The Phosphidosilicates AE₂ Li₄ SiP₄ (AE=Ca, Sr, Eu) Ba₄ Li₁₆ Si₃ P₁₂

Area of Science:

• Solid-state chemistry
• Materials science
• Inorganic chemistry

Background:

• Quaternary phosphidosilicates are compounds containing phosphorus and silicon.
• Understanding their structure-property relationships is crucial for developing new materials.

Purpose of the Study:

• Synthesize and characterize novel quaternary phosphidosilicates AE2 Li4 SiP4 and Ba4 Li16 Si3 P12.
• Investigate their crystal structures and potential for lithium-ion conductivity.

Main Methods:

• Synthesis via heating elements and Li3P under argon.
• Crystal structure determination using single crystal X-ray diffraction.
• Solid-state nuclear magnetic resonance (NMR) spectroscopy (31P, 29Si, 7Li).
• Electrochemical impedance measurements.

Main Results:

• Two new structure types were discovered: layered AE2 Li4 SiP4 and a 3D network in Ba4 Li16 Si3 P12.
• NMR confirmed crystal structures, with 7Li NMR suggesting potential mobility.
• Electrochemical impedance revealed low lithium-ion conductivities for these compounds.

Conclusions:

• The synthesized phosphidosilicates possess unique structural architectures.
• Despite structural features suggesting possible Li+ mobility, their ionic conductivity is low.
• These findings provide insights into the design principles for phosphidosilicate materials.