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 (γ-Y₂Si₂O₇). Single-phase γ-Y₂Si₂O₇ powder was synthesized by calcination of SiO₂ and Y₂O₃ powders with the addition of LiYO₂ at 1400 °C for 4 h. The addition of LiYO₂ significantly decreased the synthesis temperature, shortened the calcination time, and enhanced the stability of γ-Y₂Si₂O₇. The sintering of these powders in air and O₂ was studied by means of thermal mechanical analyzer. It is shown that the γ-Y₂Si₂O₇ sintered in oxygen had a faster densification rate and a higher density than that sintered in air. Furthermore, single-phase γ-Y₂Si₂O₇ with a density of 4.0 g/cm³ (99% of the theoretical density) was obtained by pressureless sintering at 1400 °C for 2 h in oxygen. Microstructures of the sintered samples are studied by scanning electron microscope.