Low-temperature synthesis/densification and properties of Si_2N_2O prepared with Li_2O additive

摘要

Dense Si_2N_2O was successfully synthesized using 2mol percent Li_2O as an additive by a hot-pressing method at 1500 deg C. Compared to other metal oxide additives, Li_2O can significantly decrease the sintering temperature of Si_2N_2O, which is ascribed to the lower melting point of Li_2O-SiO_2 and the formation of less viscous liquid phase. Increasing Li_2O content has no apparent influence on the mechanical and dielectric properties of dense Si_2N_2O, which is due to the easy evaporation of Li_2O at sintering temperature. The mechanical properties of Si_2N_2O with Li_2O additive arc comparable to those of Si_2N_2O synthesized with other additives. The as-prepared bulk Si_2N_2O with 2mol percent Li_2O additive exhibits both low dielectric constant (6.17 at 1 MHz) and loss tangent (0.0008 at 1 MHz) and combines good mechanical performance, indicating it is a potential high-temperature structural/functional material.