Some properties of a lead vanado-iodoapatite Pb10(VO4)6I2

A lead vanado-iodoapatite Pb10(VO4)6I2 was synthesized as a potential waste form to immobilize radioactive iodine and some thermal, mechanical and chemical properties were measured. Thermogravimetry–differential thermal analysis (TG–DTA) showed that the apatite was stable up to about 800 K. The thermal conductivity of the hot-pressed sample, with the theoretical density of 82%, increased gradually with increasing temperature from 0.65 W m−1 K−1 at room temperature to 0.78 W m−1 K−1 at 523 K. The micro-Vickers hardness and Youngʹs modulus were lower than those of a typical glass waste form. The leaching rate of iodine for apatite was two orders of magnitude higher than that of an AgI glass waste form. Despite the high leaching rate (compared to AgI embedded in glass), the high chemical stability up to 800 K and acceptable mechanical properties of this apatite suggest that it will be a good waste form when embedded in a suitable matrix material.