Microstructure and suppressed thermal depolarisation behaviours of lead-free Na_0.5Bi_0.5TiO₃:ZnO ferroelectric composite ceramics

ABSTRACT

A 0–3 type 0.8Na_0.5Bi_0.5TiO₃(BNT):0.2ZnO lead-free ferroelectric composite ceramic structure was prepared by a solid-state oxide route. The X-ray diffraction analysis and scanning electron microscopy observation indicate that ZnO grains were scattered in the matrix consisting of BNT grains to form a (0–3) type composite structure, and a third phase Zn₂TiO₄ was formed due to the reaction ability of nano-sized ZnO with NBT compositions. The temperature-dependent electrical responses show that the dielectric anomaly at around 200°C inherited from NBT itself was suppressed as ZnO is composited, and the P_r of the specimen sintered at 1000°C keeps almost unchanged as the poling temperature is 175°C, while its retained piezoelectric strain d₃₃ value maintains 77% of the initial as exposed to 125°C annealing. These results suggest that the thermal depolarisation of BNT is suppressed due to the introduction of ZnO, even though the third phase Zn₂TiO₄ exists.

KEYWORDS:

• Sodium bismuth titanate
• thermal depolarisation
• ferroelectrics
• composite ceramics

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Mupeng Zheng http://orcid.org/0000-0001-7547-5025

Additional information

Funding

The work is partially supported by the National Natural Science Foundation of China (Nos. 51602012 and 51677001), the Natural Science Foundation of Beijing Municipality (No. 4164078), and Research Fund for the Doctoral Program of Higher Education of China (No. 20131103110031). Jing-Hua Talents Project of Beijing University of Technology (No. 2015-JH-L04).