Growth of MgAl₂O₄/MgO eutectic crystals by the micro-pulling-down method and its characterization

MgAl₂O₄/MgO eutectic fibers and rods have been grown successfully by the micro-pulling-down method, and the microstructures and optical characterizations of grown crystals were performed. MgAl₂O₄/MgO eutectic fibers of 0.3-1 mm in diameter and about 500 mm in length, and the rods having 5 mm in diameter with approximately 60 mm in length have been grown with the 6-120 mm/h of growth speed. The eutectic fibers showed homogeneous microstructure in which MgO fiber/whisker aligned to the growth direction in the MgAl₂O₄ (spinel) matrix. The grown crystals looked semitransparence under naked eyes. Optical and orientational characterizations were performed. The second phase of MgO was easily removed by selective etching with hydrochloric acid, and then porous single crystalline bodies were obtained.