Self-propagation high-temperature synthesis (SHS) was applied for the synthesis Of low-cost Si3N4 powder. The powder was purified and ground until its particle size reached submicron levels and its purity reached 98%. Using this pretreated powder, with alpha/beta = 60/40 content, fully dense Si3N4 ceramics, having improved mechanical properties, were obtained by liquid-phase sintering in the presence of (Y, La)(2)O-3-AlN. The mechanical properties achieved finally were as follows: strength, 784 MPa; hardness, 15.1 GPa: and fracture toughness, 5.2 MPa m(0.5). The behaviors of the SHS-Si3N4 powders before and after the pretreatment were compared. The relation between microstructure and mechanical properties of the sintered specimens and the effect of different beta content in the powder on the sintering process of Si3N4 were also studied. (C) 2008 Elsevier Ltd. All rights reserved.