Fine particles of bismuth-substituted yttrium iron garnet doped with aluminum, gallium and indium ions are prepared by coprecipitation method. The films with these particles are obtained by dispersing particles on glass substrates with an appropriate epoxy binder. The magnetic and magneto-optical properties of the particles and the films are examined. The lattice sites occupied by aluminum, gallium and indium ions are determined by the relationship between the saturation magnetization and substitution content. The canting of the magnetic moments from the average magnetization axis of the iron ions is deduced in the indium substituted particles. The figure of merit of indium substituted samples remains constant up to the substitution content of 0.5.