A new bismuth-substituted mixed rare-earth iron garnet bulk single crystal of composition (YYbBi)(3)Fe5O12 (YYbBiIG) has been grown by the improved flux method, whose temperature derivative 0 of Faraday rotation angle at 45degrees has been modified by substituting Y3+ and Yb3+ ions in garnet crystals. The Faraday rotation and the optical absorption coefficient of Y1.53Yb0.92Bi0.55Fe5O12 at 1550 nm were found to be -634degrees cm(-1) and 2.56 cm(-1), respectively. The Faraday rotation temperature derivative beta was 0.01degrees (degreesC)(-1) at 1550 nm wavelength, the saturation magnetization 4pi M-s has been estimated to be about 1200 G. The larger Faraday rotation, low optical loss, low saturation magnetization and nearly zero temperature derivative 8 of Faraday rotation of YYbBiIG crystal promise its use in high-performance magnet-optical applications. (C) 2002 Elsevier Science B.V. All rights reserved.