporting evidence for the existence of polar nanoregions (PNRs) and their reversible response to an external electric field, indicating relaxor behavior. The photocatalytic degradation of Rhodamine B reached 12% after 3 hours irradiation of BBNO powders under simulated solar light. Silver (Ag) nanoparticles were photochemically deposited onto the surface of the BBNO powders and found to act as electron traps, facilitating the separation of photoexcited charge carriers; thus, the photocatalytic performance was significantly improved. The present study is the first examination of the photochemical reactivity of a relaxor ferroelectric within the Aurivillius family with PNRs.  相似文献   

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