Optical anisotropy in Mo-Te-O frameworks constructed from distorted MoO₆ and TeO₃ units

Area of Science:

• Materials Science
• Solid-State Chemistry
• Inorganic Chemistry

Background:

• Molybdenum-tellurium-oxide (Mo-Te-O) systems offer potential for novel material properties.
• Understanding structure-property relationships in oxides is crucial for materials design.

Purpose of the Study:

• Synthesize and structurally characterize new Mo-Te-O compounds.
• Investigate the optical anisotropy of these novel materials.
• Elucidate the relationship between crystal structure and optical properties.

Main Methods:

• Synthesis of (NH4)2MgMo4Te2O18 and β-MoTe2O7.
• Structural characterization using X-ray diffraction and microscopy.
• Optical anisotropy measurements using polarized optical microscopy.
• Theoretical calculations using density functional theory (DFT).

Main Results:

• Two new Mo-Te-O compounds were successfully synthesized and characterized.
• Both compounds exhibit moderate birefringence due to distorted MoO6 octahedra and TeO3 trigonal pyramids.
• DFT calculations confirmed the observed optical anisotropy, linked to Mo-O-Te connectivity and framework dimensionality.
• (NH4)2MgMo4Te2O18 displays unique surface coloration, suggesting electronic effects.

Conclusions:

• The study successfully synthesized and characterized two new Mo-Te-O compounds.
• Structural features, including cooperative distortions and framework connectivity, govern optical anisotropy.
• These findings contribute to the understanding of optical properties in Mo-Te-O oxides.