Analogies between the mechanical and dielectric properties in the ceramic material type oxide

It is well-known that one of the principal difficulties which limit the development of ceramics is their intrinsically brittle nature. In this work we were interested to the study of the single crystal alumina tenacity measured by the Vickers indentation technique in the aim to highlight certain factors responsible for this brittleness. After having defined a reliable protocol of measurement on pure sapphire, we studied the effect on tenacity of the structural defects introduced into the same single crystal by friction and by both X-rays and UV irradiations. The obtained results reveal the importance of these defects which behave, in this case, like trapping sites of electric charges and affect in an important way tenacity of material.