High-resolution electron microscope study of the ordered lead-calcium titanate ceramics
High-resolution electron microscopy (HREM) has been used to demonstrate the structural characteristics of ordered (Pb0.5Ca0.5) TiO3. The fine structure of both ordered and disordered domains was exposed in lattice level. It was shown that there are 1/2 {111}, 1/2 {110} and 1/2 {111} ordering coexisted in (Pb0.5Ca0.5) TiO3 and all of them are chemical ordering due to the layers of Pb2+ and Ca2+ cations align alternatively along different directions. For 1/2 {111} chemical ordering, a special type of boundary defined as “vernier boundary” was introduced.
The formation of dense layers of slag crust in a rotary furnace when normal electrocorundum sludge is used in the charge to make mullite-corundum fireclay depends on the chemical-mineral composition of the charge and the components of the crust, wetting processes, and the effect of lower compounds of titanium on the physico-chemical processes which take place.