Premium
Microstructure and Electrical Properties of Nonstoichiometric 0.94(Na 0.5 Bi 0.5+ x )TiO 3 –0.06BaTiO 3 Lead‐Free Ceramics
Author(s) -
Qiao XiaoShuang,
Chen XiaoMing,
Lian HanLi,
Chen WeiTing,
Zhou JianPing,
Liu Peng
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13941
Subject(s) - dielectric , materials science , curie temperature , analytical chemistry (journal) , microstructure , dielectric loss , ferroelectricity , mineralogy , lattice constant , condensed matter physics , diffraction , ferromagnetism , chemistry , composite material , optics , physics , chromatography , optoelectronics
0.94(Na 0.5 Bi 0.5+ x )TiO 3 –0.06BaTiO 3 ( x = −0.04, 0, 0.02; named NB 0.46 T‐6 BT , NB 0.50 T‐6 BT , NB 0.52 T‐6 BT , respectively) lead‐free piezoelectric ceramics were prepared via the solid‐state reaction method. Effects of Bi 3+ nonstoichiometry on microstructure, dielectric, ferroelectric, and piezoelectric properties were studied. All ceramics show typical X‐ray diffraction peaks of ABO 3 perovskite structure. The lattice parameters increase with the increase in the Bi 3+ content. The electron probe microanalysis demonstrates that the excess Bi 2 O 3 in the starting composition can compensate the Bi 2 O 3 loss induced during sample processing. The size and shape of grains are closely related to the Bi 3+ content. For the unpoled NB 0.50 T‐6 BT and NB 0.52 T‐6 BT , there are two dielectric anomalies in the dielectric constant–temperature curves. The unpoled NB 0.46 T‐6 BT shows one dielectric anomaly accompanied by high dielectric constant and dielectric loss at low frequencies. After poling, a new dielectric anomaly appears around depolarization temperature ( T d ) for all ceramics and the T d values increase with the Bi 3+ amount decreasing from excess to deficiency. The diffuse phase transition character was studied via the Curie–Weiss law and modified Curie–Weiss law. The activation energy values obtained via the impedance analysis are 0.69, 1.05, and 1.16 eV for NB 0.46 T‐6 BT , NB 0.50 T‐6 BT and NB 0.52 T‐6 BT , respectively, implying the change in oxygen vacancy concentration in the ceramics. The piezoelectric constant, polarization, and coercive field of the ceramics change with the variation in the Bi 3+ content. The Rayleigh analysis suggests that the change in electrical properties of the ceramics with the variation in the Bi 3+ amount is related to the effect of oxygen vacancies.