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Yttria-stabilized zirconia (YSZ) is a ceramic in which the crystal structure of zirconium dioxide is made stable at room temperature by an addition of yttrium oxide. These oxides are commonly called "zirconia" (ZrO2) and "yttria" (Y2O3), hence the name. == Stabilization == Pure zirconium dioxide undergoes a phase transformation from monoclinic (stable at the room temperature) to tetragonal (at about 1173 °C) and then to cubic (at about 2370 °C), according to the scheme: monoclinic (1173 °C) tetragonal (2370 °C) cubic (2690 °C) melt Obtaining stable sintered zirconia ceramic products is difficult because of the large volume change accompanying the transition from tetragonal to monoclinic (about 9%). Stabilization of the cubic polymorph of zirconia over wider range of temperatures is accomplished by substitution of some of the Zr4+ ions (ionic radius of 0.82 Å, too small for ideal lattice of fluorite characteristic for the tetragonal zirconia) in the crystal lattice with slightly larger ions, e.g., those of Y3+ (ionic radius of 0.96 Å). The resulting doped zirconia materials are termed ''stabilized zirconias''.〔H. Yanagida, K. Koumoto, M. Miyayama, "The Chemistry of Ceramics", John Wiley & Sons, 1996. ISBN 0 471 95627 9.〕 Materials related to YSZ include calcia-, magnesia-, ceria- or alumina-stabilized zirconias, or partially stabilized zirconias (PSZ). Hafnia stabilized Zirconia is also known. Some of the abbreviations used in conjunction with stabilized zirconias are as follow: * Partly stabilized zirconia ZrO2: * * PSZ - ''Partially Stabilized Zirconia'' * * TZP -''Tetragonal Zirconia Polycrystal'' * * 4YSZ: with 4 mol-% Y2O3 partially Stabilized ZrO2, ''Yttria Stabilized Zirconia'' * Fully stabilized zirconias ZrO2: * * FSZ - ''Fully Stabilized Zirconia'' * * CSZ - ''Cubic Stabilized Zirconia'' * * 8YSZ - with 8 mol-% Y2O3 Fully Stabilized ZrO2 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Yttria-stabilized zirconia」の詳細全文を読む スポンサード リンク
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