The features of anomalous behaviour of silica glass doped with titanium oxide are discussed. The low thermal expansion of silica glass is considered on the base of the idea about polymorphous transformations in meta stable-glass structures. The analogy of these transformations to structural transitions of martensite type in metallic alloys is assumed. The effect of TiO2-doping on the structure and the intrinsic strength of silica glass fibres is studied. The structural (intrinsic) strength has been found to decrease by about 15% compared to that of non doped silica glass. This decrease of strength is assumed to be accounted for the incorporation of a part of titanium ions into glass structure with six fold coordination resulting in weakening the connectivity of a glass anionic network.
