Improvement of microwave dielectric properties of Ba 2 Ti 9 O 20 ceramics using [Zn 1/3 Nb 2/3 ] 4+ substitution for Ti
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Improvement of microwave dielectric properties of Ba2Ti9O20 ceramics using [Zn1/3Nb2/3]4+ substitution for Ti4+ Qihang Yang1 · Ting Luo1 · Tao Yu1 · Hongtao Yu1 · Jingsong Liu1 Received: 29 May 2020 / Accepted: 22 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Ba2[Zn1/3Nb2/3]xTi9−xO20 (x = 0–0.5) ceramics with high-quality factors were successfully prepared via traditional solid-state method. In this work, the microstructure and microwave dielectric properties of the samples were studied. The X-ray diffraction patterns indicated that two different phases B aTi4O9 and B a2Ti9O20 existed at x = 0, while the phase of B a2Ti9O20 was found gradually dominating in specimens with the doping of [Zn1/3Nb2/3]4+. At the level of x = 0.5, a fraction of the monoclinic phases of B a2Ti9O20 were transformed into the triclinic phase. Furthermore, the SEM and relative density were used to confirm the homogeneous microstructure of the Ba2[Zn1/3Nb2/3]xTi9−xO20 ceramics. The doping of [Zn1/3Nb2/3]4+ can effectively improve the microwave properties of B a2Ti9O20 ceramics, which are shown as the increase of dielectric constant, quality factor, and the stability of temperature coefficient. Particularly, the excellent microwave dielectric properties were achieved for the Ba2[Zn1/3Nb2/3]0.3Ti8.7O20 ceramics sintered at 1300 °C, with εr ~ 39.3, a high Q × f ~ 43,879 at 6 GHz, and a τf ~ + 7 ppm/°C.
1 Introduction As the heart of the telecommunication, dielectric filters generally should possess the characteristics of miniaturization, high-frequency selection characteristic, and good temperature stability to meet the increasing requirements of microwave communication technology [1–3]. Especially, dielectric ceramics should exhibit high dielectric constant (εr), high-quality factor (Q × f), and near-zero temperature coefficient (τf) of resonant frequency at microwave frequency. Over the past decades, dielectric ceramics with various dielectric constants such as BaO–TiO2, MgO–CaO–TiO2, SnO2–ZrO2–TiO2, BaO–Ln2O3–TiO2, Li-based, Al2O3-based have been investigated to satisfy the different design requirements for resonators, filters, and antennas [4–8]. Among these materials, BaO–TiO2-based dielectrics have attracted a lot of concerns due to their * Hongtao Yu [email protected]; [email protected] * Jingsong Liu [email protected] 1
State Key Laboratory of Environment Friendly Energy Materials, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China
optimum microwave dielectric properties and low cost, of which Ba2Ti9O20 (B2T9) with εr ~ 39, Q × f 38,000 at 4 GHz, and a τf ~ + 2 ppm/°C is a preferred material for application in microwave field [9, 10]. However, the preparation of the B2T9 single-phase ceramics has been a challenge because of the coexistence of minor phases like BaTi4O9, BaTi5O11, and Ba4Ti13O30 which was mostly attributed to the extremely high calcining temperature employed for the reaction
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