Tunable d33/d33* for MPB (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 lead-free piezoceramic by crystallographic texturing approach

Abstract

The morphotropic phase boundary (MPB) Ba0.85Ca0.15Zr0.10Ti0.90O3 composition is successfully transferred into <001>-textured ceramic having Lotgering factor f-74 % (abbreviated as BCZT-T74) using high aspect ratio BaTiO3-template particles via templated grain growth (TGG) method. The microstructural aspects reveal the distinctive grain growth formation for non-textured (BCZT-NT) and textured (BCZT-T74) ceramics; confirming the proper grain growth formation for textured ceramics. The polarization behavior was tested at 1 Hz, 5 Hz, and 10 Hz electric field frequencies by applying a voltage bias of 1000 V; the BCZT-NT ceramics show more variation in remnant polarization (Pr) as well as maximum polarization (Pmax) peak position while BCZT-T74 ceramics exhibit nearly steady values. The frequency-dependent variation in Pr (i.e. ΔPr) for non-textured and textured BCZT ceramics is ±11.08 % and ±3.25 % respectively in the frequency range 1Hz–10Hz at an applied voltage bias of 1000 V. The bipolar strain-electric field (S-E) butterfly loop evidences the typical piezoelectric nature; for both non-textured and textured BCZT ceramics having the effective piezoelectric strain coefficient d33* of 576 pm/V and 657 pm/V respectively. The BCZT-NT and BCZT-T74 ceramics revealed the average positive strain % values of 0.063 % and 0.1123 % and negative strain % values of 0.003985 % and 0.02281 % respectively at the applied voltage 1000 V functioning at 1Hz. The enhancement in negative strain% for BCZT-T74 ceramics is > 5.70 times higher than BCZT-NT ceramics. The variation in positive strain (i.e. ΔS+ve) and variation in negative strain (i.e. ΔS-ve) for non-textured ceramics is ±11.74 % and ±67.34 %, however, for textured ceramics is only ±3.33 % and ±5.00 % respectively. The BCZT-NT and BCZT-T74 ceramics exhibit the piezoelectric charge coefficient (d33) of 370 pC/N and 520 pC/N (1.4 times that of BCZT-NT ceramics) respectively. The electrostrictive coefficient (Q33) of BCZT-T74 ceramics is 0.039 m4/C2, which is > 2 times higher than BCZT-NT ceramics as well as commercially used toxic PZT-5H ceramics. Therefore, less variation in a strain, as well as polarization nature with varying frequencies and enhancement in piezo properties, suggests the present textured MPB BCZT-T74 ceramics is a promising candidate for piezoelectric devices functioning at the wide range of applied electric field frequencies.