| 摘要 |
An interdispersed two-phase ferrite composite which comprises, as a ferromagnetic phase, a magnetically hard ferrite material having a hexagonal crystalline structure of the general formula RxP(1-x)Fe12O19 where R is selected from rare earth elements, P is selected from the group consisting of strontium, barium, lead, calcium and mixtures thereof and x has a value of from 0.1 to 0.4 exhibiting a coercivity of at least 300 Oersteds when magnetically saturated and an induced magnetic moment of at least 20 EMU/g when in an applied magnetic field of 1000 Oersteds and, as a ferroelectric phase, a ferroelectric material comprised of at least one of the double oxides of titanium, zirconium, tin, hafnium or germanium and either an alkaline earth or lead or cadmium, in which the mole ratio of the ferromagnetic phase to the ferroelectric phase is from 1:1 to 1:4. 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 electrically insulative charged toner particles mixed with oppositely charged carrier particles formed from magnetized, and optionally polymerically coated, particles of the composite suitable for extremely high speed copying applications without the loss of copy image quality, and a method of developing an electrostatic image by contacting the image with a two-component dry developer composition previously described. |
