Structural, ferroelectric, optical properties of A-site-modified Bi0.5(Na0.78K0.22)0.5Ti0.97Zr0.03O3 lead-free piezoceramics

• The Bi0.5(Na(0.82−x)K0.18Lix)0.5(Ti0.97Zr0.03)O3 (x=0.00÷0.05) ceramics were prepared by a conventional solid state reaction route.
• The both rhombohedral and tetragonal structures were distorted by Li dopant.
• The Smax/Emax values increased from 600 to 643 pm/V.
• The Eg and Pm decreased from 2.88 to 2.68 eV and from 46.2 to 26.1 μC/cm2, respectively.
• The role of A-site dopants in comparison with B-site modification in Bi0.5(Na,K)0.5TiO3-based ceramics was presented.

We reported the role of A-site modification on the structural, ferroelectric, optical and electrical field-induced strain properties of Bi0.5(Na0.78K0.22)0.5Ti0.97Zr0.03O3 lead-free piezoceramics. The Li+ ions with concentration from 0 to 5 mol% were used to substitute at A-site. There was no phase transition when Li+ ions was added up to 5 mol%. The electric field-induced strain (Smax/Emax) values increased from 600 to 643 pm/V for 2 mol% Li+-added which results from distortion both rhombohedral and tetragonal phase structures. The band gap reduced from 2.88 to 2.68 eV and the saturation polarization decreased from 46.2 to 26.1 μC/cm2 when Li+ ions concentration increased from 0 to 5 mol% respectively. We expect that this work could be helpful for further understanding the role of A-site dopants in comparison with B-site modification in lead-free Bi0.5(Na,K)0.5TiO3-based ceramics.

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