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1.
使用溶胶-凝胶法原位制备了具有镶嵌结构的0-3型Na0.5Bi0.5TiO3-CoFe2O4(NBT-CFO)复相多铁性陶瓷,并研究了其电、磁性能。通过TG-DTA、XRD等表征手段研究了干凝胶的结晶过程,利用CFO与NBT的差异化结晶温度设计了分步煅烧结晶工艺并得到粒径45 nm的NBT-CFO纳米粉体,并烧结得到具有镶嵌结构0.9NBT-0.1CFO复相陶瓷,陶瓷中CFO晶粒均匀分布在NBT晶粒内部。与使用机械混合法制备的复相陶瓷相比,具有镶嵌结构的0.9NBT-0.1CFO复相陶瓷在250-1M Hz频率范围内的室温介电损耗均更低,250 Hz时其损耗只有前者的30%。介电温谱、阻抗谱与模谱分析表明具有镶嵌结构的复相陶瓷在350-650 oC温区内表现出由铁电-铁磁相界面极化造成的介电弛豫行为,其激活能为0.77 eV。镶嵌结构使复相陶瓷在室温下具有更大的剩余极化和更高的抗击穿场强,提高了其铁电性能。 相似文献
2.
Qing Xu Min Chen Wen Chen Han-Xing Liu Bok-Hee Kim Byung-Kuk Ahn 《Journal of Alloys and Compounds》2008,463(1-2):275-281
(Na0.5Bi0.5)0.93Ba0.07TiO3 ceramics added with 0.2 wt.% Ln2O3 (Ln = La, Pr, Eu, Gd) were prepared by a citrate method, and the structure and electrical properties of the ceramics were investigated with respect to the size of the lanthanide. All the specimens maintain a coexistence of rhombohedral and tetragonal phases in crystal structure, while no remarkable evolution in microstructure with the lanthanide addition was observed. Compared with (Na0.5Bi0.5)0.93Ba0.07TiO3, the lanthanide addition resulted in an increased diffuseness in phase transition and a decrease in depolarization temperature (Td). The variation in dielectric, piezoelectric and ferroelectric properties with the lanthanide addition presents an evident lanthanide size dependence. The addition of La2O3 or Pr2O3 tailored the electrical properties basically following a soft doping effect, with the specimens added with La2O3 and Pr2O3 attaining high piezoelectric constants (d33) of 188 and 184 pC/N, respectively. By contrast, the Eu2O3 or Gd2O3 addition led to an abnormal change in the electrical properties, which was qualitatively interpreted by an internal stress effect. 相似文献
3.
Jingbo Zhao Hongliang Du Shaobo QuJiafu Wang Hongmei ZhangYiming Yang Zhuo Xu 《Journal of Alloys and Compounds》2011,509(8):3537-3540
To improve the temperature stability of piezoelectric properties of Na0.5K0.5NbO3 (KNN)-based ceramics, Bi(Mg2/3Nb1/3)O3 (BMN) was used to modify Na0.5K0.5NbO3 (KNN)-based ceramics by a conventional sintering technique. Piezoelectric and ferroelectric properties of 0.99K0.5Na0.5NbO3-0.01Bi(Mg2/3Nb1/3)O3 ceramics were studied. It is found that 0.01BMN-0.99KNN ceramics exhibits stable piezoelectric properties as the temperature changes due to the composition fluctuation on B sites (d33 ≈ 130 pC/N, dielectric loss tg θ ≤ 5% in the range 25-300 °C). These results indicate that these materials are promising lead-free piezoelectric ceramic candidates for practical applications. 相似文献
4.
In this work, we report on the Pb(Mg1/3Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-Pb(Zr0.52Ti0.48)O3 (PMN-PZN-PZT) ceramics with Ba(W0.5Cu0.5)O3 as the sintering aid that was manufactured in order to develop the low-temperature sintering materials for piezoelectric device applications. The phase transition, microstructure, dielectric, piezoelectric properties, and the temperature stability of the ceramics were investigated. The results showed that the addition of Ba(W0.5Cu0.5)O3 significantly improved the sintering temperature of PMN-PZN-PZT ceramics and could lower the sintering temperature from 1005 to 920 °C. Besides, the obtained Ba(W0.5Cu0.5)O3-doped ceramics sintered at 920 °C have optimized electrical properties, which are listed as follows: (Kp = 0.63, Qm = 1415 and d33 = 351 pC/N), and high depolarization temperature above 320 °C. These results indicated that this material was a promising candidate for high-power multilayer piezoelectric device applications. 相似文献
5.
