| 초록 |
Zirconia ceramics are currently being studied as dental materials, and efforts are being made to improve transparency and strength. Zirconia ceramics exist in monoclinic phase at room temperature, and when 3mol% Y2O3 is added, zirconia ceramics are present in quasi-stable phase. These zirconia ceramics are known to increase in volume by about 3-5% when the external force is applied, and the breakthrough strength is increased due to the transformation of tetragonal phase to monoclinic phase. Due to its excellent fracture strength, it is used as a very thin dental implant material. On the other hand, Zr of zirconia has a valence of +4 and an effective ion radius of 72 pm. Addition of 3mol% of Y3+ to this gives the effect of delaying the transformation of the monoclinic phase from tetragonal phase, which occurs when the temperature is lowered from room temperature to high temperature, and maintaining the tetragonal phase as a metastable phase at room temperature. At this time, the effective ion radius of Y3+ is 90 pm, which is much larger than that of Zr4+. And 3mol% of Y3+ occupies a part of the tetragonal normal unit, which is believed to contribute stoichiometrically to the overall crystal structure. In this study, we have investigated the effect of phase transition phenomena and translucency of zirconia when Y3+ was added to an element with different effective ionic radius. The elements added were Ga3+, Ru3+, In3+, Er3+ and the effective ion radii of these elements were 62, 68, 80, and 88pm, respectively. In other words, the phenomenon of phase transformation when XRD, SEM, Mesuring Sinter density. were investigated when the ion radius is smaller or larger than the effective ion radius of Zr4+. |
