Characterisation and electronic properties of some inorganic ion exchangers of the zirconium phosphate type containig transition-metal ions

Abstract

A series of transition-metal-ion forms of crystalline zirconium phosphate of general formula ZrM(PO₄)₂·4H₂O (M = Zn^II, Cu^II, Ni^II, Co^II, and Mn^II) has been characterised. The visible–near U.V. spectra of the copper, nickel, and cobalt species indicate the presence of an octahedral stereochemistry (tetragonally distorted in the case of Cu^II). The dehydration of the exchangers has been followed using thermal and X-ray powder techniques and electronic spectra. Magnetic-susceptibility measurements have also been used (where possible) to support structural assignment. Complete dehydration occurs only atca. 450 °C with a change in stereochemistry for the compounds of Ni^II and Co^II. At higher temperature the layer structure is lost and the materials become double phosphates, MZr(PO₄)₂. Possible stereochemistries for the anhydrous forms are discussed.