Mapping the transition from carbon-onions filled with Fe₃C to carbon-foam completely filled with α-Fe: Unlocking mass-production of ferromagnetic carbon foam

A key challenge in the fabrication of carbon materials filled with ferromagnetic crystals is the achievement of a highly-efficient production with high purity. This is fundamental for the translation of these materials into technological applications at low cost. Here we present an innovative approach which allows the highly-efficient production of large quantities of carbon foam completely filled with ferromagnetic α-Fe with very high-magnetization-characteristics. In this novel approach the foam-nucleation is triggered by not previously reported distortion and decomposition effects of the graphitic layers comprised in the shells of Fe₃C filled carbon-onions. Such unusual effects are found to induce a sintering-like catalyst-fusion process during annealing at high temperatures.