K2ScSn(AsO4)3: an arsenate-containing langbeinite.

Area of Science:

• Inorganic Chemistry
• Crystallography
• Materials Science

Background:

• Langbeinites are a class of inorganic compounds with a characteristic crystal structure.
• Arsenate-containing compounds are of interest for various material properties.
• Previous characterization of langbeinites has not included arsenate anions.

Purpose of the Study:

• To characterize the novel compound dipotassium tri-mu-arsenato-scandium(III)tin(IV).
• To determine the crystal structure and cation distribution within the langbeinite framework.
• To investigate the bonding characteristics and structural features of this new material.

Main Methods:

• Single-crystal X-ray diffraction was employed for structural determination.
• Crystallographic symmetry and site occupancies were analyzed.
• Bond-valence-sum calculations were performed to assess ionic bonding.

Main Results:

• The compound crystallizes in the aristotype P2(1)3 cubic symmetry.
• Scandium(III) and Tin(IV) ions exhibit slight segregation across octahedral sites.
• Potassium ions were found to be underbonded, and oxygen atoms showed large anisotropic displacement parameters.
• The crystal was identified as a merohedral twin.

Conclusions:

• Dipotassium tri-mu-arsenato-scandium(III)tin(IV) is the first characterized arsenate langbeinite.
• The study provides detailed structural and bonding insights into this novel inorganic compound.
• Structural features, including cation distribution and bonding, are consistent with other langbeinites, with notable exceptions in potassium ion bonding.