| Abstract: | A New Structure Type for the Rare Earth Oxotungstate FeCe(WO4)W2O8 = FeCe(WO4)3 Single crystals of the hitherto unknown compound FeCe(WO4)3 have been prepared by crystallization from melts of Fe2O3, CeO2 and WO3. It crystallizes with triclinic symmetry, space group P1 , a = 7,486(3); b = 7,528(1); c = 16,502(4) Å, α = 101,00(2); β = 96,62(3); γ = 98,62°; Z = 2. Tungsten shows octahedral and tetrahedral coordination by oxygen. The crystal structure is characterized by layers related to the Scheelite and Wolframite type. Thermogravimetric measurements led to a lost of oxygen during reaction. It results in a decrease of the oxidation states of Fe3+ and Ce4+ respectively, as will be discussed using magnetic measurements and calculations of the Coulomb terms of lattice energy. The structure contains a one-fold coordinated oxygen. |
