Elastic, dielectric and electromechanical properties of (Bi0.5Na0.5) TiO3-BaTiO3 piezoceramics at the morphotropic phase boundary region

JOURNAL OF ALLOYS AND COMPOUNDS

卷:690

Article

Machado, Rodrigo^1,2  dos Santos, Valdeci B.^1,3  Ochoa, Diego A.¹  Cerdeiras, Elena⁴  Mestres, Lourdes⁴  Garcia, Jose E.¹ 

[1] Univ Politecn Catalunya BarcelonaTech, Dept Fis, Barcelona 08034, Spain

[2] Univ Nacl Rosario, Inst Fis Rosario, RA-2000 Rosario, Argentina

[3] Univ Fed Piaui, Coordenacao Engn Mat, BR-64049550 Teresina, Brazil

[4] Univ Barcelona, Dept Quim Inorgan & Organ, Seccio Quim Inorgan, Barcelona 08028, Spain

关键词: Ceramics;    Ferroelectrics;    Dielectric response;    Piezoelectricity;   

DOI  :  10.1016/j.jallcom.2016.08.116

来源: Elsevier

【 摘 要 】

A systematic study of the functional properties of the (1-x)(Bi-0.Na-5(0).(5))TiO3-xBaTiO(3) (BNT-xBT) piezoceramic system for 0.05 <= x <= 0.07 is performed. The samples are obtained through the conventional solid-state route. The expected microstructure for these compounds, with no significant dependence on the composition, is verified by field-emission scanning electron microscopy. The morphotropic phase boundary (MPB) is detected for x = 0.06-0.07 by means of the Rietveld analysis of X-ray diffraction data. The dielectric spectra show a frequency-independent, completely diffuse phase transition with a composition-dependent diffusivity coefficient. The depolarization temperature is effectively evaluated from pyroelectric measurements, the value being strongly dependent on the composition. A significant contribution of the extrinsic effect to elastic, dielectric and electromechanical properties is revealed for MPB BNT-xBT. The Bi3+ substitution by Ba2+ leads to the formation of A-site vacancies, which give rise to the enhancement of domain wall motion, as occurs in other perovskite-type piezoelectrics. Good functional properties are achieved for x = 0.07 (d(33) = 180 pC/N), which are similar or even better than those obtained by complex synthesis routes. This system exhibits a remarkable stability in the permittivity that has hitherto not been reported. This fact may open the way for BNT-BT compositions to be used in specific applications in which lead-free piezoceramics have previously been employed with little success, e.g. in high power devices. (C) 2016 Elsevier B.V. All rights reserved.

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