Enhanced sodium ion mobility in sodium tellurosilicates and crystal structures of Na 4 SiTe 4 and Na 10 Si 2 Te 9 with isolated [SiTe 4 ] 4- tetrahedra and isolated Te 2- anions

• Published in: Dalton transactions : an international journal of inorganic chemistry 2024-09, Vol.53 (37), p.15630-15637
• Main Authors: Kamm, Franziska, Pielnhofer, Florian, Schlosser, Marc, Pfitzner, Arno
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d4dt01717j

The sodium tellurosilicates Na SiTe , Na Si Te , Na Si Te and Na Si Te were synthesized by ball milling and subsequent high temperature solid state reactions and analyzed by electrochemical impedance spectroscopy. All compounds show moderate to remarkable sodium ion conductivities. The crystal structures of the novel materials Na SiTe and Na Si Te were determined by X-ray diffraction. Both compounds represent new structure types with isolated SiTe tetrahedra. The crystal structure of Na Si Te exhibits a single telluride anion besides two SiTe tetrahedra. Na SiTe crystallizes in the cubic space group 3̄ (no. 205) with lattice parameters = 13.0312(1) Å and = 2212.84(2) Å . Na Si Te crystallizes in the orthorhombic space group 2 (no. 33) with lattice parameters = 12.8235(7) Å, = 14.8398(8) Å, = 12.9530(7) Å and = 2464.9(2) Å . The presence of two different anionic units makes this compound stand out from other alkali chalcogenotetrelates. The electronic structure of all compounds was investigated by density functional theory, revealing their semiconducting behaviour.