C. Pelissonnier-grosjean et al., Thermal resistance of grain boundary interfaces in polycrystalline aluminum nitride, J PHYS IV, 9(P4), 1999, pp. 201-206
Polycristalline aluminium nitride exhibit poor thermal conductivity in comp
arison with that of monocristalline nitride. This is due to microstructural
features specific of ceramic materials such as impurities, secondary phase
s or grain boundaries... In an attempt to understand the effect of grain bo
undaries on the macroscopic conductivity of yttria doped polycristalline al
uminium nitride, local thermal measurements were achieved on two materials
of quite different microstructure. Thermal investigation was performed by m
eans of photoreflectance microscopy, a photothermal variant which allows a
spatial resolution of a few micrometers. The experimental results are discu
ssed in terms of thermal discontinuities or thick interphases of poor therm
al properties at the boundaries. They are also linked to grain boundaries m
icrostructural features. Moreover, the induced effect of each thermal behav
iour on the macroscopic conductivity evaluation is presented.