J. Mater. Sci. Technol. ›› 2022, Vol. 117: 207-214.DOI: 10.1016/j.jmst.2022.02.002

• Research Article • Previous Articles     Next Articles

Ultrahigh strain in textured BCZT-based lead-free ceramics with CuO sintering agent

Yingchun Liua, Hongjun Zhanga,*(), Wenming Shia, Qian Wanga, Guicheng jianga, Bin Yanga, Wenwu Caoa,b, Jiubin Tanc   

  1. aFunctional Materials and Acoustooptic Instruments Institute, School of Instrumentation Science and Engineering, Harbin Institute of Technology, Harbin 150080, China
    bDepartment of Mathematics and Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
    cUltra-precision Optical & Electronic Instrument Engineering Center, Harbin Institute of Technology, Harbin 150 0 01, China
  • Received:2022-01-04 Revised:2022-02-10 Accepted:2022-02-11 Published:2022-02-19 Online:2022-08-01
  • Contact: Hongjun Zhang
  • About author:∗E-mail address: zhanghj@hit.edu.cn (H. Zhang).

Abstract:

Textured BaTiO3 (BT)-based lead-free ceramics have gained significant attention due to their high piezoelectric coefficient (d) and very large field induced strain (S). However, costly nano-size raw materials, excessively high sintering temperature and low Curie temperature (Tc) hinder their device applications. In this work, highly [001]c-oriented (Ba0.95Ca0.05)(Zr0.04Ti0.96)O3 ceramics with x mol% CuO (x = 0.25, 0.5, 1.0, 2.5) denoted as BCZT-x were synthesized by templated grain growth using micro-sized raw powders. The introduction of CuO sintering agent lowered the sintering temperature by 125 °C to 1450 °C, and the BCZT-1.0 achieved a high texture degree of ∼99%. In addition, the CuO-based liquid phases eliminated boundaries between BT templates and BCZT matrix powders. Such liquid-phase sintering reduced sintering stresses, decreased the average grain size of BCZT-1.0 from 16 μm down to 13 μm, and increased the dielectric dispersion coefficient γ to 1.63. The almost smoothed out TO-T anomaly in the temperature dependence of dielectric permittivity and comparably high Tc (> 102 °C) lead to better temperature stability. The narrower grain orientation distribution with full width at half maximum (FWHM) of ∼5.9° and smaller domains with the size of 0.1-0.5 μm in width and 3-8 μm in length were obtained, a high field induced maximum strain Smax of 0.38% and low Hs of 5.2% have been achieved in BCZT-1.0 textured ceramics together with a high and homogeneous piezoelectric stress coefficient d33 ∼780 pC/N and very large d33* ∼2950 pm/V.

Key words: Lead-free, BCZT, Textured ceramics, Piezoelectric, Strain hysteresis