Special attention has been given to partially stabilized ZrO2 (PSZ), tetragonal ZrO2 polycrystal (TZP), and ZrO2-toughened Al2O3 (ZTA) to improve the fracture toughness (KIC) and bending strength (σb) of ceramics. In a recent study, it was shown that in the system ZrO2-Al2O3, ZrO2 solid solutions (ss) are formed metastably up to ≈40 mol% Al2O3 from amorphous materials prepared by the alkoxy-method. Isostatically hot-pressed ZrO2(ss) ceramics exhibit very high KIC (23 MPa⋅m1/2) and plastic deformation at room temperature, although their σb is weak (≤700 MPa). The texture consists of a homogeneous microstructure with a grain size of ≈50nm. To improve ab, two kinds of ceramics have been fabricated by the addition of a small amount of Y2O3: (1) perfect ZrO2(ss) ceramics and (2) composite ceramics of ZrO2(ss) and a-Al2O3. Composites with a homogeneous dispersed cc-Al2O3 result in a remarkable increase of σb (1445 MPa). The ratio of ZrO2(ss) and α-Al2O3 can be controlled by the amount of Y2O3 addition and sintering temperature. A new method for preparing solid solutions from chlorides using hydrazine monohydrate has been developed in some systems. This paper describes the mechanical properties of PSZ, TZP and ZTA ceramics fabricated using ZrO2(ss) powders prepared by some sol-gel techniques.