Microstructure and electrical performance of Sm2O3-doped BCTSG lead-free ceramics

This work aims to upgrade the comprehensive electrical properties of BaTiO₃-based ceramics (1-x)[(Ba_0.94Ca_0.06)(Ti_0.92Sn_0.08)]-xSm₂O₃-0.06 mol% GeO₂ [abbreviated as (1-x)BCTS-xSm-0.06G]. First, piezoceramics were synthesized via a conventional solid-state method. Next, the phase structures, surface topographies, ferroelectric domains were evaluated using XRD, XRD Rietveld refinements, SEM, OP-PFM, TEM. The results demonstrate that all the ceramics possess an orthorhombic-tetragonal (O-T) phase when at room temperature. Significantly, optimized piezoelectricity is gained at x = 0.03 mol% (piezoelectric constant of d₃₃ = 630 ± 20 pC/N and planar electromechanical coupling factor of k_p = 61%). The ferroelectric domains of ceramics were examined using OP-PFM and TEM, which ulteriorly indicate that the favorable piezoelectricity is attributed to the coexistence of the O-T phase boundary and the subdued energy density of the domain wall. Furthermore, all the ceramics are confirmed to be relaxor ferroelectrics, with the relaxor degree increasing with the increasing content of Sm₂O₃.