Piezoelectric and dielectric properties of Dy2O3-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free ceramics
Chen Zhi-hui Ding Jian-ning Mei LinYuan Ning-yi Zhu Yuan-yuan 《Journal of Alloys and Compounds》2011,509(2):482-485
(Bi0.5Na0.5)0.94Ba0.06TiO3 + x wt% Dy2O3 with x = 0-0.3 ceramics were synthesized by conventional solid-state processes. The effects of Dy2O3 on the microstructure, the piezoelectric and dielectric properties were investigated. X-ray diffraction pattern confirmed that the coexistence of tetragonal and rhombohedral phases in the (Bi0.5Na0.5)0.94Ba0.06TiO3 composition was not changed by adding 0.05-0.3 wt% Dy2O3. SEM images indicate that all the ceramics have pore-free microstructures with high density, and that doping of Dy2O3 inhibits the grain growth of the ceramics. The addition of Dy2O3 shows the double effects on decreasing the piezoelectric and dielectric properties for 0 < x < 0.15 when Dy3+ ions substitute B-site Ti4+ ions, and increasing the properties for 0.15 < x < 0.3 when Dy3+ ions enters into A-site of the perovskite structure. The optimum electric properties of piezoelectric constant d33 = 170 pC/N and the dielectric constant ?r = 1900 (at a frequency of 1 kHz) are obtained at x = 0.3. 相似文献
6.
XiaoMing Chen WenYue PanHuanHuan Tian XuXu GongXiaoBing Bian Peng Liu 《Journal of Alloys and Compounds》2011,509(5):1824-1829
0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (NBTB) and 0.05BiFeO3-0.95NBTB (BF-doped NBTB) lead-free ceramics were prepared by solid state reaction method. The ceramics were sintered at 1180 °C for 2 h in O2 and N2. All ceramics exhibited a single phase of perovskite structure. Relative amount of tetragonal phase was related to the sintering atmospheres. Both grain size and shape were influenced by the sintering atmospheres. Sintering the ceramics in N2 weakened their dielectric anomalies corresponding to the transition from ferroelectric phase to the so-called “intermediate phase”. When the NBTB and BF-doped NBTB ceramics were sintered in N2, their maximum dielectric constant and the degree of diffuseness of the transition from the “intermediate phase” to paraelectric phase increased, but their Curie temperatures decreased. The difference in dielectric properties of the ceramics sintered in different atmospheres was closely related to the difference in oxygen vacancy concentration. The correlation between ferroelectric properties and sintering atmospheres is associated with a competing effect among oxygen vacancy concentration, A-site vacancy concentration and percentage of tetragonal phase. 相似文献
7.
Wenzhong LuYing Wang Guifen Fan Xiaohong WangFei Liang 《Journal of Alloys and Compounds》2011,509(6):2738-2744
The structure, dielectric properties and phase transition of lithium and potassium modified Bi0.5Na0.5TiO3 ceramics were investigated widely. The phase transition behavior with respect to changes in composition and temperature was investigated using X-ray diffraction analysis, dielectric and ferroelectric characterizations. The experimental results show that there is a diffusion phase transition in (Na1−xKx)0.5Bi0.5TiO3 ceramics at Tm and the diffuseness of the phase transition is more obvious for the samples near the morphotropic phase boundary. In (Na1−xLix)0.5Bi0.5TiO3 system, due to the space charge polarization induced by ions conductivity, the low frequency permittivity increases so remarkably at high temperature that the peak of maximum permittivity vanishes. The hysteresis loops at different temperatures indicate that there is no existence of anti-ferroelectrics in lithium and potassium modified Bi0.5Na0.5TiO3 ceramics above the depolarization temperature Td. The depolarization reason is that the tetragonal nonpolar phase occurs and leads to the macro-micro domain transformation at about Td. 相似文献
8.
Maheshkumar L. Mane V.N. DhageSagar E. Shirsath R. SundarK. Ranganathan S.M. OakK.M. Jadhav 《Journal of Alloys and Compounds》2012,511(1):31-34
The polycrystalline spinel structured Li0.5Fe2.5O4 ferrite have been prepared by conventional double sintering ceramic method. The samples were palletized and irradiated by Nd:YAG laser with different laser fluencies and characterized by infrared spectroscopy and DC electrical resistivity in order to obtain phase, crystal structure and conduction mechanism in pristine and irradiated samples. The infrared spectroscopy is employed to study the local symmetry and conduction mechanism in crystalline solids before and after irradiation. The DC electrical resistivity measured by two-probe technique from room temperature to beyond Curie temperature with steps of 10 K increases after laser irradiation. Variation of dielectric properties like dielectric constant and dielectric loss tangent is also measured as a function of temperature. A significant reduction in the values of dielectric constant and dielectric loss tangent has been observed with the increase of laser dose. 相似文献
9.
