Complex interrupted tetrahedral frameworks in the nitridosilicates M7Si6N15 (M = La, Ce, Pr)

Area of Science:

• Solid-state chemistry
• Materials science
• Inorganic chemistry

Background:

• Nitridosilicates are a class of inorganic compounds containing silicon, nitrogen, and other elements.
• Understanding their structure-property relationships is crucial for developing new materials.

Purpose of the Study:

• To synthesize and characterize a new nitridosilicate structure type.
• To investigate the crystal structure and properties of M(7)Si(6)N(15) compounds where M = La, Ce, and Pr.

Main Methods:

• High-temperature synthesis in a radio-frequency furnace (1550-1625 °C).
• Single-crystal X-ray diffraction for crystal structure determination.
• Powder diffraction and high-resolution transmission electron microscopy (HRTEM) for structural analysis.
• Magnetic susceptibility measurements for Ce(7)Si(6)N(15).

Main Results:

• A new nitridosilicate structure type, M(7)Si(6)N(15), with an interrupted framework was identified.
• Ordered triclinic and disordered trigonal structures were observed for Ce(7)Si(6)N(15).
• The structure consists of corner-sharing SiN(4) tetrahedra forming 12-rings and finite chains.
• Ce(7)Si(6)N(15) exhibits paramagnetic behavior, confirming Ce(3+) oxidation state.

Conclusions:

• The M(7)Si(6)N(15) compounds represent a novel structural motif in nitridosilicate chemistry.
• The presence of both ordered and disordered crystallites highlights complex structural phenomena.
• The findings contribute to the fundamental understanding of nitridosilicate frameworks and their properties.