Effects of Fe 2 O 3 addition on microstructure and piezoelectric properties of 0.2PZN-0.8PZT ceramics
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this work, the effect of Fe2O3 addition on the microstructure and piezoelectric properties of Pb(Zn1/3Nb2/3)0.2Ti0.4Zr0.4O3 (0.2PZN–0.8PZT) ceramics were investigated. The studies indicated that the solution limit of Fe2O3 in the lattice of perovskite structure was about 0.1 wt%. Phase analysis shows that small addition of doping Fe2O3 results in the phase evolution from rhombohedral to tetragonal, sharp decrease of the Curie temperature, and remarkable increase of the grain size. Meanwhile, Fe2O3 addition within the solution limit led to the increase of the ⑀r, kp, and d33. It is believed that the variation in the dielectric and piezoelectric properties are closely related to the microstructure change, phase evolution, and tetragonal distortion as Fe2O3 added.
I. INTRODUCTION
Lead zirconate titanate [Pb(Zr,Ti)O3, PZT] ceramics have been intensively studied because of their excellent piezoelectric properties, which can easily be tailored by substituting the ions at the A or B site of the ABO3 perovskite structure.1 Relaxor-type perovskites with A(BIB2)O3 structure, such as Pb(Mg1/3Nb2/3)O3 or Pb(Zn1/3Nb2/3)O3, exhibit excellent piezoelectric as well as dielectric properties. Among them, PZN is a typical relaxor, and its relative dielectric constant exceeds 5 × 104 at TC (140 °C).2 The addition of small amounts of such relaxor materials was found to be beneficial for the electrical properties of PZT-based ceramics due to the formation of fine and uniform rhombohedral domains along tetragonal ones.3–5 It is reported that the dielectric, piezoelectric, and ferroelectric properties of PZT can be adjusted over a wide range by changing the composition of PZN.6 Due to these advantages, PZN-PZT ceramics have drawn much interest in recent years. To meet the stringent requirements for specific applications, doping is a very effective approach to modifying the dielectric and ferroelectric properties of lead-based perovskites.7,8 It was observed that both the dielectric and piezoelectric properties of these PZT-relaxor materials are strongly influenced by the addition of other additives such as Nb, Ba, La, and Mn.7,9–13 Fe2O3 is probably one of the most frequently used acceptors in ferroelectrics. The effects of Fe2O3 on PZT a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2005.0339 2670
http://journals.cambridge.org
J. Mater. Res., Vol. 20, No. 10, Oct 2005 Downloaded: 12 Mar 2015
and PZT-based ternary ceramics have been studied.7,13 However, information regarding the effect of Fe2O3 addition on the ternary PZN-PZT was scarcely reported, even though the effect of Fe2O3 on microstructure and piezoelectricity in PZN-PZT ceramics should be investigated further. The purpose of this study was to investigate the effect of Fe modification on the piezoelectric properties of PZT-PZN ceramics for its potential application in piezoelectric transducers. Based on previous results for this system,14–16 0.2PZN–0.8PZT was selected as the starting composition. Specimens with this composition were f
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