Lingling WeiZupei Yang Rui GuXuejuan Yan Yongqiang Li 《Journal of Alloys and Compounds》2011,509(26):7247-7252
LiSbO3 doped Sr0.53Ba0.47Nb2O6 ceramics were synthesized by conventional mixed-oxide method. The phase structure, microstructure, dielectric and ferroelectric properties of obtained ceramics were investigated. Pure tungsten bronze structure could be obtained in all ceramics and LiSbO3 additive could promote densification and reduce the sintering temperature. The dielectric characteristics showed diffuse phase transition phenomena for all samples, which was proved by linear fitting of the modified Curie-Weiss law with γ value varying between 1.65 and 1.92. With increasing LiSbO3 content, the transition temperature Tc decreased gradually to near room temperature. Normal ferroelectric hysteresis loops could be observed in all compositions, but the remnant polarization (Pr) and coercive field (Ec) all decreased gradually. Besides, the underlying mechanism for variations of the electrical properties caused by LiSbO3 doping was explained in this work. 相似文献
10.
Yih-Chien Chen Sheng-Kai YangKuang-Chiung Chang 《Journal of Alloys and Compounds》2011,509(39):9518-9522
The microwave dielectric properties of La(Mg0.5−xNixSn0.5)O3 ceramics were examined with a view to their exploitation for mobile communication. The La(Mg0.5−xNixSn0.5)O3 ceramics were prepared by the conventional solid-state method at various sintering temperatures. The X-ray diffraction patterns of the La(Mg0.4Ni0.1Sn0.5)O3 ceramics revealed no significant variation of phase with sintering temperatures. Apparent density of 6.71 g/cm3, dielectric constant (?r) of 20.19, quality factor (Q × f) of 74,600 GHz, and temperature coefficient of resonant frequency (τf) of −85 ppm/°C were obtained for La(Mg0.4Ni0.1Sn0.5)O3 ceramics that were sintered at 1550 °C for 4 h. 相似文献
11.
The microwave dielectric properties and microstructures of (1 − x)La(Mg0.5Ti0.5)O3-x(Ca0.8Sr0.2)TiO3 ceramics, prepared by a mixed oxide route, have been investigated. The forming of solid solutions was confirmed by the XRD patterns and the measured lattice parameters for all compositions. A near zero τf was achieved for samples with x = 0.5, although the dielectric properties varied with sintering temperature. The Q × f value of 0.5La(Mg0.5Ti0.5)O3-0.5(Ca0.8Sr0.2)TiO3 increased up to 1475 °C, after which it decreased. The decrease in dielectric properties was coincident with the onset of rapid grain growth. The optimum combination of microwave dielectric properties was achieved at 1475 °C for samples where x = 0.5 with a dielectric constant ?r of 47.12, a Q × f value of 35,000 GHz (measured at 6.2 GHz) and a τf value of −4.7 ppm/°C. 相似文献
12.
采用传统固相反应合成法制备0.95(K0.5Na0.5)NbO3-0.05Li(Nb0.5Sb0.5)O3基无铅压电陶瓷,研究了烧结温度对0.95(K0.5Na0.5)NbO3-0.05Li(Nb0.5Sb0.5)O3陶瓷相结构、显微组织和压电介电性能的影响。结果表明,在960~1060℃的温度区间内,所得到的一系列烧结样品在室温下均为纯的钙钛矿型结构,未观察到第二相出现;随着烧结温度的升高,晶粒的平均尺寸显示出先增大后减小的趋势,在1020℃时晶粒的平均粒径达到最大值3.5μm。电学性能分析表明,烧结温度为1020℃时,该体系陶瓷压电介电性能达到最优值:d33=245pC/N,kp=0.42,tanδ=0.03,ε3T3/ε0=640,Ec=2.1kV/mm,Pr=20μC/cm2。 相似文献
13.
