蛙泳动作要领Preparation and characterization of (Ba0.88Ca0.12)( Zr0.12Ti0.88)O3 powders and ceramics produced by sol–gel process
Renbo Yang1,a, Weiguo Fu1,b, Xiangyun Deng1,2,c, Zhongwen Tan1, Yanjie Zhang1, Liren Han1, Cheng Lu1 and Xiaofen Guan1
1College of Physics and Electronic Information, Tianjin Normal University, Tianjin 300387, China
2 Key Laboratory of Ministry of Education for Application Technology of Chemical Materials in Hainan Superior Resources, Hainan Provincial Key Laboratory of Rearch on Utilization of Si-Zr-Ti Resources, Materials and Chemical Engineering Institute, Hainan University, Haikou 570228, China
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Keywords:(Ba0.88Ca0.12)( Zr0.12Ti0.88)O3 powders and ceramics; sol-gel process; piezoelectric properties
Abstract. The (Ba0.88Ca0.12)( Zr0.12Ti0.88)O3 powders and piezoelectric ceramics were prepared by sol-gel process. The reaction process was analyzed with the help of thermo gravimetric and differential scanning calorimetry. X-ray diffraction characterized results showed that the structure of the (Ba0.88Ca0.12)( Zr0.12Ti0.88)O3powders was perovskite structure and the particle size was approximately 37nm. Piezoelectric measurements revealed that Curie temperature and the maximum piezoelectric coefficient d33 is 95℃ and 215pm/V, respectively.
Introduction
BaTiO3-bad ceramic is one kind of important lead free Piezoelectric Ceramics, and it has been widely ud in military, atomic energy, aviation, metal, petrochemical complex fields.[1] The study of BaTiO3-bad lead-free piezoelectric ceramic has become a popular reaches field in the world in recent years. For instance, the barium zirconate titanate (BZT) piezoelectric ceramic[2], bismuth calcium titanate (BCT) piezoelectric ceramic[3], barium strontium titanate (BST) Piezoelectric ceramic[4] and so on. Tang and co-workers[2] had prepared Barium zirconate titanate ceramics by a sol–gel process. Li et al. [3] had prepared barium calcium titanate (BCT) powders and ceramics. In 2009, Wenfeng Liu and Xiaobing Ren[5] had prepared BZT-BCT with a conventional solid-state reaction method, they reported that the BZT-BCT ceramics have large Piezoelectric effect. However,
there are few reports about preparing the BZT-BCT using a sol-gel method. As is well-known, the sol–gel process has many advantages, such as relatively simple, low-cost process and stoichiometric compositions. [6]
In this study, our experiment group had prepared a ries of different stoichiometric compositions BZT-BCT Piezoelectric ceramics by sol–gel process. And then in this paper, we have studied the preparation and characterization of (Ba0.88Ca0.12)( Zr0.12Ti0.88)O3 powders and Piezoelectric ceramics, and have found that the Curie temperature (about 95℃) is lower than BaTiO3 (120℃), and the maximum piezoelectric coefficient d33 have reached 215pm/V already.
Experimental details
The (Ba0.88Ca0.12)(Ti0.88Zr0.12)O3powers were synthesized by the sol-gel process using Tetrabutyl orthotita[CH3(CH2)3O]4Ti (98.0%), barium acetate C4H6BaO4(99.0%) , calcium acetate Ca(CH3COO)2·H2O (98.0%) and zirconium oxynitrate ZrO(NO3)2·2H2O as starting materials. The synthesis procedure is as follows: the mixed solution A of 0.088 mol Barium acetate, 0.012mol
Calcium acetate, 32.4ml acetic acid glacial and 57ml distilled water was obtained by stirring at room医药外企
0.088 mol Tetrabutyl orthotita was dissolved in 35ml Ethanol absolute; the mixed solution B was prepared by mixing zirconium oxynitrate solution and Tetrabutyl orthotita solution. And followed by the mixed solution A was added by dropwi into the mixed solution B with stirring vigorously until the solution color changed from clear to pale white, i.e. the gel was formed at room temperature, this cour of reaction is about 0.5 hours. The gel was solidified after 4 hours; the xerogels were obtained by drying in a electric oven at 120℃for 12 hours. The xerogels were crystallized by annealing in air at 800 °C for 2 hours in a muffle furnace (Germany). After mixed with 4% PVA solution, the powders were compresd into discs of 10 mm diameter at around 30MPa and the discs were sintered at 1280℃ for 2 hours in the muffle furnace. After polishing, silver paste was coated on both sides of the sintered discs, and the discs were fired at 450℃ for 30 min to form electrodes.
The electrical properties were obrved using a tester of ferroelectric analysis 2000 (TF 2000, Germany). The crystal structures of (Ba 0.88Ca 0.12)( Ti 0.88Zr 0.12)O 3 powders and ceramics were determined by X-ray diffraction (XRD).
