Hydrothermally assisted synthesis of pure-phase and well-dispersed forsterite nanopowders

Abstract

This study introduces a hydrothermal method for the synthesis of forsterite nanopowders. The resultant precursors obtained by hydrothermal pretreatment exhibited a much higher specific surface area (311.37 m2/g) than the precursor obtained by the conventional solid-state method. When the precursors were calcined at 1000 °C for 2 h, single-phase forsterite nanopowders with an average grain size of approximately 78 nm and an average particle size of approximately 234 nm were obtained. During the calcination process, the release of abundant water from the decomposition of intermediates Mg(OH)2 at ~380 °C and Mg3Si2O5(OH)4 at ~581 °C enhanced the dispersibility of the powder. Additionally, the formation of Mg3Si2O5(OH)4 with the Mg/Si ratio of approximately 2: 1 may have favored a pure forsterite phase at low temperatures. When the as-synthesized nanopowders were used as starting materials, the fabricated Mg2SiO4 nanocrystalline ceramics exhibited 93.7% of their theoretical density and a relatively narrow grain size distribution, with an average grain size of approximately 310 nm.