New Mixed-Valent Iron (II/III) Phosphates, Cu3-xFe4+x(PO4)6

The aim of this work has been to investigate the influence of two coloring dopant ions on the ZrSiO4 host lattice. Pure, vanadium-doped and praseodymium-doped zircon powders have been synthesized by the ceramic method and analyzed using X-ray diffraction and the perturbed angular correlations (PAC) hyperfine technique, which probes the nearest environments of zirconium ions. XRD results indicated that vanadium and praseodynamium incorporations in the host lattice result in crystalline solid solutions. In turn, PAC information allowed in both cases the determination of two contributions to the hyperfine interaction. In the case of vanadium-doped zircon, V4+ substitutes mainly for Zr4+ and in a minor fraction for Si4+ or else it localizes at a tetrahedral interstitial site. In praseodymium-doped zircon, a low fraction of Pr4+ cations locate at Zr4+ sites. A slight modification of the zircon lattice is probably caused by the incorporation of the remaining cations at tetrahedral interstitial sites of the solid solution