Nanocrystalline Bi-substituted yttrium iron garnet films have been prepared by coprecipitation titration, once-through coating of hydroxide slurry, and pyrolysis. The resulting films with grain sizes of 10-20 nm are fabricated at a pH value of 12 and heat treated of 700 degrees C for 1 h. At the incident light wavelength of 633 nm, the maximum special Faraday rotation of 3.6 x 10(4)degrees/cm and Faraday magneto-optical figure of merit of 6.7 degrees/dB were obtained. The influence of pH value and heat treatment on film grain size, crystallinity, and magneto-optical properties is demonstrated. (c) 2008 Elsevier B.V. All rights reserved.