Kogure and co-workers have published several papers reporting the stacking structures of various 2:1 layer phyllosilicates (e.g. aspidolite, Kogure et al. (2004); wonesite, Kogure et al. (2005); pyrophyllite, Kogure et al. (2006)), mainly by using high-resolution transmission electron microscopy (HR-TEM). However, there is ambiguity in wording that refers to the lateral displacement between two tetrahedral sheets across the interlayer regions. Zvyagin et al. (1969) used the symbol “τ” for this displacement, which describes the structures of pyrophyllite and talc, but no universally accepted wording was used for other 2:1 phyllosilicates or 1:1 phyllosilicates.

The purpose of this study was to develop a simple and economic method for the preparation of porous bioceramics with controllable macrostructure. Raw materials, including very small organic foam balls as the pore-creating reagent, wax (or paraffin) as the solvent, and oleic acid as the surface active agent, were selected along with bioactive materials such as β-TCP ceramic powder as the main component. The selected components were mixed into a slurry at 30–120ºC and shaped into a green body with a hot die-casting machine at 30–90ºC. The green body was then sintered and porous bioceramics were obtained. The main characteristics of porous bioceramics such as weight loss, compressive strength, connection and size of pores, percolation rate of water, apparent porosity and bulk density were measured. The results indicated that the apparent porosity and the specific surface area were large; the pores were connected in three dimensions and the compressive strength was >1.6 MPa. This study demonstrated that the methods used here are simple and effective in generating porous bioceramics with controllable macrostructures.