A novel method to synthesize pure-phase Si2N2O powders in a fluidized bed reactor
Si 2 N 2 O ceramic, an emerging functional and structural material, has a wide range of applications. However, the preparation of pure-phase Si 2 N 2 O powder remains challenging due to the mass transfer resistance and undesirable side reactions in the conventional methods. Herein, a novel molecular approach combined with the decomposition process has been developed to synthesize pure-phase Si 2 N 2 O powders. The hydrated Si(NH) 2 precursors were synthesized through the chemical vapor deposition (CVD) of SiCl 4 , NH 3, and humidified N 2 in a fluidized bed reactor (FBR) in two steps. Then, the hydrated Si(NH) 2 precursors were decomposed into amorphous and subsequently transformed into crystalline powders under different temperatures and time. It was found that the molar ratio of N/O of the hydrolyzed Si(NH) 2 can be controlled by N 2 ventilation time and played an important role in synthesizing high pure Si 2 N 2 O powder. When it varied from 2.5:1 to 2:1, pure-phase Si 2 N 2 O powder was obtained after heat treatment at 1300–1500 °C, which features a big tolerance for N/O ratios. This newly developed method offered a chance for the preparation of high-quality Si 2 N 2 O powder with high efficiency and low cost.
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