Sr1/2Ce5/14□1/7WO4: a new modulated ternary scheelite compound

Rafael Hernandez Damascena Dos Passos; Madjid Arab; Carlson Pereira de Souza; Christine Leroux

doi:10.1107/S2052520617002827

Sr_1/2Ce_5/14□_1/7WO₄: a new modulated ternary scheelite compound

Acta Crystallogr B Struct Sci Cryst Eng Mater. 2017 Jun 1;73(Pt 3):466-473. doi: 10.1107/S2052520617002827. Epub 2017 Jun 1.

Authors

Rafael Hernandez Damascena Dos Passos¹, Madjid Arab¹, Carlson Pereira de Souza², Christine Leroux¹

Affiliations

¹ Université de Toulon, CNRS, IM2NP, BP 20132, La Garde CEDEX, F- 83957, France.
² Universidade do Rio Grande de Norte, DEQ/PPGEQ-LMNRC, Campus Universitario, Lagoa Nova 59072-970 Natal, Brazil.

PMID: 28572556
DOI: 10.1107/S2052520617002827

Abstract

For the first time, a ternary tetragonal scheelite structure tungstate with strontium and cerium cations, (Sr,Ce)WO₄, was synthesized. As much as 35% Ce could be inserted into the structure, leaving 1\over 7 of the (Sr,Ce) cation sites vacant. Partial ordering of Sr and Ce, with atomic displacements, were shown by high-resolution electron microscopy. Two-dimensional 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 SrWO₄ and this was related to the distortions of WO₄ and (Sr,Ce)O₈ polyhedra. The band gap value of 3.2 eV makes Sr_1/2Ce_5/14□_1/7WO₄ a promising candidate for violet luminescence.

Keywords: X-ray diffraction; band gap; high-resolution electron microscopy; ordering; scheelite; simulations.