The Effect of Different A-Site Divalent Elements on the Properties of Bi4Ti3O12-Based Piezoelectric Ceramics with Symbiotic Structure

Bismuth layer-structured ferroelectrics (BLSFs) are core candidates for high-temperature piezoelectric applications owing to their excellent thermal stability and fatigue resistance, yet traditional Bi4Ti3O12 (BiT)-based ceramics suffer from limited piezoelectric performance. To address this, MBi4Ti4O15-Bi4Ti3O12 (M=Ba, Sr, Ca) symbiotic structure bismuth-layered piezoelectric ceramics were fabricated via the conventional solid-state reaction method. Their crystal structure, microstructure, and electrical properties were systematically characterized using a X-ray diffractometer, scanning electron microscope, high-temperature dielectric spectrometer, and quasi-static d33 meter to explore the effects of different A-site divalent elements. Results show that all samples form a pure-phase symbiotic structure with the P21am space group, without secondary phases. The lattice constant decreases with increasing A-site ionic radius, while symbiosis-induced lattice mismatch and long-range disorder refine grains, reduce aspect ratio, lower conductivity, enhance spontaneous polarization, and improve piezoelectric properties. The ceramics exhibit d33 of 10 to 15 pC/N and TC of 502 to 685 °C, with SrBi4Ti4O15-Bi4Ti3O12 showing optimal comprehensive performance (d33 ≈ 15 pC/N, TC = 593 °C, tanδ = 0.6% at 1 kHz/475–575 °C, and a low AC conductivity of 5.3 × 10−5~4.8 × 10−4 S/m). This study improves bismuth-layered ceramics’ performance via A-site regulation and symbiotic structure design, offering theoretical and technical support for high-performance lead-free high-temperature piezoelectric ceramics.