The surface morphology of flux-grown PbTiO3 crystals is examined by atomic force microscopy (AFM) at room temperature. Surface undulations due to a and c domains are observed on as-grown and heated crystals. The surface bending angle at 90° a-c domain walls is measured to be (3.58°±0.05°) in good agreement with the theoretical value, 3.6°. Footprints of ancient domains are found to be overlapped by surface undulations of the actual domain after polishing and heating process. Reciprocal 180° domains embedded in a and c domains are observed by both AFM and by polarizing optical microscopy on etched crystals. Details of the etched pattern are explored. Contrary to abrupt changes of height at 180° walls in c domains, only very small grooves are detected at 180° walls in a domains.
Magnetoelectric ͑ME͒ effect has been studied in a structure of a magnetostrictive TbFe 2 alloy, two piezoelectric Pb͑Zr, Ti͒O 3 ͑PZT͒ ceramics, and two nonmagnetic flakes. The ME coupling originates from the magnetic-mechanical-electric transform of the magnetostrictive effect in TbFe 2 and the piezoelectric effect in PZT by end bonding, instead of interface bonding. Large ME coefficients of 10.5 and 9.9 V cm −1 Oe −1 were obtained at the first planar acoustic and third bending resonance frequencies, which are larger than that of conventional layered TbFe 2 / PZT composites. The results show that the large ME coupling can be achieved without interface coupling. © 2011 American Institute of Physics. ͓doi:10.1063/1.3574004͔Magnetoelectric ͑ME͒ materials have stimulated tremendous fundamental and practical interests due to their potential applications in the fields of sensors, actuators, and transducers. [1][2][3][4] Hereinto, layered ME composites exhibit excellent ME effect at room temperature compared to single phase materials and multiphase bulk composites. [5][6][7][8][9] The ME effect in layered ME composites is a product property of the magnetostrictive and piezoelectric effects. For most investigations on layered ME composites, the classical structure is laminated with layers by interface bonding. A magnetic field applied to the layered ME composites will induce strain in the magnetostrictive layer which is passed along to the piezoelectric layer by interface coupling, where it induces an electric polarization. 10 Therefore, the interface coupling is a key factor that determines the ME coupling of layered composites. 11 However, in practice, there is no ideal interface for layered ME composites, which reduces the ME coupling.Large ME effect is not limited to be produced by interface coupling between magnetostrictive and piezoelectric phases, but will rather appear in the case when a magnetic force can mechanically act on a piezoelectric phase. Recently, the extrinsic ME effect was realized in multiphase magnet-piezoelectric composites which is not influenced by interface condition. [12][13][14][15] In this work, we report a large ME coupling obtained from a structure mechanically mediated by a stretching force and made up of a magnetostrictive TbFe 2 flake, two piezoelectric Pb͑Zr, Ti͒O 3 ͑PZT͒ flakes, and two nonmagnetic flakes. The proposed structure features an improved stretching stress coupling between the TbFe 2 and PZT flakes. And it is simple and more similar to the classical one than the multiphase magnet-piezoelectric composites, 12-15 which is advantageous for practical applications.The proposed ME structure, as shown in Fig. 1͑a͒, is made up of a magnetostrictive TbFe 2 flake, two piezoelectric PZT flakes, and two nonmagnetic ͑glass͒ flakes. The TbFe 2 flake was prepared by arc melting under argon atmosphere with dimensions of 15ϫ 6 ϫ 3.5 mm 3 ͑l ϫ w ϫ t͒. The commercial PZT flakes were sliced with dimensions of 15ϫ 6 ϫ 0.6 mm 3 and polarized along the thickness direction. Their dielectric, piez...
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