Gas bubbles appear in some metal oxides grown by directional solidification in air when high growth rates are used. The incorporation of bubbles in Al2O3-YAG (AY) and Al2O3-YAG-ZrO2 (AYZ) eutectic crystals grown using the laser floating zone method was investigated. The effect of different growth experimental parameters was considered. Growth rate, rod diameter and growth atmosphere were found to be determinant in order to reduce the gas inclusions. The optimization of the growth parameters allowed to grow AY and AYZ eutectic crystals free of bubbles at very high growth rates at which interphase spacings smaller than 300 nm were obtained. (c) 2007 Elsevier B.V. All rights reserved.