Materials Science and Engineering B 163 (2009) 179–183 Contents lists available at ScienceDirect Materials Science and Engineering B journal homepage: www.elsevier.com/locate/mseb Short communication Cerium-modified Aurivillius-type sodium lanthanum bismuth titanate with enhanced piezoactivities Chun-Ming Wang ∗ , Liang Zhao, Jin-Feng Wang ∗ , Li-Mei Zheng, Juan Du, Ming-Lei Zhao, Chun-Lei Wang School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, PR China article info Article history: Received 17 February 2009 Received in revised form 3 May 2009 Accepted 24 May 2009 PACS: 77.84.-s 77.84.Dy 77.65.Bn 77.80.Bh 77.80.Dj Keywords: Ferroelectrics Piezoelectric materials abstract The electrical, piezoelectric and dielectric properties of cerium-modified Aurivillius-type sodium lan- thanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) ceramics were investigated. It was found the piezoelectric activities of NLBT ceramics were significantly improved by cerium modification. The piezo- electric coefficient d 33 and Curie temperature T c for the 0.50 wt.% cerium-modified NLBT were found to be 29 pC/N and 573 ◦ C, respectively. The reasons for piezoelectric activities improvement by cerium modifi- cation were given. A small dielectric abnormity was observed in NLBT ceramics, which can be suppressed by cerium modification. © 2009 Elsevier B.V. All rights reserved. 1. Introduction The Aurivillius-type bismuth layer-structured ferroelectric (BLSF) ceramics first studied by Aurivillius [1] are widely known to possess a structure expressed by the general formula of (Bi 2 O 2 ) 2+ (A m-1 B m O 3m+1 ) 2- , where A is a mono-, di-, and tri-valent ion (e.g. Na + ,K + , Ca 2+ , Ba 2+ , Pb 2+ , or Bi 3+ ) or combination of them allowing dodecahedral coordination, B is a transition element (Ti 4+ , Nb 5+ , Ta 5+ ,W 6+ ) or combination of cations well suited to octahedral coor- dination, and m is an integer which represents the number of BO 6 octahedra in pseudo-perovskite (A m-1 B m O 3m+1 ) 2- layers between the (Bi 2 O 2 ) 2+ layers. The pseudo-perovskite (A m-1 B m O 3m+1 ) 2- layers interleave with (Bi 2 O 2 ) 2+ layers along the c-axis of the Aurivillius-type BLSFs. The pseudo-perovskite-like layers offer large possibilities in terms of compositional flexibility, the cation sites in the interleave (Bi 2 O 2 ) layers are occupied by Bi 3+ cations forming (Bi 2 O 2 ) 2+ slabs. The Aurivillius-type BLSFs have received significant attention for their potential use in nonvolatile ferroelectric random-access mem- ory (NvRAMs), owing to their fatigue-free properties [2–4]. The BLSFs also present relatively low dielectric constant, low aging rate, strong anisotropic electromechanical coupling factors and low tem- ∗ Corresponding authors. Tel.: +86 531 8837 7035x8322; fax: +86 531 8837 7031. E-mail addresses: wangcm@sdu.edu.cn (C.-M. Wang), wangjf@sdu.edu.cn (J.-F. Wang). perature coefficient of resonant frequency. These features, together with their high Curie temperature (T c ), make BLSFs attractive in high temperature and high frequency resonance applications [5–7]. Recently, considerable efforts have been devoted to the enhance- ment of piezoelectric properties of high temperature BLSFs [8–13]. However, it is difficult to achieve high piezoelectric activity in ordinary sintered BLSF ceramics with randomly oriented grain structure, due to their plate-like grains and spontaneous polar- ization restricted to lying in the a–b-plane. As a consequence of the anisotropy of the microstructures and properties, the piezo- electric activities of BLSF ceramics in directions parallel to the a–b-plane can be significantly enhanced by texturing technologies, such as hot-forging (HF), templated grain growth (TGG), and spark plasma sintering (SPS). However, the conductivity in the plane of the maximum piezoelectric activity is higher than that in the per- pendicular axis, which makes the poling process difficult, and also limits the integration in devices at high temperature in which con- ductivity increases [14]. Furthermore, it is desirable to obtain high piezoelectric activities and high electromechanical properties BLSF piezoelectric ceramics by conventional sintering method, from the point of view of commercial applications. It has been reported that A-site modification is more effective than B-site modification in enhancing the ferroelectric and piezo- electric properties of BLSFs, because B-site cations are similar in size and do not play a major structural role in the polarization process for BLSFs [15–17]. In the present work, A-site cerium- modified Aurivillius-type sodium lanthanum bismuth titanate 0921-5107/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.mseb.2009.05.019