Synthesis and Properties of Willemite,Zn2SiO4, and M2+:Zn2SiO4 (M = Co and Ni)

Fine particles of willemite, -Zn₂SiO₄, were prepared by both solution combustion and sol-gel methods. Both processes yield single-phase, large-surface area (26- and 78-m²/g), sinteractive willemite powders. Thermal evolution of crystalline phases was studied using X-ray powder diffraction patterns. The combustion method favors low-temperature formation of willemite compared to the sol-gel method. The powders, when uniaxially pressed and sintered at 1300°C, achieved 78–80% theoretical density. The microstructures of the sintered body show the presence of equiaxed 0.5- to 4-m grains. Blue pigments of willemite doped with Co²⁺ and Ni²⁺ were also prepared by the combustion process.