Thermal conductivity of beta-Si3N4: II, effect of lattice oxygen

Dense beta-Si3N4 with various Y2O3/SiO2 additive ratios were fabricated by hot pressing and subsequent annealing, The thermal conductivity of the sint ered bodies increased as the Y2O3/SiO2 ratio increased. The oxygen contents in the beta-Si3N4 crystal lattice of these samples were determined using h ot-gas extraction and electron spill resonance techniques. A good correlati on between the lattice oxygen content and the thermal resistivity was obser ved. The relationship between the microstructure, grain-boundary phase, lat tice oxygen content, and thermal conductivity of beta-Si3N4 that was sinter ed at various Y2O3/SiO2 additive ratios has been clarified.