New triple molybdate Rb2AgIn(MoO4)3: synthesis, framework crystal structure and ion-transport behaviour.
Acta Crystallogr C Struct Chem
; 74(Pt 12): 1603-1609, 2018 12 01.
Article
en En
| MEDLINE
| ID: mdl-30516143
ABSTRACT
A new triple molybdate, Rb2Ag1+3xIn1-x(MoO4)3 (0 ≤ x ≤ 0.02), was found in the course of a study of the system Rb2MoO4-Ag2MoO4-In2(MoO4)3 and was synthesized as both powders and single crystals by solid-state reactions and spontaneous crystallization from melts. The structure of Rb2Ag1+3xIn1-x(MoO4)3 (x â 0.004) is of a new type crystallizing in the centrosymmetric space group R-3c [a = 10.3982â
(9), c = 38.858â
(4)â
Å, Z = 12 and R = 0.0225] and contains (In,Ag)O6 octahedra and distorted Ag1O6 trigonal prisms linked by common faces to form [Ag(In,Ag)O9] dimers connected to each other via MoO4 tetrahedra into an open three-dimensional (3D) framework. Between two adjacent [Ag(In,Ag)O9] dimers along the c axis, an extra Ag2O6 trigonal prism with about 1% occupancy was found. The Ag1O6 and Ag2O6 prisms are located at levels of z â 1/12, 1/4, 5/12, 7/12, 3/4 and 11/12, and can facilitate two-dimensional ionic conductivity. The 12-coordinate Rb atoms are in the framework cavities. The structure of Rb2AgIn(MoO4)3 is a member of the series of rhombohedral 3D framework molybdate structure types with a â 9-10â
Å and long c axes, which contain rods of face-shared filled and empty coordination polyhedra around threefold axes. Electrical conductivity of ceramics is measured by impedance spectroscopy. Rb2AgIn(MoO4)3 undergoes a `blurred' first-order phase transition at 535â
K with increasing electrical conductivity up to 1.1 × 10-2â
Sâ
cm-1 at 720â
K. Thus, the compound may be of interest for developing new materials with high ionic conductivity at elevated temperatures.
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Revista:
Acta Crystallogr C Struct Chem
Año:
2018
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Article