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.