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 polycrystal was investigated by conventional sintering at the sintering temperature in a range from 1200 to 1600 degrees C. The sintering temperature required for full-densification decreased from 1600 to 1300 degrees C by the 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 indicated 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 the grain boundary diffusion, and the sinterability of Y2O3 was accordingly improved. (C)2009 The Ceramic Society of Japan. All rights reserved.