In the context of the rapid development of the electronics industry, ceramic capacitors with a wide temperature range and high stability are highly desirable. In this paper, we propose a synergistic optimization strategy to enhance the temperature stability of CaCO3-doped BaTiO3–0.01MgO–0.01Nb2O5–0.005Bi2O3 (abbreviated to BTMNB-xCaCO3) ceramics by flash sintering at a furnace temperature of about 1050 °C via combining an electric field of 150 V/mm and a current density of 20 mA/mm2 in 60 s. The XRD and Raman results indicate that Ca2+ is chosen as an acceptor ion effectively replacing Ti4+ within BTMNB-xCaCO3 when x is over 0.03. It is further confirmed by XPS analysis, the content of Ti3+ first increases and then decreases with the increase of x, and achieve a maximum when x = 0.03. Meanwhile, Mg2+and Bi3+, Nb5+are acceptor ∙nd donor ions, specific defects such as \([{\text{Bi}}_{{{\text{Ba}}}}^{ \cdot } - {\text{Ca}}_{{{\text{Ti}}}}^{\prime \prime } - {\text{Bi}}_{{{\text{Ba}}}}^{ \cdot } ]^{ \times }\) , \([{\text{Nb}}_{{{\text{Ti}}}}^{ \cdot } - {\text{Ca}}_{{{\text{Ti}}}}^{\prime \prime} - {\text{Nb}}_{{{\text{Ti}}}}^{ \cdot } ]^{ \times }\) , \([{\text{Mg}}_{{{\text{Ti}}}}^{\prime \prime} - {\text{V}}_{{\text{O}}}^{ \cdot \cdot } ]^{ \times }\) and \([{\text{Ca}}_{{{\text{Ti}}}}^{\prime \prime} - {\text{V}}_{{\text{O}}}^{ \cdot \cdot } ]^{ \times }\) can be formed, and the concentration and distribution of electric charge carriers can be effectively modulated, optimizing the polarization mechanism, enhancing dielectric constant and reducing losses. The Curie temperature shifts to a lower temperature due to Ca2+ substitutes the B-site resulting in excellent temperature stability. The BTMNB-0.03CaCO3 ceramics exhibit a room-temperature dielectric constant of 1913, a dielectric loss of 0.025, and good temperature stability (Δεr/ε25 ≤ ± 15%, over the temperature range from − 88 to 170 °C). This work presents a sustainable strategy for optimizing the dielectric performance of lead-free ceramics over a wide temperature range through the strategic manipulation of defects. Furthermore, it confirms that flash sintering is a practical and cost-effective approach for the low-cost and sustainable development of the ceramic manufacturing industry.
