Influence of MnO2 addition on the dielectric properties of 0.95MgTiO3-0.05CaTiO3 ceramics sintered in a reducing atmosphere

The increasing cost of palladium has demonstrated the significant value of using inexpensive base metals as inner electrodes for RF/microwave multilayer ceramic capacitors . However, solving the co-sintering problem of dielectric ceramics with base metals such as copper is highly challenging, as sintering in a reducing atmosphere is required to prevent the oxidation of the base metals. In this work, the feasibility of sintering nonreducible MnO 2 -doped 0.95MgTiO 3 -0.05CaTiO 3 (95MCT) ceramics in a reducing atmosphere (H 2 -N 2 , p O 2 = 1 × 10 − 10 ∼ 1 × 10 − 11 MPa) at 1000 °C was investigated. The effects of the MnO 2 additive (1.6–2.4 mol%) on the phase structures, dielectric properties , and thermal stability were studied. Thermally stimulated depolarization current (TSDC) analysis and X-ray photoelectron spectroscopy (XPS) were conducted to characterize the oxygen vacancies and Mn ion valence state in MnO 2 -doped ceramics, indicating that Mn plays an important role in the dielectric properties, especially the extrinsic dielectric loss. With the optimized addition of 2.0 mol% MnO 2 , due to the decrease in oxygen vacancy concentration, the samples with ε r = 20.22 exhibited the attractive properties of a high insulation resistivity of IR = 3.65 × 10 14 Ω ∙ cm and a low dielectric loss of tan δ = 0.036 % , meeting the C0G specifications. The results show that the 2.0 mol% MnO 2 -doped 0.95MgTiO 3 -0.05CaTiO 3 ceramic is an outstanding nonreducible dielectric material for base-metal electrode RF/microwave multilayer ceramic capacitor applications with low cost, excellent dielectric properties, and high reliability.