RE₃Mo₁₄O₃₀ and RE₂Mo₉O₁₉, Two Reduced Rare-Earth Molybdates with Honeycomb-Related Structures ( RE = La-Pr)

Area of Science:

• Solid State Chemistry
• Inorganic Materials Science
• Rare-Earth Chemistry

Background:

• Rare-earth molybdenum oxides are a class of materials with diverse structural and electronic properties.
• Understanding the synthesis and structure-property relationships of novel phases is crucial for materials discovery.

Purpose of the Study:

• To synthesize and characterize previously unreported rare-earth molybdenum oxide phases.
• To investigate the structural, magnetic, and electrical properties of these new materials.

Main Methods:

• High-temperature synthesis using halide fluxes under vacuum.
• Single-crystal X-ray diffraction for structural determination.
• Magnetic susceptibility and electrical resistivity measurements.

Main Results:

• Two new phases, RE3Mo14O30 and RE2Mo9O19, were successfully synthesized.
• Both phases crystallize in the triclinic P1̅ space group with layered structures featuring MoO6 octahedra and vacancies.
• Unique Mo-Mo bonding arrangements, including dimers, tetramers, pentamers, and hexamers, were observed.
• RE2Mo9O19 phases exhibit paramagnetic behavior, while La3Mo14O30 orders antiferromagnetically at 18 K.
• All synthesized samples demonstrated nondegenerate semiconducting behavior.

Conclusions:

• The synthesis of novel RE3Mo14O30 and RE2Mo9O19 phases expands the known rare-earth molybdenum oxide family.
• The intricate layered structures and diverse Mo-Mo bonding influence the observed magnetic and electrical properties.
• These materials represent promising candidates for further investigation in solid-state chemistry and materials science.