Since the past twenty years,high powder solid-state laser development was accompanied by a growing interest in transparent ceramics as amplifier media.Nevertheless,transparent ceramics used for this kind of application should respect numerous criteria.At first,the ceramic material should present a thermal conductivity as high as possible(> 6-8 W.m-1.K-1)and a thermal expansion coefficient sufficiently low(< 10.10-6 K-1)to be resistant to thermal shock and to ensure high repetition rate during high power lasing operation.