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The strongly defective double perovskite Sr 11 Mo 4 O 23 : crystal structure in relation to ionic conductivity
Author(s) -
López Carlos A.,
Pedregosa José C.,
Lamas Diego G.,
Alonso José A.
Publication year - 2014
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576714013491
Subject(s) - tetragonal crystal system , octahedron , crystal structure , crystallography , perovskite (structure) , neutron diffraction , ionic conductivity , ionic bonding , chemistry , phase (matter) , powder diffraction , crystal (programming language) , materials science , ion , organic chemistry , electrode , electrolyte , computer science , programming language
The crystal structure and ionic conductivity properties of a novel microcrystalline Sr 11 Mo 4 O 23 ceramic material are presented. This material has been prepared by thermal treatment up to 1473 K, in air, of previously decomposed citrate precursors. The complex crystal structure was refined from combined X‐ray powder diffraction and neutron powder diffraction data. The formula of this phase can be rewritten as Sr 1.75 □ 0.25 SrMoO 5.75 , highlighting the relationship with double perovskites A 2 B ′ B ′′O 6 . At room temperature, the crystal structure is tetragonal in space group I 4 1 / a , with a = 11.6107 (6) Å, c = 16.422 (1) Å and V = 2213.8 (2) Å 3 . The crystal network contains O anion and Sr cation vacancies. The structure is complex, with Sr, Mo and O atoms distributed over four, two and six distinct Wyckoff sites, respectively. Only one of the Sr sites (SrO 6 ) corresponds to the octahedral network; one of the two MoO 6 types of octahedra is axially distorted. The three other Sr positions occupy the A site with higher coordination. There is an occupational deficit of O atoms of 22 (4)%. This defective framework material presents an interesting ionic mobility, enhanced above 773 K owing to a further reduction in the oxygen content.