Isothermal tetragonal to monoclinic transformation substituted for yttrium ions, during which a certain where Vo is the oxygen vacancy. The amount of re ected to be oxygen vacancies can be characterized by following produced to hold the ionic neutralization. The fol- formula: 4 wing reaction can be used to describe above process: 8 ZrO2+Y203-2Yzr vo+ 300 100+M (d) 0.3 Fig9. Precipitation of t-phase within a c-phase grain of Zro2(3 mol%Y203)specimens:(a)and(b) bright field images showing ne co-existence of c, t and m-phases;(c)diffraction pattern of the c-phase; (d)dark field image taken by using a(112)forbidden 0.3pm 0.3m Fig. 10. TEM photographs showing the in-situ formation of parallel lathed m-phase, induced by the irradiation of an electron beam in a ZrO, (2 mol%Y2O3) ceramicIsotherm !a1 tetragonal to monoclinic transformation substitu ted for yttrium ions, during which a certain number of oxygen vacancies are expected to be produce :d to hold the ionic neutralization. The fol￾lowing reaction can be used to describe above process: 8 Zr02 + Y2O3 + 2Yz, + Vo + 300 41 where V0 is the oxygen vacancy. The amount of oxygen vacancies can be characterized by following formula: l4 v= 4M lOO+h4 I, 0.3 pm I Fig. 9. Precipitation of t-phase within a c-phase grain of Zr02(3 mol% YzOs) specimens: (a) and (b) bright field images showing the co-existence of c, t and m-phases; (c) diffraction pattern of the c-phase; (d) dark field image taken by using a (112) forbidden spot. Fig. 10. TEM photographs showing the in-situ formation of parallel lathed m-phase, induced by the irradiation of an electron beam in a ZrOz(2 mol% Y*Os) ceramic