Muhammed TanYüksel Köseo?lu Furkan AlanErdo?an ?entürk 《Journal of Alloys and Compounds》2011,509(39):9399-9405
We report an orderly study on the structural and dielectric properties of Ni0.5Zn0.5Cr0.5Fe1.5O4 nanoparticles (NPs) synthesized by a polyethylene glycol (PEG)-assisted hydrothermal technique. XRD, FT-IR, FE-SEM and EDX measurements were implemented for the structural, morphological and compositional investigations of the product. Dielectric spectroscopy was used for the dielectric property investigation of the sample. Average particle size of the nanoparticles was estimated using Debye-Scherrer's equation as 34 nm. Electrical properties of the sample have been investigated in the range of 1 Hz to 3 MHz (233-412 K). It is observed that the sample has a giant dielectric constant approaching to 106 within the examined temperature range. It is also determined that the sample exhibits a dispersive phase transition around 305 K at which this giant value of dielectric constant has been obtained. This transition has been characterized by Diffuse Phase Transition. Temperature and frequency dependence of dielectric loss function has been attributed to surface charges for the short-time relaxations and to hopping electrons for the long-time relaxations. At low frequencies, dielectric loss function has been supported by the modified Cole-Cole equation. Frequency and temperature dependent conductivity behavior of the sample has been explained by Overlapping Large Polaron Tunneling model. 相似文献
14.
Sinterability and dielectric properties of Ba0.55Sr0.4Ca0.05TiO3-CaTiSiO5-Mg2TiO4 composite ceramics
Qianqian JiaHuiming Ji Xiaolei LiShan Liu Zhengguo Jin 《Journal of Alloys and Compounds》2011,509(41):10155-10160
The composite ceramics of Ba0.55Sr0.4Ca0.05TiO3-CaTiSiO5-Mg2TiO4 (BSCT-CTS-MT) were prepared by the conventional solid-state route. The sintering performance, phase structures, morphologies, and dielectric properties of the composite ceramics were investigated. The BSCT-CTS-MT ceramics were sintered at 1100 °C and possessed dense microstructure. The dielectric constant was tailored from 1196 to 141 as the amount of Mg2TiO4 increased from 0 to 50 wt%. The dielectric constant and dielectric loss of 40 wt% Ba0.55Sr0.4Ca0.05TiO3-10 wt% CaTiSiO5-50 wt% Mg2TiO4 was 141 and 0.0020, respectively, and the tunability was 8.64% under a DC electric field of 8.0 kV/cm. The Curie peaks were broadened and depressed after the addition of CaTiSiO5. The optimistic dielectric properties made it a promising candidate for the application of tunable capacitors and phase shifters. 相似文献
15.
Bi0.5Na0.5TiO3-BaTiO3-Bi0.5K0.5TiO3 (BNT-BT-BKT) lead-free piezoceramics with compositions near the rhombohedral-tetragonal morphotropic phase boundary (MPB) were prepared and investigated. At room temperature, all ceramics show excellent electrical properties. In this study, the best properties were observed in 0.884BNT-0.036BT-0.08BKT, with the remnant polarization, bipolar total strain, unipolar strain, piezoelectric constant, and planar electromechanical coupling factor being 34.4 μC cm−2, 0.25%, 0.15%, 122 pC N−1, and 0.30, respectively. Detailed analysis of the temperature dependence of polarization-electric field (P-E) loops and bipolar/unipolar strain-electric field (S-E) curves of this composition revealed a ferroelectric-antiferroelectric phase transition around 100 °C. Around this temperature, there is a significant shape change in both P-E and S-E curves, accompanied by enhanced strain and decreased polarization; the largest recoverable strain reaches 0.42%. These results can be explained by the formation of antiferroelectric order and the contribution of field-induced antiferroelectric-ferroelectric phase transition to piezoelectric response. Our results indicate that BNT-BT-BKT lead-free piezoceramics can have excellent electrical properties in compositions near the MPB and also reveal some insight into the temperature dependence of the electrical performance with the MPB composition. 相似文献
16.
Mingzhe Hu Chunya LuoHuyong Tian Haoshuang Gu 《Journal of Alloys and Compounds》2011,509(6):2993-2999
The phase evolution, crystal structure and dielectric properties of (1 − x)Nd(Zn0.5Ti0.5)O3 + xBi(Zn0.5Ti0.5)O3 compound ceramics (0 ≤ x ≤ 1.0, abbreviated as (1 − x)NZT-xBZT hereafter) were investigated. A pure perovskite phase was formed in the composition range of 0 ≤ x ≤ 0.05. The B-site Zn2+/Ti4+ 1:1 long range ordering (LRO) structure was detected by both XRD and Raman spectra in x ≤ 0.05 samples. However, this LRO structure became gradually degraded with an increase in x. The dielectric behaviors of the compound ceramic at various frequencies were investigated and correlated to its chemical composition and crystal structure. A gradually compensated τf value was obtained in (1 − x)NZT-xBZT microwave dielectrics at x = 0.03, which was mainly due to the dilution of dielectric constant in terms of Claussius-Mossotti differential equation. 相似文献
17.
