Investigation on the reaction sequences and properties of β-eucryptite ceramic fabricated by a novel solid state reaction route from hydroxides

Abstract β-eucryptite (β-LiAlSiO 4 ) ceramic has been fabricated via a novel solid state reaction method by taking hydroxides LiOH∙H 2 O, Al(OH) 3 and SiO 2 as reactants. The changes of mass, heat and evolution of crystal phases during the reaction process, as well as the reaction sequences, sintering characteristic, micro-morphology and thermal expansion property of the β-LiAlSiO 4 ceramic have been fully studied. The results show that a highly reactive intermediate phase γ-Al 2 O 3 forms after heating Al(OH) 3 over 550℃. γ-Al 2 O 3 preferentially reacts with dehydrated LiOH to form LiAlO 2 , which further reacts with SiO 2 to produce β-LiAlSiO 4 at 700℃. Single-phase β-LiAlSiO 4 powders can be obtained at a low temperature of 950℃. The β-LiAlSiO 4 ceramic sintered at 1200℃ for 1 h shows dense and less cracked microstructure with zero coefficient of thermal expansion α=-0.5 × 10 -6 /K, which is expected to be a promising material in laser gyroscope and telescope fields.