In-situ preparation of Ni@ZrO2 nanocapsules powder by DC arc plasma for internal electrode of MLCC

Zirconium oxide-coated Ni nanocapsules (Ni@ZrO2 NCs) were in-situ fabricated by DC arc plasma in a nitrogen atmosphere. The co-evaporation of a target mixture consisting of coarse ZrO2 and Ni powders resulted in the formation of Ni@ZrO2 core-shell nanocomposites (NCs). The high energy states of excited ions (Ni3+, Zr4+, O2−, N2+, etc.) within the arc plasma region were recorded in real time by online optical emission spectroscopy (OES), which becomes visible evidences of the energy conditions for the fabrication of Ni@ZrO2 NCs. These nanocapsules underwent preferential formation of zirconium oxide species based on the oxygen potential rule, followed by the nucleation and subsequent growth processes. The Ni@ZrO2 NCs exhibited improved oxidation resistance, with an onset temperature for sintering approximately 40 °C higher than that of pristine Ni nanoparticles (NPs). Additionally, these NCs displayed an appropriate shrinkage rate, with a volume change of about 7.1% at 1200 °C. The symbiotic relationship between the ZrO2 shell and the Ni core within each nanoparticle suggests enhanced interfacial stability, rendering these NCs a promising material for the advancement of multi-layer ceramic capacitors (MLCCs).