An EXAFS Investigation on Copper(I-II) Related Nasicon-Type Phosphates

Abstract

An extended X-ray absorption fine structure study at the copper K-edge of Nasicon-type phosphates with formulas Cu1M2(PO4)3 (M = Ti, Zr), A1-xCuIxZr2(PO4)3 (0 < x ≤ 1, A = Na; x = 0.5, A = H) and CuII0.5M2(PO4)3 (M = Ti, Zr) is reported. For Cu1Zr2(PO4)3, H0.5CuI0.5Zr2(PO4)3, and Na1-xCuIxZr2(PO4)3 (0 <: x ≤ 1) copper pairs have been evidenced (Cu1-Cu1 = 2.40 Å) in the M1 site of the Nasicon structure. In contrast, for the copper(II) phosphates, the Cu2+ ions are surrounded by four oxygen atoms at about 1.95 Å. Copper distribution in these various materials is discussed in relation to structural parameters.