Mechanochemical Changes of Weinschenkite‐Type RPO 4 ·2H 2 O (R = Dy, Y, Er, or Yb) by Grinding and Thermal Reactions of the Ground Specimens

It is reported that, on mechanochemical treatment, weinschenkite‐type RPO 4 ·2H 2 O (R = Dy, Y, or Er) gradually transforms into rhabdophane‐type RPO 4 · nH 2 O (n = 0.5 to 1) and weinschenkite‐type YbPO 4 ·2H 2 O into xenotime‐type YbPO 4 , at room temperature in air. Rhabdophane‐type YPO 4 ·0.8H 2 O and ErPO 4 ·0.9H 2 O obtained by grinding weinschenkite‐type RPO 4 ·2H 2 O (R=Y or Er) are new. The new rhabdophane‐type YPO 4 ·0.8H 2 O and ErPO 4 ·0.9H 2 O gradually transform to xenotime‐type YPO 4 and ErPO 4 when heated above 900°C (R = Y) and 700°C (R = Er) in air.