Densification and property optimization of BaTiO₃ piezoelectric ceramics fabricated by digital light processing with sintering aids

BaTiO₃ ceramics fabricated by conventional methods have been the primary focus of previous investigations. In contrast, the effects of different sintering aids on DLP-fabricated BaTiO₃ ceramics were systematically investigated over a wide sintering-temperature range. A DLP fabrication route incorporating sintering aids was employed to overcome the limitations of conventional fabrication in producing complex-structured lead-free piezoelectric ceramics with tailored properties. BaTiO₃ ceramics were fabricated using a high-solid-loading photosensitive slurry (85 wt%). Four independent compositions were prepared, each containing a single sintering aid (CuO, SiO₂, TEOS, or Li₂CO₃). The printed samples were subsequently sintered at temperatures ranging from 1375 to 1475 °C to establish clear processing–structure–property relationships. The results show that all sintering aids significantly influence densification behavior, microstructural evolution, and functional properties. Among them, TEOS-containing ceramics exhibit the most balanced overall performance, with optimal properties achieved within 1425–1450 °C. The sample sintered at 1425 °C shows the highest relative density (0.941) and dielectric constant (1904), while the maximum piezoelectric coefficient (d₃₃ = 234 pC/N) is obtained at 1450 °C. CuO addition leads to the highest piezoelectric response (d₃₃ = 258.7 pC/N), but is accompanied by abnormal grain growth and reduced microstructural stability. In contrast, SiO₂- and Li₂CO₃-containing samples exhibit comparatively lower overall performance due to less effective densification and microstructural development. Overall, a systematic comparative framework was established for evaluating the effects of different sintering aids on DLP-fabricated BaTiO₃ ceramics. The combination of sintering-aid engineering and additive manufacturing offers an effective route for optimizing the microstructure and multifunctional performance of lead-free piezoelectric ceramics for energy harvesting and sensing applications.