LOW TEMPERATURE SINTERING OF POLYCRYSTALLINE YTTRIA BY TRANSITION METAL ION DOPING

Sintering of (1 mol% Ni2+-1 mol% Er3+) or (1 mol% Mn2+-1 mol% Er3+)-doped Y2O3 polycrystals was investigated by conventional sintering at temperatures in the range 1200-1600 C. The sintering temperature required for full-densification decreased from 1600 to 1300 C by doping. The average grain size in Ni2+ or Mn2+-doped Y2O3 is twice as large as that in undoped Y2O3 at the examined sintering temperature. HRTEM observations and EDS analyses with a nano-sized probe showed that the doped transition metal ions segregated along the grain boundaries without amorphous layers and secondary phase particles. The segregated transition metal ions probably enhance grain boundary diffusion, and the sinterability of Y2O3 was accordingly improved.