Synthesis and Characterization of Ni@CaO Nanocapsules for Multilayer Ceramic Capacitors (MLCCs) Electrodes Prepared In Situ by DC Arc Plasma Method

Ni@CaO nanocapsules for multilayer ceramic capacitors (MLCCs) inner electrodes are synthesized in situ by the DC arc plasma method under nitrogen-rich atmosphere, and their structures, ionic valence states (Ca²⁺, O^2–, Ni^2+/3+), compositions, and other properties are characterized and tested. Based on the principle of oxygen potential, the aerosol growth model is introduced to explain the mechanism of synthesizing Ni@CaO nanoparticles, and it is confirmed that the composition ratio of CaO and Ni can be controlled during co-evaporation. The results show that the prepared pure nickel and all Ni@CaO nanoparticles are pure in physical phase, and the average grain sizes reach the nanometer scale with the smooth “core–shell” spherical structure, and the thickness of CaO shell is approximately 1.5 nm. According to the performance test results, the optimal doping ratio of Ni_(100–x)@CaO_(x) is determined to be 2:8 (CaO:Ni); its average grain size reaches 25 nm, and the oxidation temperature is 454.5 °C, which is 54.7 °C higher than that of the pure nickel samples. Meanwhile, the shrinkage rate of the scale sample decreased from 12.77% of the pure nickel powder for production and 15.31% of the pure nickel sample for S1 to 9.75% at a BaTiO₃ matching temperature of 1200 °C. The variation law of the relationship between nanoparticle size unity and performance is verified. Moreover, its dielectric loss (tan δ) in high-frequency environments is only 0.03, which is greatly reduced, compared to the 0.05 of pure nickel, and can provide larger Q values. Based on this, the characteristics of DC arc plasma method are highlighted, such as simple material and simple process; due to the advantages of high stability and high melting point of CaO, the prepared Ni@CaO powder can be used as the potential substrate for the industrial production of the new generation of MLCCs devices.