Effect of Sn addition on the low temperature shrinkage of Ni nanoparticles

Abstract

In this study, in-situ formation of intermetallic compound (IMC) was proposed to reduce the sintering shrinkage mismatch between Ni electrode and dielectric material for multilayer ceramic capacitors (MLCCs). Tin (Sn) was selected as an alloying element and introduced in the form of SnCl2 into Ni nanopowder. The Sn precursor was decomposed at ∼450 °C and a cubic Ni3Sn intermetallic phase was formed at 500 °C, which was gradually transformed to a hexagonal Ni3Sn phase at 700 °C and thereafter thermally decomposed above 800 °C forming the Ni–Sn solid solution. The Sn addition shifted the shrinkage onset temperature of Ni electrode to a higher temperature by 300–400 °C and effectively retarded the low temperature densification through in-situ formation of Ni3Sn intermetallics by inhibiting the inter-diffusion between Ni nanoparticles. Furthermore, the sintered Sn added Ni (Ni–3Sn) electrode exhibited an electrical conductivity comparable to that of pure Ni electrode, demonstrating its suitability as an alternative electrode for MLCCs.