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1.
Synthesis and properties of multiferroic BiFeO3 ceramics 总被引:1,自引:0,他引:1
Qing-hui Jiang Ce-wen Nan Yao Wang Yu-heng Liu Zhi-jian Shen 《Journal of Electroceramics》2008,21(1-4):690-693
BiFeO3 was synthesized using a modified sol–gel process, i.e., so-called Pechini method, as evidenced by X-ray diffraction pattern. Optimal conditions for the synthesis of single-phase BiFeO3 ceramics were obtained. This Pechini technique developed in this work is expected to be useful in synthesis of doped BiFeO3 or BiFeO3-based solid solution. Conventional sintering and spark plasma sintering processes were used to fabricate BiFeO3 ceramics. Ferroelectric and magnetic loops were measured at room temperature. The ceramic sample shows a stable dielectric constant and low loss tangent between 100 Hz and 10 MHz. 相似文献
2.
Dariusz Bochenek Pawel Kruk Ryszard Skulski Pawel Wawrza?a 《Journal of Electroceramics》2011,26(1-4):8-13
We present the results of obtaining and investigating multiferroic ceramics Pb(Fe1/2Nb1/2)O3 (PFN) and PFN doped by various amounts of Li (PFN:Li). Ceramics have been obtained from oxides by two-step synthesis. For obtained samples the X-ray diffraction patterns, microstructure, DC electric conductivity, the temperature dependencies of dielectric permittivity and dielectric losses, electromechanical properties and hysteresis loops have been investigated. Obtained results have shown that the introduction of Li decreases electric conductivity and improves dielectric and electromechanical parameters important for applications. 相似文献
3.
In this study, to develop the optimal composition of ceramics for low loss piezoelectric actuator and ultrasonic motor applications, (K0.5Na0.5)(Nb0.97Sb0.03)O3?+?0.009 K5.4Cu1.3Ta10O29?+?0.1wt%Li2CO3?+?xwt%Bi2O3(x?=?0?~?0.9) lead-free piezoelectric ceramics with a fixed quantity of 0.009 K5.4Cu1.3Ta10O29 (abbreviated as KCT) were manufactured using the conventional solid-state solution processes. The effects of Bi2O3 addition on the dielectric and piezoelectric properties were then investigated. From the X-ray diffraction analysis result the specimens demonstrated orthorhombic symmetry when Bi2O3 was less 0.6?wt%, a pseudo-cubic phase appeared when Bi2O3 was 0.9?wt%. SEM images indicate that a small amount of Bi2O3 addition affect the microstructure. The piezoelectric properties of (K0.5Na0.5)(Nb0.97Sb0.03)O3 ceramics were greatly improved by a certain amount of Bi2O3 addition. Excellent properties of density?=?4.54?g/cm3, relative densities?=?98.5?%, k p?=?0.468, Q m?=?1,715 and d 33?=?183 pC/N were obtained with a composition of 0.3?wt% Bi2O3 相似文献
4.
5.
Pinyang Fang Huiqing Fan Laijun Liu Jin Chen Shaojun Qiu 《Journal of Electroceramics》2009,23(1):52-55
Ferroelectric ceramics, SrBi2Nb2O9 (SBN), Sr0.8Cu0.2Bi2Nb2O9 (SCBN) and Sr0.8K0.1Na0.1Bi2Nb2O9 (SKNBN) were prepared by a solid state reaction process. X-ray diffraction analysis shows that the alkali and Cu almost diffuse
into the SBN lattice to form a solid solution during sintering and some slight secondary phases was detected. The effect of
alkali and Cu on dielectric properties of the SBN ceramics was discussed. The dielectric loss factor of (K,Na) doped SBN ceramics
degraded considerably to 0.01 and their frequency and temperature stabilities were enhanced. The dielectric constant was enhanced
by approximately 60% and the Curie temperature (Tc) was also improved for Cu doped SrBi2Nb2O9 ceramics. 相似文献
6.
