Doping effect on the flash sintering of Y₂O₃: Promotion of densification and optical translucency

Doping effect of 1 mol% divalent, trivalent or tetravalent cations on the flash sintering of Y₂O₃ was investigated under DC electric fields ranged from 0 to 1000 V cm⁻¹. The examined dopants were Mg²⁺, Sr²⁺, Al³⁺, La³⁺, Si⁴⁺, Ge⁴⁺ and Zr⁴⁺. The cation-doped Y₂O₃ specimens showed flash sintering at the DC fields greater than 300 V cm⁻¹. The onset temperature for the flash event in the Y₂O₃ depended on the doped cations; the onset temperature was reduced by doping the divalent cations, while that was increased by the trivalent or tetravalent cations-doping. The flash sintered, Al³⁺, Ge⁴⁺ or Si⁴⁺-doped Y₂O₃ bodies showed the relative density of greater than 98 %, and exhibited translucency. These cations decreased the electric conductivity of the Y₂O₃ green bodies, resulting in the relatively great electric power dissipation and enhanced diffusional mass transport during the flash event.