Photothermal methods have turned out to be a very interesting way to carry
out the study of complex materials such as functional ceramics (polycrystal
line diamond - aluminium nitride zirconia) whose thermal properties have to
be determined at different spatial scales if one wants to optimize their t
hermal behaviour. Results at microscopic scales (diffusivity at the scale o
f one single grain and thermal barriers at grain boundaries) and at macrosc
opic scales (averaged value of the diffusivity on a large number of grains
and interfaces) are presented.