The effects of CuO and TiO2 additives on the microstructure and microwave dielectric properties of Al2O3 ceramics were investigated. Al2O3 ceramics with CuO and TiO2 additions can be well sintered to achieve 93∼98% theoretical densities below 1,360 °C due to Ti4Cu2O liquid phase sintering effect. The Qf values decreased with increasing CuO and TiO2 content, due to the formation of the second phase Ti4Cu2O. However, the varying behaviors of the dielectric constant (ɛ
r
) and temperature coefficients (τ
f
) were associated with phase constitutions, as a result of the change of CuO and TiO2content. The τ
f
can be shifted close to 0 ppm/°C by controlling the content of CuO and TiO2. The specimens with 0.5 wt.% CuO and 7 wt.% TiO2 sintered at 1,360 °C for 4 h showed ɛ
r
of 11.8, Qf value of 30,000 GHz, and τ
f
of −7 ppm/°C. 相似文献
7.
In the present study, a new procedure, arc-melting followed by spark plasma sintering, was employed to prepare BaTi2O5 ceramics with high relative density and large dimension. Single-phased BaTi2O5 powders were synthesized from BaCO3 and TiO2 powders by arc-melting, and then the BaTi2O5 powders were densified by spark plasma sintering at different temperatures (1273-1473?K) and pressures (20-50?MPa). Single-phased BaTi2O5 ceramic was obtained at and below 1423?K, however, it tended to decompose at elevated temperatures. Considering the upperbound decomposing temperature, we further enhanced the densification of BaTi2O5 ceramics by increasing the sintering pressure, and a high relative density of 92.1?% was achieved at 50?MPa. The permittivity of the BaTi2O5 ceramics was 28.7 at 1?MHz, and increased with the measuring temperature, reaching a maximum value of 191 at the Curie temperature of?~?740?K. 相似文献
8.
9.
Bi-based ceramics with pyrochlore structure exhibit interesting dielectric properties such as high dielectric constant and small dielectric loss at high frequency and low firing temperature. Structure and dielectric properties of non-stoichiometric ceramics Bi1.5?x ZnNb1.5O7?1.5x (with x?=??0.25~0.6) were investigated. The compounds departured from stoichiomeric compositions lead to structural parameters change. The second phase appeared when x?≥?0.4. The lattice parameters of cubic pyrochlore Bi1.5?x ZnNb1.5O7 and grain size decreased as x increased. The experimental results show that dielectric constant decrease with increasing of the x value. The dielectric relaxation and defect resulting from non-stoichiometric ceramics Bi1.5?x ZnNb1.5O7?1.5x were discussed. 相似文献
10.
Lidmila Burianova Stanislav Panos Martin C. Stennett Anthony R. West Ganesanpotti Subodh Mailadil T. Sebastian Stanislav Kamba 《Journal of Electroceramics》2010,25(2-4):116-121
In this paper, measurements of the nonlinear ferroelectric, piezoelectric and dielectric properties of Pb9Ce2Ti12O36 (Pb9CTO) and Ba2NdTi2Nb3O15 (BNTN) ferroelectric ceramics are presented. Hysteresis P(E) loops were measured as a function of applied electric field, frequency and temperature. The coercive field (E c) and remnant polarization (P r) displayed temperature and frequency dependence. Lead-free BNTN ceramics exhibited a coercive field E c?>?2.4 kV mm?1 and a piezoelectric coefficient d 33?=?2 pC N?1. The hysteresis loop was pinched above 110°C and a linear response was observed at 155°C, typical of a paraelectric material. Pb9CTO was shown to be ferroelectric with coercive field E c?=?1.2 kV mm?1 and a d 33?=?65 pC N?1. The frequency dependences of the impedance of the Pb9CTO discs were analyzed. 相似文献
11.
BiFeO3 nanofibers doped with Ba and Mn have been prepared by an electrospinning method. The influence of Ba doping on the phase composition, microstructure, photocatalytic properties was investigated detailedly. Our results indicate that with the increase of Ba doped contents, the formation of impurity phase can be suppressed in these BiFeO3 nanofibers. A crystal lattice transformation occurred when 15 % Ba was doped. The degradation of Congo Red proved the enhanced photocatalytic behaviors in visible light region can be observed in these BFO nanofibers. 相似文献
12.
