PREPARATION OF RHABDOPHANE-TYPE RPO(4)CENTER-DOT-NH(2)O (R=Y OR ER, N=0.7-0.8) BY POT-MILLING CHURCHITE-TYPE RPO(4)2H(2)O AT 20-25-DEGREES-C IN AIR

Rhabdophane-type (r-) RPO(4) . nH(2)O (R=Y or Er, n=0.7-0.8) was prepa red by pot-milling churchite-type RPO(4) . 2H(2)O (starting sample) at 20-25 degrees C in air. The duration of pot-milling the 30 g sample c auses the structural distortion and eventual disintegration that accom panies the formation of r-RPO(4) . nH(2)O, after 5 days (for R=Y, or 1 3 days for R=Er), through the intermediate stage of an amorphous phosp hate. For conversion of churchite into rhabdophane by a mechanical met hod, it is necessary to keep the H2O/RPO(4) (H/R) mole ratio around 1, such as 1.1-1.3 (amorphous phosphate) with a pot-mill (impact), or 0. 8-1.0 (rhabdophane coexisting with churchite) with a mortar (shearing) , before the formation of a single phase rhabdophane. When the 5 g sam ple was pot-milled, r-RPO(4) . nH(2)O (n=0.5-0.6) was obtained within 10 h, then changed to an amorphous phosphate after 1 day because the H /R ratio decreased abruptly to below 0.4.