Low-temperature synthesis and sintering of γ-Y2Si2O7

In this article, a novel pressureless solid-liquid reaction method is presented for preparation of yttrium disilicate (gamma-Y2Si2O7). Single-phase gamma-Y2Si2O7 powder was synthesized by calcination of SiO2 and Y2O3 powders with the addition of LiYO2 at 1400 degrees C for 4 h. The addition of LiYO2 significantly decreased the synthesis temperature, shortened the calcination time, and enhanced the stability of gamma-Y2Si2O7. The sintering of these powders in air and O-2 was studied by means of thermal mechanical analyzer. It is shown that the gamma-Y2Si2O7 sintered in oxygen had a faster densification rate and a higher density than that sintered in air. Furthermore, single-phase gamma-Y2Si2O7 with a density of 4.0 g/cm(3) (99% of the theoretical density) was obtained by pressureless sintering at 1400 degrees C for 2 h in oxygen. Microstructures of the sintered samples are studied by scanning electron microscope.