Piezoelectric properties of Al2O3-doped Pb(Mn1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics were investigated. The constituent phases, microstructure, electromechanical coupling factor, dielectric constant,
piezoelectric charge and voltage constants were analyzed. Diffraction peaks for (002) and (200) planes were identified by
X-ray diffractometer for all the specimens doped with Al2O3. The highest sintered density of 7.8 g/cm3 was obtained for 0.2 wt% Al2O3-doped specimen. Grain size increased by doping Al2O3 up to 0.3 wt%, and it decreased by more doping. Electromechanical coupling factor, dielectric constant, piezoelectric charge
and voltage constants increased by doping Al2O3 up to 0.2 wt%, and it decreased by more doping. This might result from the formation of oxygen vacancies due to defects in
O2 − ion sites and the substitution of Al3+ ions. 相似文献
13.
Lei Zhang Jianxing Shen Jiaoxian Yu Hongshi Zhao Zhiliang Xiu Chunlei Yan Chuanshan Li Jinmei Dong Yuan Ma 《Journal of Electroceramics》2011,26(1-4):105-111
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
14.
The correlation between crystal structure and properties of x wt% SrCO3-4.5?wt.%Bi2O3-Ag(Nb0.8Ta0.2)O3 (x SrCO3-Bi2O3-ANT) (x?=?0.5?~?3.0) dielectric ceramics was investigated. The permittivity was significantly influenced by the redshift of three typical vibration modes of A1g(Ag), F2g(Nb/Ta) and A1g(O). The dielectric loss was optimized by the restraint of the second phase AgNbO3, and a minimum value was obtained when x?=?2.0. Changes of c/a value, which indicate the degree of lattice distortion, reflected the temperature coefficient of relative permittivity (τε) was highly correlated with the crystal structure and a near zero τε value was achieved with 2.0?wt.% Sr concentration. The Bi2O3-doped ANT ceramics containing 2.0?wt.% SrCO3 sintered at 1150°C showed excellent dielectric properties: an εr value of 841, a tan δ value of 0.00119 and a near zero (?23.7?ppm/°C) τε value. 相似文献
15.
The effects of V2O5 and Li2CO3 on the sinterability and microwave dielectric properties of Mg4Nb2O9 (MN) ceramics were investigated. With addition of 1.5wt% V2O5, the dielectric constant (?) and Q·? value of MN ceramics sintered at 1,000 °C are comparable to those of pure MN sintered at 1,400 °C. The good results are because of the enhancement of the density by liquid sintering at the lower temperatures. With the mixtures of V2O5 and Li2CO3, the sintering temperature of MN was further reduced to 925 °C at the expense of the quality factor (Q·?) value. Typically, ? of 13.7 and Q·? value of 78,000 GHz were obtained for the specimens with mixtures of 1.5wt% V2O5 and 1.5wt% Li2CO3 and sintered at 925 °C for 5 h. 相似文献
16.
Fang Wang 《Integrated ferroelectrics》2018,188(1):96-102
ABSTRACTBiFeO3-LaY2Fe5O12 (BFO-LYIG) composites and the corresponding flexible films were prepared via solid-sate reaction and spin coating respectively. The composites were used for structures and magnetic properties characterization, while the flexible films were used for multiferroic properties measurement. The results show that the BFO and LYIG phases can coexist in the composite with no impurity phase for certain mole ratio, but with obvious impurity phases for other mole ratios. Compared to the weak magnetic and ferroelectric property of BFO, the magnetization and polarization of the composites can be simultaneously improved due to the high magnetization and resistivity of LYIG. 相似文献
17.
《Integrated ferroelectrics》2013,141(1):475-487
(1 ? x)PbMg1/3Nb2/3O3-(x)PbSc1/2Nb1/2O3 (PMN-PSN) solid solution crystals have been grown by the flux method in the whole concentration range. X-ray supercell reflections due to B-cation ordering were observed for as-grown crystals from the 0.1 ≤ x ≤ 0.65 compositional range. Though the ordered domains are rather large (~50 nm) the relaxor-like dielectric behavior is observed for compositions with x < 0.6. The diffusion of the dielectric permittivity maximum in as-grown crystals is the lowest at x = 0.6 and increases towards the end members of solid solution. Such behavior is explained within a Bragg-Williams approach by employing the random layer model. At x ~ 0.6 the excitation energy determined from the Vogel-Fulcher relation exhibits a jump which we regard to changing the kind of the polar regions from PbMg1/3Nb2/3O3 to PbSc1/2Nb1/2O3 related type. 相似文献
18.
