Preparation of Spherical Fine Particles of yttrium/Iron Composite by Precipitation from Homogeneous Solution Containing Urea

摘要

Fine composite particles containing yttrium and ironwere prepared from homogeneous solution using urea as aprecipitant generator. The ratio of yttrium to iron in the precipitatecould be controlled by adjusting the concentration of the startingmaterials in the initial solution. These composite particles wereconsidered to be amorphous. Shapes and morphology of theprecipitated particles were influenced by the difference of thereaction conditions. Particles obtained from the solutioncontaining 1.88mmol dm-3 FeCl3·6H2O, 3.13mmol dm-3YCl3·6H2O and 500mmol dm-3 urea at 97°Cwere almost sphericaland mono-dispersed, Particles precipitated on the condition asmentioned above converted from amorphous into monophasicgarnet (Y3Fe5O12) by calcining at 1,200°C for 5 hours. Aftercalcination, particle changed its color from brown to mediumolive and indicated marked magnetic character.