DIRECTED CRYSTALLIZATION OF SELECTED ALUMINOPHOSPHATE HYDRATES BY PH CONTROL

Is a systematination of the synthesis of aluminophosphates possible? A step away from trial and error syntheses is permitted by an investiga tion of the link between the structure of aluminophosphate hydrates an d the structure of the predominant species in the gel precursor. The r atio Al(O)/Al(T), i.e., the ratio of octahedrally to tetrahedrally coo rdinated aluminum, depends on the pH of the gel precursor. Thus, it is demonstrated that the crystallization reaction can be directed to the desired aluminophosphate phase simply by controlling the gel precurso r pH.