LiMo₈O₁₀: Polar Crystal Structure with Infinite Edge-Sharing Molybdenum Octahedra

Area of Science:

• Solid-state chemistry
• Materials science
• Crystallography

Background:

• Lithium molybdenum oxides are of interest for their diverse structural and electronic properties.
• Understanding the relationship between crystal structure and physical properties is crucial for materials design.

Purpose of the Study:

• To synthesize and characterize polycrystalline LiMo8O10.
• To investigate its crystal structure, electronic, magnetic, and thermal properties.

Main Methods:

• High-temperature solid-state synthesis.
• Powder neutron diffraction and solid-state NMR for structural analysis.
• X-ray absorption near-edge spectroscopy (XAS) for valence determination.
• Magnetic susceptibility, resistivity, and heat capacity measurements.

Main Results:

• LiMo8O10 was synthesized with a polar tetragonal structure (I41md) featuring infinite Mo-O chains with Mo-Mo bonding.
• The material is paramagnetic down to 1.8 K and exhibits semiconducting behavior.
• Resistivity follows Mott's variable range hopping (VRH) model between 215 and 45 K, with a sharp increase below 5 K.
• Negative magnetoresistance was observed between 2 and 25 K.
• Debye temperature was determined to be 365 K.

Conclusions:

• The synthesis and characterization confirm the polar tetragonal structure of LiMo8O10.
• The material displays semiconducting behavior governed by VRH and exhibits negative magnetoresistance, suggesting potential for electronic applications.
• The strong Mo-Mo bonding within the Mo-O chains influences its electronic properties.