Juhyun Yoo Jungmin Hwang Sangho Lee Kwanghyun Chung Hyunggyu Lee 《Journal of Electroceramics》2006,17(2-4):525-529
In this study, in order to develop the composition ceramics for multilayer piezoelectric actuator, PNN substituted PMN-PZT
ceramics were fabricated using Li2CO3 and Na2CO3 as sintering aids, and their piezoelectric and dielectric characteristics were investigated. With the increase of the amount
of PNN substitution, dielectric constant (εr), electromechanical coupling factor (k
p), and piezoelectric constant (d
33) of specimens showed the maximum value at each sintering temperature, and crystal structure changed from tetragonal to rhombohedral.
At the sintering temperature of 950∘C, the density, εr, k
p, d
33, Qm and Tc of 12 mol% PNN substituted PMN-PNN-PZT composition ceramics showed the optimal values of 7.79 g/cm3, 1160, 0.599, 419pC/N, 894 and 332∘C, respectively, for low loss multilayer piezoelectric actuator application. 相似文献
19.
In this study, crystalline structure, dielectric and impedance properties of SrBi2Ta2O9 (SBT) - based ferroelectric ceramics have been investigated with the substitution of wolframium/tungsten (W) onto the tantalum
site. Wolframium doped SrBi2(W
x
Ta1 − x
)2O9 (0.0 ≤ x ≤ 0.20) ceramics were synthesized by solid state reaction method. The X-ray diffractogram analysis revealed that the substitution
formed a single phase layered perovskite structure for the doping content up to x ≤ 0.05. The dielectric measurements as a function of temperature show an increase in Curie temperature (T
c
) over the composition range of x = 0.05 to 0.20. The W6 + substitution in perovskite-like units results in a sharp dielectric anomaly at the ferroelectric phase transition. Furthermore,
the dielectric constant at their respective Curie temperature increases with wolframium doping. Both enhanced Curie temperatures
and dielectric constants at the Curie points indicate an increase in polarizability, which could be attributed to the increased
“rattling space” due to the incorporation of the smaller tungsten cations. The dielectric loss reduces significantly with
tungsten addition. AC impedance properties vis-à-vis wolframium content has also been studied. 相似文献
20.
Toshihiro Fukushima Kazuaki Kato Shuzo Ohsumi Tadashi Takenaka 《Electrical Engineering in Japan》1994,114(2):82-92
Recently, one type of thermal-type IR detector, the pyroelectric sensor, has become of great interest in commercial applications, because of its ability to operate without cooling, its constant detectivity independent of wavelength, and its low cost. The conventional pyroelectric materials are usually normal ferroelectric materials with a first and second phase transition. The working temperatures are sufficiently below the Curie temperature Tc for stable responsivity to temperature. Electric field induced-type pyroelectric sensors have also been proposed. Relaxor ferroelectric materials such as Pb(Mg1/3Nb2/3)O3 (PMN) and Pb(Sc1/2Ta1/2)O3 (PST), which have a glassy Curie temperature near room temperature, are used in this type of sensor. This paper describes the sensor properties of electric field induced-type pyroelectric sensors prepared by using PMN and PST ceramics as compared with the conventional type sensors. Material evaluations of PMN and PST ceramics were made to determine their dielectric and pyroelectric properties. PMN shows excellent induced pyroelectric properties for the sensors over a wide range of temperatures. On the other hand, PST seems to be inadequate for an IR detector because of a very narrow high-response temperature range. The sensors with PMN and PST ceramics show enhanced pyroelectric activities under dc bias field. The measured sensor voltage responsivities agree with the calculated values for the PMN case. The electric field induced-type infrared sensor with thick or thin film materials seems to be satisfactory as linear array IR detectors for thermal imaging, with application of a higher electric field. 相似文献