Cerium Tungstate, Ce2(WO4)3, is obtained by mixing solutions of cerium sulphate and sodium tungstate and igniting the pale yellow precipitate produced. It yields crystals of density 6.514 at 12° C., with specific heat 0.0821 and melting-point 1089° C. It is also formed by adding cerium dioxide to fused sodium paratungstate and remains after washing with water.
The double tungstate, 4Na2O.Ce2O3.7WO3 or Na8Ce2(WO4)7, has been prepared by dissolving a mixture of cerium dioxide and tungsten trioxide in a fused mixture of sodium chloride and sodium tungstate, excess of the latter being present. An ammonium ceritungstate, 2(NH4)2O.Ce2O3.16WO3.2H2O, is obtained as a red transparent glass insoluble in water, when cerium hydroxide is boiled for eight hours with a solution of ammonium paratungstate, the mixture filtered, and the filtrate evaporated to dryness.
Yellow and red crystalline chlorotungstates have been produced by fusion of sodium tungstate and cerium chloride mixtures; and by the action of hydrogen chloride on tungsten and cerium dioxides. |