Applied magnetic field rejects the coating of ferromagnetic carbon from the surface of ferromagnetic cobalt: RAPET of CoZr₂(acac) ₂(OⁱPr)₈

We present the results of the RAPET (reaction under autogenic pressure at elevated temperatures) dissociation of CoZr₂(acac)₂(O ⁱPr)₈ at 700°C in a closed Swagelok cell under an applied magnetic field of 10 T. It produces a mixture of carbon-coated and noncoated metastable ZrO₂ nanoparticles, bare metallic Co nanoparticles, and bare carbon. The same reaction in the absence of a magnetic field produces spherical Co and ZrO₂ particles in sizes ranging from 11 to 16 nm and exhibiting, at room temperature, metastable phases: fee for cobalt and a tetragonal phase for zirconia. The metastable phases of Co and ZrO₂ are manifested because of a carbon shell of ∼4 nm thickness anchored to their surfaces. The effect of an applied magnetic field to synthesize morphologically different, but structurally the same, products is the key topic of the present paper.