Efforts were made to improve understanding by (a) fabrication and analysis of individual boundaries, (b) improved control and simplification of boundary chemistry (c) systematic investigation of properties (e.g., I-V, DLTS, DO and DM) as a function of boundary structure and chemistry and (d) development of appropriate energy band, defect and diffusion models. Following this approach, preliminary results suggested that lattice defects played critical roles in controlling both the electrical and diffusive properties of the boundaries while the additives appeared to act in supportive manner by activating the key lattice defects particularly with respect to the electrical activity of the boundaries.

ZnO Grain Boundaries: Electrical Activity and Diffusion. Tuller, H.L.: Journal of Electroceramics, 2000, 4[1], 33-40