Oxygen Content in ß‐Si3N4 Crystal Lattice

Abstract

and subsequent acid treatments that removed the secondary phases. The lattice oxygen contents of these crystals were determined by the hot-gas extraction method to be 0.258 ± 0.006 and 0.158 ± 0.003 wt% for the additive compositions of Y 2 O 3 :SiO 2 = 1:2 and 2:1, respectively. The oxygen dissolved in the ␤-Si 3 N 4 crystal lattice as much as in the ␣-Si 3 N 4 crystral lattice prepared by the chemical vapor deposition process and in the AlN crystal lattice that exhibited high thermal conductivity.

Effect of amounts and types of silicon nitride on thermal conductivity of Si₃N₄/epoxy resin composite

“…SEM images of the composite material were obtained by background-scatter electron (BSE). The amount of oxygen impurities dissolved in the Si 3 N 4 particles, or lattice oxygen content, was determined by the method reported by Kitayama et al 18) using a hot-gas extraction analyzer (Model TC-436 and EF-400, LECO Co., USA). In this method, the sample was placed in a graphite crucible, followed by heating to 2500°C in 5 min in a flowing argon atmosphere.…”

“…18) Kitayama et al reported a correlation between lattice oxygen content and thermal resistivity (the inverse of thermal conductivity) of crystalline ¢-Si 3 N 4 .…”

Effect of post-sintering heat-treatment on thermal and mechanical properties of Si3N4 ceramics sintered with different additives

“…Three measurements were performed for all samples and the average is used as the measured value. Amount of oxygen distributed in Si 3 N 4 lattice (lattice oxygen) was approximated by Gaussian peak separation of the evolution curve during heating after Kitayama et al 9 using the HF-treated powders (46% HF, 3 h at 333 K and 50% H 2 SO 4 , 6 h at 373 K).…”

Thermal Conductivity of β‐Si3N4: III, Effect of Rare‐Earth (RE = La, Nd, Gd, Y, Yb, and Sc) Oxide Additives

“…It was found that grain growth of ␤-Si 3 N 4 shifts from interfacial-reaction- controlled to diffusion-controlled as the ionic radius of the rareearth element decreases, and later that the activation energy for the interfacial reaction linearly decreases with decreasing ionic radius. 24 This is the reason why the phase transformation rate of a sample sintered with La 2 O 3 , the largest among the rare-earth ions, is extremely slow, and why mean grain size (Ϸ mean grain width) increases with decreasing ionic radius of the rare-earth ions. The reason why the mean grain sizes of samples sintered with Yb 2 O 3 and Sc 2 O 3 are somewhat smaller than Y 2 O 3 , even though their grain growth is expected to be more diffusion-controlled, can be attributed to their higher viscosity of the liquid phase due to their higher cationic field strength.…”