The present study investigated the effects of sulfuric acid doping on the structure, morphology, and sintering behavior of nano Y₂O₃ powders. The sintering kinetics of the resultant compacts during the initial sintering stage were assessed, using constant rates of heating (CRH). Compared to the undoped Y₂O₃ powder, the powder doped with sulfuric acid exhibited improved nano-scale uniformity in particle size and enhanced homogeneity in particle dispersion. The introduction of sulfuric acid as a dopant significantly boosted the densification rate of Y₂O₃ at temperatures exceeding ~1350 °C. This addition decreased the activation energy required for sintering and transformed the diffusion mechanism, shifting it from grain boundary (GB) diffusion to volume diffusion (VD) during the initial sintering stage. Microstructural and optical characterization of as-fabricated ceramics were employed to further evaluate the sintering behavior of powders. When being sintered at 1500 ℃ in vacuum, a homogeneous microstructure was observed in the ceramic derived from the doped Y₂O₃ powder, whereas large amounts of pores were presented in the undoped sample. At a sintering temperature of 1700 ℃ for 5 h, the undoped ceramic appeared opaque, while the doped sample exhibited remarkable transparency, achieving a transmittance of approximately 74% at a wavelength of 2000 nm.

Keywords: Sintering behaviour, Transparent ceramics, Y₂O₃ nano-powders, Sulfuric acid.