KSm(MoO(4))(2), an incommensurately modulated and partially disordered scheelite-like structure

Area of Science:

• Crystallography
• Materials Science
• Solid State Chemistry

Background:

• Scheelite-like structures exhibit complex modulated phases.
• Understanding cation ordering is crucial for materials properties.

Purpose of the Study:

• To refine the crystal structure of KSm(MoO(4))(2).
• To investigate the cation disorder and its impact on the structure.
• To compare cation ordering with related compounds.

Main Methods:

• Synchrotron radiation powder diffraction.
• Rietveld refinement.
• Transmission electron microscopy (TEM).

Main Results:

• The KSm(MoO(4))(2) structure was refined in the monoclinic superspace group I2/b(alphabeta0)00.
• Anisotropic microstrain line-broadening explained satellite reflection broadening.
• Partial disorder of K and Sm cations was modeled using harmonic and complex crenel functions, revealing a compositional wave distribution.

Conclusions:

• The refined structure provides detailed insights into the modulated nature of KSm(MoO(4))(2).
• The cation ordering significantly influences the observed structural features.
• Comparison with KNd(MoO(4))(2) highlights differences in cation ordering behavior.