Origin and magnitude of the large piezoelectric response in the lead-free (1- x )BiFeO 3 - x BaTiO 3 solid solution
- PDF / 454,340 Bytes
- 9 Pages / 584.957 x 782.986 pts Page_size
- 24 Downloads / 169 Views
chanisms and magnitudes of the large piezoelectric response observed in lead-free (1–x) BiFeO3–xBaTiO3 (BFBT) ceramics are investigated. Preceding studies reported significant strain hysteresis and hard ferroelectric behavior in BFBT leading to a small low-field piezoelectric coefficient, instability of the poled domain state, and rapid degradation of piezoelectric properties. The current investigation shows that under application of a suitable direct current (dc) bias to stabilize the ferroelectric phase low- and high-field piezoelectric coefficients (d33) of 150 pC/N and 250 pC/N are observed for the composition 0.67BiFeO3–0.33BaTiO3 + 0.1 wt% MnO with a Curie temperature of 605 °C. Such enhancement of electromechanical properties under dc bias is in contrast to the expected behavior in traditional piezoelectric materials such as soft lead zirconate titanate (PZT). The large piezoelectric coefficients confirm strong intrinsic and extrinsic contributions to the piezoelectric response in BFBT, which coupled with high ferroelectric Curie temperature TC . 500 °C, suggests BFBT-based materials as promising lead-free alternatives to PZT piezoceramics.
I. INTRODUCTION
Separately, the structure and properties of barium titanate (BT) and bismuth ferrite (BF) have been widely studied.1–5 The discovery of the process for poling BT led to development of the first polycrystalline piezoelectric ceramics.1,2 Despite large piezoelectric coefficients in BT ceramics (d33 . 700 pC/N achieved in grain-oriented BaTiO3 with submicron domain size6) its application for piezoelectric actuators is limited due to multiple polymorphic phase transformations (PPT) and low Curie temperature (TC 5 130 °C). BF is a rhombohedral perovskite with a large local spontaneous polarization (PS 5 100 lC/cm2) and high Curie temperature (TC 5 870 °C).7–9 BF has been extensively studied due to the potential to exploit the multiferroic properties reported in this system. Both bulk and thin film BF materials have been developed, which simultaneously exhibit ferroelectric and ferromagnetic properties.8–10 It has been speculated that these materials could be used in high-density nonvolatile memory applications. In practice, however, low direct current (dc) electrical resistivity (attributed to the presence of the multivalent Fe cation) generally leads to difficulty in experimental observation of ferroelectric switching and the inability to pole bulk BF ceramics. Bulk ceramic bismuth ferrite-barium titanate (BFBT) solid solutions have previously been shown to form an extensive perovskite solid solution.11,12 The room tema)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2010.44 J. Mater. Res., Vol. 26, No. 1, Jan 14, 2011
http://journals.cambridge.org
Downloaded: 02 Jul 2014
perature symmetry of the perovskite phase is reported to be rhombohedral at low BT content, switching to cubic at ~0.30 mol fraction BT, and eventually becoming tetragonal for BT content greater than 0.92 mol.11,13,14 As in pure BF, processing difficulties and po
Data Loading...
