Strontium Iodoapatite

Description

Strontium iodoapatite is of academic interest because of the large size of the I^- ion compared to the other halide ions. However, the thermodynamic functions determined for the alkaline earth apatite series preclude the formation of a stable iodoapatite because of the cationic size of Sr²⁺ or Ba²⁺ is too small relative to that of the iodide ion which must fit upon the c-axis of the structure next to the triads of Sr²⁺ or Ba²⁺ at (000), (010), (011), and (001) positions in the lattice. Such crystals relevant to radioactive waste management include fluorapatite, and, in the end, iodoapatite, which should be able to immobilize the radioactive species,¹²⁹I.
However, a lead vanado-iodoapatite Pb10(VO4)6I2 has been synthesized as a potential waste form to immobilize radioactive iodine and some thermal, mechanical and chemical properties were measured. TG–DTA showed that the apatite was stable up to about 800 K.