CsAlSi5O12: a possible host for 137Cs immobilization

CsAlSi5O12 exhibits more acid resistance than pollucite (CsAlSi2O6). At pH values of 1.02 and 1.40, the extraction of Cs from CsAlSi5O12 at 250C was approximately proportional to the square root of leach time. The Cs extraction at 250C varied as [H+]036 over the pH range of 1 to 6. Also, the Cs extraction in various brines at 3000C/30 MPa was comparable with that for pollucite. CsAlSi5O12 can be crystallized at about 10000C from calcines if a small amount of CaO is present, but in the absence of such sintering acids, crystallization temperatures of about 14000C are necessary. Compatibility data were also obtained with respect to several other phases with which CsAlSi5O12 might be expected to coexist in tailored ceramics designed for high-level defense waste