Sr 1/2 Ce 5/14 □ 1/7 WO 4 ; a new modulated ternary scheelite compound
Résumé
Synopsis-A new ternary scheelite tungstate (Sr,Ce)WO 4 phase was synthesized, with a 2D incommensurately modulated structure linked to partial ordering of Sr, Ce cations and vacancies as was evidenced by high resolution electron microscopy. The bang gap of 3.2 eV makes it a promising violet emitting compound. Abstract-type the Abstract here (Style: IUCr Abstract) For the first time, a ternary tetragonal scheelite structure tungstate with strontium and cerium cations,(Sr,Ce)WO 4 , was synthesized. As much as 35 % Ce could be inserted in the structure, leaving 1/7 of the (Sr,Ce) cation sites vacant. Partial ordering of Sr and Ce, with atomic displacements, were evidenced by high resolution electron microscopy. 2D incommensurate modulations occur in this material, in small domains 20 nm in size. The band gap of this compound is significantly lower than the band gap of SrWO 4 and this was related to the distortions of WO 4 and (Sr,Ce)O 8 polyhedra. The bang gap value of 3.2 eV makes Sr 1/2 Ce 5/14 □ 1/7 WO 4 a promising candidate for violet luminescence.
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