Fig.1 shows the sintering curves of the (Ba 0.88Ca 0.12)( Ti 0.88Zr 0.12)O 3 powders and the heating rate is 10℃/min, and then nature cooled to the ambient atmosphere. The sintering curves of (Ba 0.88Ca 0.12)(Ti 0.88Zr 0.12)O 3 piezoelectric ceramic is displayed in Fig.2, where temperature rate is controlled at 10℃/min too, the end gment of curve corresponding to nature cooling. However, the difference, showed in Fig.2, consists in heat treatment at 500℃ for 30 min for the samples, which was Results and Discussions
Thermal analysis of the (Ba 0.88Ca 0.12)( Ti 0.88Zr 0.12)O 3 xerogels. Fig. 3 shows the TG and DS
C curves of the (Ba 0.88Ca 0.12)( Ti 0.88Zr 0.12)O 3 xerogels. As shown in TG curve, the total weight loss of the xerogel is 63.25%. The weight loss process of the xerogels were divided into three steps in the TG curve. The first step of weight loss occurs at 40-310℃, which can be attributed to dehydration of the xerogels and volatilization of the residual organic compounds.[7] For this reason, the weight loss is continuous with the ri of temperature. The cond step of weight loss is 310-540℃, corresponding to exothermic reaction peak (approximately 318℃) in the DSC curve, which can be attributed to decomposition of titanyl acetate into TiO 2, ZrO 2 and acetic anhydride.[8] The last step appears in a broad temperature range from 540 to 800℃, leading to a weight loss of approximately
2.24%, and corresponding to exothermic reaction peak(approximately 500℃) in the DSC curve. This weight loss may result from the formation of (Ba 0.88Ca 0.12)( Ti 0.88Zr 0.12)O 3 and the relea of CO 2 via the reaction between BaCO 3, CaCO 3, TiO 2 and ZrO 2.[9]
Fig.3 TG & DSC curves of the xerogels
清华同方笔记本XRD Analysis. Fig.4 shows the XRD patterns of the (Ba 0.88Ca0.12)( Ti 0.88Zr 0.12)O3 powders (annealed at 800℃ for 2h). It can be en that all the peaks corresponding to the perovskite structure. Moreover, using Scherrer formula,
)cos (θλB k D = (1)
where D is the size of powders,λ is the X-ray wavelength, B is the FWHM (full width at half maximum) of diffraction peak, θ is the diffraction angle, and bad on the half-width of (1 1 0) reflection of the obrved X-ray data, the particle size of the (Ba 0.88Ca 0.12)( Ti 0.88Zr 0.12)O 3 powders can the (Ba 0.88Ca 0.12)( Zr 0.12Ti 0.88)O 3 ceramics at room temperature, and the frequency of 10 Hz, the voltage of 5500V. The maximum polarization (Pm ), spontaneous polarizatio
n (Ps ), remanent polarization (Pr ) and coercive electric field (Ec ) of the (Ba 0.88Ca 0.12)( Zr 0.12Ti 0.88)O 3 ceramics were found to be 5.08µC/cm 2, 4.25µC/cm 2，1.39µC/cm 2and 2.64kVcm −1, respectively.
)O 3 ceramic at room temperature. It can be en that the dielectric constant is approximately 2588 at the room temperature. Fig.7 shows the temperature dependence of the dielectric constant measured for (Ba 0.88Ca 0.12)( Zr 0.12Ti 0.88)O 3 ceramics. The (Ba 0.88Ca 0.12)( Zr 0.12Ti 0.88)O 3 ceramics exhibits abrupt changes in relative permittivity, which is normal for ferroelectric be
havior.[11] The Curie temperature T C from ferroelectric pha to paraelectric pha occurs at 95℃, which is consistent with previous works, [5,12] However, the Curie temperature of BCTZ ceramics are lower than the pure
Fig. 8 shows piezoelectric displacement curve of (Ba0.88Ca0.12)( Zr0.12Ti0.88)O3 ceramic at a driving frequency of 10 Hz and at room temperature. And Fig.9 shows the d33-E loop of the ceramic. The maximum piezoelectric coefficient d33reaches 215pm/V exhibited by Fig.9. Meanwhile, the d33 value is 217pm/V through calculating on the slope of the piezoelectric displacement curve, which is well consisted with the value acquired from Fig.9.
Conclusions
The crystal structure of (Ba0.88Ca0.12)( Ti0.88Zr0.12)O3ceramics prepared by sol-gel process is perovskite, and the particle size is approximately 37nm. Curie temperature is approximately 95℃, and the dielectric constant is approximately 2588 at the room temperature. Especially, the maximum piezoelectric coefficient d33 had reached 215pm/V, which means that the effect of piezoelectricity of this material is excellent.
References
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[2] X.G. Tang et al.: Acta Materialia. Vol.52 (2004), p.5177
[3] L.Y. Li, X.G. Tang: Materials Chemistry and Physics. Vol.115 (2009), p.507
享受[4] Q.X. Liu et al.: Materials Chemistry and Physics. Vol.112 (2008), p.281
[5] Wenfeng Liu, and Xiaobing Ren: Physical Review Letters Vol. 103(2009), p. 257602
[6] X.G. Tang, K.H. Chew et al.: Appl. Phys. Lett.. Vol. 85 (August 2004), p.991
[7] F. Du et al.: Materials Rearch Bulletin. Vol. 44 (2009), p.1931
[8] Wei Li, Zhijun Xu et al.: Journal of Alloys and Compounds. Vol.10 (2009), p.1016
[9] Q.L. Li, S.T. Chen, P. Yao et al.: Acta Physi-Chim. Vol. 16 (2000), p.174
[10] B. Cui et al.: Journal of Alloys and Compounds. Vol. 459 (2008), p.591
[11] Y.F. Chang, Z.P.Yang, et al.: Appl. Phys. Lett. Vol.90 (2007), p. 232905
[12] S.W. Zhang et al.: Journal of the European Ceramic Society. Vol. 29 (2009), p. 3240
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doi:10.4028/www.scientific/AMR.148-149
Preparation and Characterization of
(Ba<sub>0.88</sub>Ca<sub>0.12</sub>)(Zr<sub>0.12</sub>Ti<sub>0.88</sub>)O<s ub>3</sub> Powders and Ceramics Produced by Sol-Gel Process
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