INTERDISPERSED THREE-PHASE FERRITE COMPOSITE AND ELECTROGRAPHIC MAGNETIC CARRIER PARTICLES THEREFROM

摘要

Disclosed is an interdispersed three-phase ferrite composite which comprises from about 0.1 mole to about 1.0 mole of a spinel phase having the general formula MFe2O4 where M is at least one element that forms a spinel ferrite and is selected from the group consisting of cobalt, manganese, iron and mixtures thereof, to about 2.5 moles of a magnetoplumbite phase having the general formula PO.6Fe2O3 where P is selected from the group consisting of strontium, barium, calcium, lead and mixtures thereof and, as a third phase, from about 0.02 to about 2.0 percent by weight, based on the combined weight of the spinel phase and the magnetoplumbite phase, of TiO2 or SiO2. Also disclosed are carrier particles formed from magnetized particles of the composite which optionally can be polymerically coated, an electrostatic two-component dry developer composition comprising charged toner particles mixed with oppositely charged carrier particles formed from magnetized, and optionally polymerically coated, particles of the composite, and a method of developing an electrostatic image by contacting the image with a two-component dry developer composition described above.