Ag₂Mo₂O₇: an oxide solid-state Ag⁺ electrolyte.

Area of Science:

• Solid-state chemistry and materials science.
• Inorganic synthesis and characterization.
• Energy storage materials research.

Background:

• Development of novel electrolytes is crucial for advancing electrochemical energy storage devices.
• Silver-based compounds are explored for their ionic conductivity properties.
• Understanding material properties like band gap and vibrational modes is key to optimizing performance.

Purpose of the Study:

• To synthesize and characterize silver dimolybdate (Ag₂Mo₂O₇) powders and micro-crystals.
• To investigate the structural, electronic, vibrational, and ionic conductivity properties of Ag₂Mo₂O₇.
• To evaluate Ag₂Mo₂O₇ as a potential silver oxide ion electrolyte.

Main Methods:

• Solid-state reactions at 400 °C and 500 °C for synthesis.
• Rietveld refinements for crystal structure determination (triclinic, P1̄).
• Reflectance measurements and Density Functional Theory (DFT) calculations for band gap analysis.
• DFT and Raman spectroscopy for vibrational mode investigation.
• Impedance analysis for ionic conductivity and activation energy determination.

Main Results:

• Ag₂Mo₂O₇ synthesized with homogeneous powder (2-8 μm) and good sintering (∼93% relative density).
• Crystal structure determined as triclinic (P1̄) with specific cell parameters.
• Indirect band gaps determined as 2.63 eV (experimental) and 1.80 eV (DFT).
• 24 out of 33 predicted Raman modes were experimentally observed.
• Valence bands composed of O-2p and Ag-4d; conduction bands of Mo-4d and O-2p orbitals.
• Silver oxide ion electrolyte conductivity of ∼5 × 10⁻⁴ S cm⁻¹ at 450 °C.
• Carrier activation energy determined as 0.88(3) eV.

Conclusions:

• Ag₂Mo₂O₇ is successfully synthesized and structurally characterized.
• The material exhibits properties consistent with a silver oxide ion electrolyte.
• The determined conductivity and electronic structure suggest potential for energy storage applications.