Structure, Optical Properties, and Magnetism of the Full Zn1–xCuxWO4 (0 ≤ x ≤ 1) Composition Range

Microcrystalline and submicrometer powders of Zn1–xCuxWO4 (0 ≤ x ≤ 1) have been prepared by a solid-state synthesis from stoichiometric quantities of the constituent d-block metal oxide and tungsten oxide as well as from a Pechini sol–gel synthesis starting from the d-block metal nitrate and ammonium metatungstate. The stoichiometry of the product is confirmed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. X-ray diffraction shows that for the entire range of compositions, a single-phase product crystallizes in the wolframite structure, with a symmetry-lowering transition from P2/c to P1 at x = 0.20, concomitant with the first-order Jahn–Teller distortion of Cu2+. Far-IR spectroscopy corroborates that symmetry lowering is directly related to the tetragonal distortion within the CuO6 octahedra, with the Zn–O Au symmetry mode at 320 cm–1 (x = 0) splitting into two stretches at 295 and 338 cm–1 (x = 0.3). UV–vis–NIR spectroscopy shows an optical absorption edge characteristic ...