Metastable tetragonal ZrO2, phase has been observed in ZrO2-SiO2 binary oxides prepared by the sol-gel method, There are many studies concerning the causes of ZrO2, tetragonal stabilization in binary oxides such as Y3O2-ZrO2, MgO-ZrO2, or CaO-ZrO2,. In these binary oxides, oxygen vacancies cause changes or defects in the ZrO2, lattice parameters, which are responsible for tetragonal stabilization. Since oxygen vacancies are not expected in ZrO2-SiO2 binary oxides, tetragonal stabilization should just be due to the difficulty of zirconia particles growing in the silica matrix, Furthermore, changes in the tetragonal ZrO2 crystalline lattice parameters of these binary oxides have recently been reported in a previous paper, The changes of the zirconia crystalline lattice parameters must result from the chemical interactions at the silica-zirconia interface (e.g,, formation of Si-O-Zr bonds or Si-O- groups). In this paper, FT-IR and Si-29 NMR spectroscopy have been used to elucidate whether the presence of Si-O-Zr or Si-O- is responsible for tetragonal phase stabilization. Moreover, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy have also been used to study the crystalline characteristics of the samples.