A colorless and transparent zirconium oxide (Zr0.73Y0.27O1.87) crystal has been synthesized by the Bridgman-Stockbager method. The gem-quality material is produced by adding 20∼25 wt.% Y2O3 (stabilizer) and 0.04 wt.% Nd2O3 (decolorising agent) to the ZrO2 powder. It shows a vitreous luster with a slight oily appearance. Under a polarizing microscope, it shows isotropic nature with no appreciable anisotropism. Mohs hardness value and specific gravity is measured to be 8∼8½ and 5.85, respectively. Under ultraviolet light it shows a faint white glow. The crystal structure of yttria-stabilized zirconia with 0.27 at.% Y has been re-investigated, using single crystal X-ray diffraction, and confirmed to be a cubic symmetry, space group Fmøverline3m (O5h) with a=5.1552(5) A, V=136.99(5) A3, Z=4. The stabilizer atoms randomly occupy the zirconium sites and there are displacements of oxygen atoms with amplitudes of δ/a∼0.033 and 0.11 along 〈110〉 and 〈111〉 from the ideal positions of the fluorite structure, respectively.

• Kim, Won-Sa(Department of Geology, Chungnam National University)
• Yu, Young-Moon(Korea Photonics Technology Institute) | Yu, Young-Moon
• Lee, Jin-Ho(Korea Institute of Geology, Mining and Materials) | Lee, Jin-Ho