Selective Synthesis of Peapodlike Ni/Ni3S2Nanochains and Nickel Sulfide Hollow Chains and Their Magnetic Properties

Peapodlike Ni/Ni3S2chains of about 30 nm in outer diameter, with Ni cores of 10–15 nm, can be synthesized by a sacrificial template route. The Ni3S2shell exhibits paramagnetic properties with a mass susceptibility of χ≈ 5 × 10−5emu (gOe)−1, while the ferromagnetic Ni cores show a superparamagnetic behavior with a blocking temperature of TB≈ 130 K. The shape anisotropy of the chainlike structure is determined as 5.0 × 104J·m−3, which is larger than the bulk magnetocrystalline anisotropy by one order of magnitude. The demagnetization factor is determined as ΔN= 0.29. The sample provides an ideal structure for studying the magnetization reversal property by the chain‐of‐sphere model. The observations on the formation of the peapod structure verify a growth mechanism of the nanoscale Kirkendall effect. Based on the preparation of peapod chains, a series of nickel sulfide hollow chains with average diameters of 25, 50, and 100 nm are fabricated. In addition, the phase transition for hollow chains from Ni3S2to NiS is studied.