Effect of lattice defects on the thermal conductivity of β-Si3N4

Spark Plasma Sintering of fine alpha-silicon nitride ceramics with LAS for spatial applications

“…Nevertheless, the value of 21.4 W m −1 K −1 is certainly very low compared to previous reports done by Peng et al 11,12 by using non-oxide additives (MgSiN 2 ). This reduction could be attributed to the presence of oxygen 23,24 in LAS or LAS/Y 2 O 3 -Al 2 O 3 compositions and the development of very fine equiaxed ␣-phase microstructures instead of elongated ␤-grains.…”

Highly Porous Silicon Nitride Foam Prepared Using a Route Similar to the Making of Aerated Food

“…Si 3 N 4 is a kind of ceramic with high thermal conductivity. The reported thermal conductivities of Si 3 N 4 are generally in the range of 20–150 W/(m·K), depending on the fabricating route .…”

Potential use of only Yb2O3in producing dense Si3N4ceramics with high thermal conductivity by gas pressure sintering

“…However, little attention was paid to the thermal conductivity of Si 3 at room temperature [1]. A considerable amount of work resulted in significantly increased thermal conductivities of Si 3 N 4 ceramics of above 100 W m −1 K −1 [2][3][4][5][6][7]. Enhanced thermal conductivity opens up new technological applications of Si 3 N 4 as substrates for integrated circuits and heat sinks in electronic devices.…”

“…The sintering additives determine the densification, phase transformation, grain growth and characteristics of the grain boundary phase; thus, the use of effective sintering additives is crucial for improving the thermal and mechanical properties of Si 3 N 4 ceramics. The key issues in enhancing the thermal conductivity of β-Si 3 N 4 ceramics are the complete densification, purification of β-Si 3 N 4 grains and a reduced amount of grain boundary phases; all of which are dependent on the sintering additives and sintering techniques [2,7]. Dissolved O and Al in the β-Si 3 N 4 lattice are the two main impurities that lower the thermal conductivity of β-Si 3 N 4 via phonon-defect scattering, and thus the use of SiO 2 and Al 2 O 3 additives should be avoided [4,11].…”

“…In gas pressure sintering, a higher N 2 pressure allows the sintering of powder compacts at higher temperatures without significant thermal decomposition. Higher temperatures not only favor β-Si 3 N 4 grain growth but also make it possible to reduce the amount of sintering additives and to use more stable compounds [3,6] [16][17][18] or ZrO 2 [7].…”