Grain growth in Mn-doped ZnO

Grain growth in ZnO doped with 0.1 to 1.2 mol% Mn was investigated during i sothermal sintering from 1100 to 1300 degreesC in air. Mn doping promotes t he grain growth of ZnO during sintering, and this effect is enhanced by inc reasing the Mn doping level. The grain growth exponent is reduced from 3.4, for undoped ZnO, to 2.4, for ZnO doped with 1.2 mol% Mn: while the apparen t activation energy for grain growth is reduced from 200 kJ/mol, for undope d ZnO, to 100-150 kJ/mol, for Mn-doped ZnO. Electrical measurements suggest that an excess of Mn probably exists at grain boundaries, either as a very thin second phase or as an amorphous film, which could benefit grain bound ary diffusion, therefore promoting the grain growth of ZnO. (C) 2000 Elsevi er Science Ltd. All rights reserved.