- The dehydration behavior and phase changes of crystalline -zirconium phosphate exchanged to increasing levels of Cu(II) content have been determined by thermal and X-ray methods. The fully exchanged compound is ZrCu(PO4)24H2O which loses 1 mole of water below 100C and this phase in turn loses another 1.5 moles below 200C forming ZrCu(PO4)21.5H2O. Additional mole of water is lost between 200 and 300C yielding a solid with a poorly defined X-ray pattern. However, annealing in this temperature range produces a well crystallized phase (termed phase G). This phase has a variable water content ranging from 0.5 to zero moles and long heating times at 400-450C are required to achieve the anhydrous state. In the region of low copper contents the phases formed are solid solutions which resemble -zirconium phosphate phases. 1980.