Tailoring the ultrafine Ni@NiO core-shell structure for advanced film electrode applications

Nickel (Ni) ultrafine particles are widely used for the fabrication of inner film electrodes of multilayer ceramic capacitors (MLCCs). In this study, we report an approach to prepare Ni@NiO core-shell ultrafine particles with a size of about 120 nm. Instead of using commonly commercial Ni particles as Ni cores, we prepare Ni ultrafine particles via an aqueous solution reduction, and then conduct a crystallization optimization, followed by a controlled oxidation. NiO shells with a tunable shell thickness ranging from 4 to 7 nm are formed on Ni cores. The Ni@NiO core-shell ultrafine particles exhibit significantly improved oxidation resistance and thermal shrinkage resistance. The corresponding sintered film shows enhanced film integrity and continuity with a low resistivity of 10.6 μΩ cm. The prepared Ni@NiO core-shell ultrafine particles may find potential applications in the field of high-capacity MLCC with thinner Ni electrode layers.