Preparation and microwave dielectric properties of Bi 2 Ti 4 O 11 ceramics
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Preparation and microwave dielectric properties of Bi2Ti4O11 ceramics Baojian Fu • Yingchun Zhang • Ming Hong Fan Jiang • Jiangli Cao
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Received: 14 January 2013 / Accepted: 9 April 2013 Ó Springer Science+Business Media New York 2013
Abstract Single phase of Bi2Ti4O11 ceramics, which belong to meta-stable phase compounds, were synthesized by controlling the reaction time through conventional solid-state method. The effects of annealing time on phase composition of Bi2Ti4O11 ceramic powders and sintered ceramics were studied by XRD analysis. Second phase Bi2Ti2O7 appeared when the annealing time shorter than 4 h. However, pure phase of Bi2Ti4O11 powders can be formed by prolonging the annealing time to 6 h at 1,000 °C. The sintering temperatures on microstructure and microwave dielectric properties of Bi2Ti4O11 ceramics were investigated. The results show that ceramics sintered at 1,075–1,175 °C are single phase of Bi2Ti4O11 and present two different sizes of prismatic shape grains. Smaller size crystals grow into larger ones with increasing sintering temperature. The ceramics sintered at 1,125 °C reach a maximum density and have a microwave dielectric properties of er = 51.2, Q 9 f = 3,050 GHz and sf = -297 ppm/°C.
1 Introduction With the fast growth of microwave communication in the past decades, there is an ever-increasing demand for lowcost and high-performance dielectric ceramics. Which are key materials for the manufacturing of microwave components such as resonators, filters, oscillators, wave guides and antennas [1]. The properties required for high
B. Fu Y. Zhang (&) M. Hong F. Jiang J. Cao School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, People’s Republic of China e-mail: [email protected]
performance dielectric ceramics are high dielectric constant (er), high quality factor (Q 9 f) and near zero temperature coefficient of resonant frequency (sf) [2]. Therefore, light weight and low cost ceramics attracting the component manufacturers’ attention and a large number of dielectric has been developed [3]. In the low-cost Bi2O3– TiO2 system, several compounds, such as Bi4Ti3O12, Bi2Ti2O7, Bi12TiO20 and Bi2Ti4O11, have been found and most of them have special electronic properties [4–6]. Furthermore, due to the low sintering temperature and high relative dielectric constant, these compounds have potential electronic devices applications. Several researchers have attempted to prepare Bi2Ti4O11 ceramics and investigate their properties. The polymorphism and dielectric properties at 1 MHz of Bi2Ti4O11 was studied by Subbarao in 1962 [7]. Single crystal of Bi2Ti4O11 with platelike and prismatic shape were prepared by Barsukova et al. [8]. Using different staring materials and process, the microwave dielectric properties of Bi2O3–Bi2Ti4O11 composite ceramics were researched by Axelsson and co-workers [9]. Akimov studied the effect of pressing pressures and heating rate on the synthesis and sintering of Bi2Ti4O11. And found that the formation of
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