Enhanced breakdown strength and dielectric loss of Ca_1−3x/2Eu_xCu₃Ti₄O₁₂ ceramics prepared by polymer pyrolysis

The CaCu₃Ti₄O₁₂ (CCTO) ceramic is characterized by high dielectric constant, but its elevated dielectric loss (tanδ) and low breakdown field strength (E_b) limit its practical applications in small electronic devices. Therefore, Ca_1−3x/2Eu_xCu₃Ti₄O₁₂ (x = 0, 0.2, 0.4, and 0.6) samples were prepared through a combined strategy of substituting with rare earth element and polymer pyrolysis method to improve the tanδ and E_b. XRD analysis revealed that main phase of CCTO was formed in all samples, and Eu³⁺ ions were incorporated into the lattice. These results suggest that the low concentrations of Eu facilitate grain growth. However, as the concentration increases, it begins to have an inhibitory effect on grain growth, consequently resulting in an elevated grain boundary density. Moreover, the results demonstrated that the addition of Eu enhanced the E_b, reduced the tanδ, and improved the temperature stability of the CCTO ceramics. Interestingly, impedance analysis reveals a notable enhancement in grain boundary resistance. Notably, the Ca_0.4Eu_0.4Cu₃Ti₄O₁₂ sample demonstrated an exceptionally high grain boundary resistance of 6.62 × 10¹⁰ Ω cm, surpassing that of pure CCTO by over 100-fold. Ca_1−3x/2Eu_xCu₃Ti₄O₁₂ ceramics possess low loss and high breakdown performance, making them promising materials in capacitors.