Polycrystalline samples of BaFe0.5Nb0.5O3 and (1 − x)Ba(Fe0.5Nb0.5)O3-xSrTiO3 [referred as BFN and BFN-ST respectively] (x = 0.00, 0.15 and 0.20) have been synthesized by a high-temperature solid-state reaction technique. The XRD patterns of the BFN and BFN-ST at room temperature show a monoclinic phase. The microstructure of the ceramics was examined by the scanning electron microscopy (SEM) and shows the polycrystalline nature of the samples with different grain sizes, which are inhomogeneously distributed through the sample surface. Detailed studies of dielectric and impedance properties of the materials in a wide range of frequency (100 Hz-5 MHz) and temperatures (30-270 °C) showed that properties are strongly temperature and frequency dependent. Complex Argand plane plot of ?″ against ?′, usually called Cole-Cole plots is used to check the polydispersive nature of relaxation phenomena in above mentioned compounds. Relaxation phenomena of non-Debye type have been observed in the BFN and BFN-ST ceramics, as confirmed by the Cole-Cole plots. 相似文献
18.
Pure and chromium-doped CCTO (CaCu3Ti4O12) ceramics were prepared by a conventional solid-state reaction method, and the effects of chromium doping on the microstructures and electrical properties of these ceramics were investigated. Efficient crystalline phase formation accompanied by dopant-induced lattice constant expansion was confirmed through X-ray diffraction studies. Scanning electron microscopy (SEM) results show that doping effectively enhanced grain growth or densification, which should increase the complex permittivity. The dielectric constant reached a value as high as 20,000 (at 1 kHz) at a chromium-doping concentration of 3%. The electrical relaxation and dc conductivity of the pure and chromium-doped CCTO ceramics were measured in the 300-500 K temperature range, and the electrical data were analyzed in the framework of the dielectric as well as the electric modulus formalisms. The obtained activation energy associated with the electrical relaxation, determined from the electric modulus spectra, was 0.50-0.60 eV, which was very close to the value of the activation energy for dc conductivity (0.50 ± 0.05 eV). These results suggest that the movement of oxygen vacancies at the grain boundaries is responsible for both the conduction and relaxation processes. The short-range hopping of oxygen vacancies as “polarons” is similar to the reorientation of the dipole and leads to dielectric relaxation. The proposed explanation of the electric properties of pure and chromium-doped CCTO ceramics is supported by the data from the impedance spectrum. 相似文献
19.
Laijun Liu Huiqing Fan Shanming Ke Xiuli Chen 《Journal of Alloys and Compounds》2008,458(1-2):504-508
Phase structure, microstructure, dielectric and piezoelectric properties of 0.4 wt% CeO2 doped 0.94(Bi0.5Na0.5)TiO3–0.06BaTiO3 (Ce-BNT6BT) ceramics sintered in the temperature range from 1120 to 1200 °C have been investigated as a candidate for lead-free piezoelectric ceramics. Tetragonal phase played an important role in improvement of electrical properties and the density of the ceramics. Dielectric constant decreased slightly with the increase of sintering temperature in ferroelectric region but a reverse phenomenon occurred in antiferroelectric and paraelectric regions, suggesting that interfacial polarizations were improved with the increase of sintering temperature and domain walls of ferroelectricity became active after depolarization. At room temperature, Ce-BNT6BT ceramics sintered at 1180 °C showed good performances: dielectric constant was 914 at 1 kHz, thick coupling factor kt was 0.52, and the ratio of kt/kp was 2.3. The ceramics were suitable for narrowband filters and ultrasonic transducers in commercial applications. 相似文献
20.
Hong-fang ZhangSiu Wing Or Helen Lai Wa Chan 《Journal of Alloys and Compounds》2011,509(21):6311-6316
Fine-grained Pb(Zr0.53Ti0.47)O3-(Ni0.5Zn0.5)Fe2O4 (PZT-NZFO) magnetoelectric (ME) composite ceramics were fabricated by a modified hybrid process at a low sintering temperature of 900 °C. Well-controlled crystallized grain size and homogeneous microstructure with a good mixture of two phases were observed in the ceramics. The ceramics show coexistence of ferrimagnetic and ferroelectric phases with well-formed ferromagnetic and ferroelectric hysteresis loops at room temperature. A significant ME effect was observed with a ME coefficient of 0.537 V cm−1 Oe−1 in the vicinity of electromechanical resonance. In addition, high capacitance can be obtained at low frequency, and magnetic properties in the ceramics can be tailored by the grain size of the ferromagnetic particles in a simple and flexible way. 相似文献