Patent ID: 8906983

Claim:
An iron-silicon oxide particle, comprising: a core and an outer shell, wherein the core comprises maghemite, magnetite, and haematite, as iron oxide modifications, the outer shell consists essentially or exclusively of amorphous silicon dioxide, the particle satisfies: B 0.20 nm /B 0.25 nm is ≦0.2, B 0.20 nm is brightness of a Debye-Scherrer diffraction ring determined by electron diffraction at a lattice plane spacing of 0.20+/−0.02 nm, comprising maghemite and magnetite, B 0.25 nm is brightness of a Debye-Scherrer diffraction ring determined by electron diffraction at a lattice plane spacing of 0.25+/−0.02 nm, comprising maghemite, magnetite and haematite, and a crystallite diameter of the haematite determined by X-ray diffraction is greater than 120 nm.