A new method for characterizing equilibrium pore shapes in ceramics

A new approach to characterizing the Wulff shape of ceramic materials has been developed, and applied to both undoped and Ti-doped sapphire. By exploiting microfabrication methods and hot pressing, identical arrays of internal micron-sized pores were produced. These pores undergo shape changes during high temperature annealing that can be followed in transparent ceramics by using optical microscopy. Ti additions substantially accelerated morphological change. After no further shape changes were evident, the internal pores were re-exposed by either fracture or by a serial sectioning procedure. Once re-exposed, atomic force microscopy was used to assess the pore shape. At a minimum, facets, if present, can be indexed. In an ideal case, a complete mapping of che Wulff shape may be possible.