Sodium scandium arsenate, Na3Sc2(AsO4)3

Area of Science:

• Solid-state chemistry
• Materials science
• Crystallography

Background:

• Nasicon-type compounds are known for their potential in ion-exchange and solid-state electrolyte applications.
• Trisodium scandium phosphate (Na3Sc2(PO4)3) is a well-studied material in this class.
• Understanding structural variations in related arsenate compounds is crucial for materials design.

Purpose of the Study:

• To characterize the crystal structure and sodium ion environments in Nasicon-type trisodium discandium tris(arsenate), Na3Sc2(AsO4)3.
• To compare the structural features and sodium site occupancies with its phosphate analogue, beta-Na3Sc2(PO4)3.

Main Methods:

• Single-crystal X-ray diffraction was used to determine the crystal structure.
• Analysis of bond distances and coordination environments was performed.
• Comparison of sodium site occupancies with related materials.

Main Results:

• Na3Sc2(AsO4)3 exhibits a polyhedral network of vertex-sharing ScO6 octahedra and AsO4 tetrahedra.
• Average Sc-O bond distance is 2.089 Å, and average As-O bond distance is 1.672 Å.
• Two distinct sodium ion (Na+) sites were identified with occupancies similar to those in beta-Na3Sc2(PO4)3.

Conclusions:

• Nasicon-type Na3Sc2(AsO4)3 possesses a structure capable of hosting sodium ions within its framework.
• The structural similarity in sodium site occupancies suggests potential for analogous ion-transport properties compared to beta-Na3Sc2(PO4)3.
• This arsenate compound represents a new structural variant within the Nasicon family.