Silver molybdate

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Silver molybdate, with the formula Ag2MoO4, is a yellow inorganic solid.

Structure and forms
- It crystallizes in a cubic system and can exist as two forms depending on conditions: beta-Ag2MoO4 (the common room-temperature form) and alpha-Ag2MoO4 (a metastable tetragonal form formed under high pressure).
- Alpha can be produced by solution-phase precipitation at room temperature using a dopant called 3-bis(2-pyridyl)pyrazine (dpp). The starting solution’s pH influences crystal shapes, creating broom-like, flower-like, or rod structures.

Synthesis (short overview)
- Beta form: solid-state reaction or oxide mixtures at high temperature, melt-quenching, or Czochralski growth.
- Alpha form: solution-phase precipitation with a dopant; other methods include co-precipitation, microwave-assisted hydrothermal synthesis, templated routes with polyacrylamide, and impregnation/calcination.
- Beta crystals can also be made through precipitation in polar solvents.

Properties
- Molar mass: 375.67 g/mol
- Density: 6.18 g/cm3
- Melting point: 483 °C
- Solubility: slightly soluble in water
- Appearance: yellow crystals

Uses
- Commonly used in glassmaking.

Photocatalysis and composites
- The beta form’s photocatalytic performance can be improved by hydrothermal treatment at different temperatures.
- Replacing some silver with zinc to form beta-(Ag2-2xZnx)MoO4 enhances dye degradation (e.g., rhodamine B and Remazol Brilliant Violet 5R).
- Ag-Ag2MoO4 composites made by microwave-assisted hydrothermal synthesis show visible-light activity for degrading rhodamine B.
- Mixing Ag2MoO4 with graphite can improve lubricating properties in nickel-based composites.

Related compounds
- Silver decamolybdate is a related compound.