Silver molybdate

Silver molybdate

Identifiers
CAS Number	13765-74-4 N
ChemSpider	10801079 Y
Jmol 3D model	Interactive image
PubChem	16217378
InChI InChI=1S/2Ag.Mo.4O/q2*+1;;;;2*-1 Y Key: MHLYOTJKDAAHGI-UHFFFAOYSA-N Y InChI=1/2Ag.Mo.4O/q2*+1;;;;2*-1/r2Ag.MoO4/c;;2-1(3,4)5/q2*+1;-2 Key: MHLYOTJKDAAHGI-QWQXGURBAC
SMILES [Ag+].[Ag+].[O-][Mo]([O-])(=O)=O
Properties
Chemical formula	Ag2MoO4
Molar mass	375.67 g/mol
Appearance	yellow crystals
Density	6.18 g/cm3, solid
Melting point	483 °C (901 °F; 756 K)
Solubility in water	slightly soluble
Structure
Crystal structure	cubic
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Silver molybdate (Ag₂MoO₄) presents two types of electronic structure, depending on the pressure conditions to which the crystal is subjected. At room temperature, Ag₂MoO₄ exhibits a spinel-type cubic structure related to beta (β-Ag₂MoO₄) phase, which is more stable in nature. However, when exposed to high hydrostatic pressure, these crystals have a tetragonal structure associated to alpha (α-Ag₂MoO₄) metastable phase. Recently, the literature has reported the formation of α-Ag2MoO4 metastable phase by the solution-phase precipitation method under environment condition, and using 3-bis(2-pyridyl)pyrazine (dpp) as doping. The influence of pH at starting solution on the growth and formation processes of distinct heterostructures (brooms, flowers and rods) was investigated by Singh et al. and Fodjo et al., in which the sodium borohydride was employed to induce the reduction of silver nanoparticles on the surface of Ag₂MoO₄ crystals in order to enhance the Raman scattering. In other studies, Ag-Ag₂MoO₄ composites prepared by microwave-assisted hydrothermal synthesis presented interesting photocatalytic activity for the degradation of Rhodamine B under visible light. In addition, Ag2MoO4 mixed with graphite acts as a good lubricant for Ni-based composites, improving the tribological properties of this system. Different synthesis methods have been employed to obtain pure β-Ag₂MoO₄ crystals, including solid-state reaction or oxide mixture at high temperature, melt-quenching and Czochralski growth. Particularly, high temperatures, long processing times, and/or sophisticated equipment are necessary in these synthetic routes. Moreover, the final products may be composed of irregular particle shapes with nonhomogeneous size distribution as well as contain the presence of secondary phases. In recent years, pure β-Ag2MoO4 crystals have been synthesized by the co-precipitation, microwave-assisted hydrothermal synthesis, dynamic template route using polymerization of the acrylamide assisted templates and impregnation/calcination method.

Recently, the literature have reported the formation of β-Ag₂MoO₄ crystals using different chemical solvents in the reaction medium. These β-Ag₂MoO₄ microcrystals were synthesized by the precipitation method, employing several polar solvents: deionized water (H₂O), methanol (CH₄O), ethanol (C₂H₆O), 1-propanol (C₃H₈O) and 1-butanol (C₄H₁₀O) at 60^oC for 8 h. X-ray diffraction (XRD), Rietveld refinements and field emission scanning electron microscopy (FESEM) were employed in structural and morphological characterizations.

A schematic representation of a β-Ag₂MoO₄ structure modeled by means of Rietveld refinement data is illustrated below:

https://photos.google.com/album/AF1QipMDxzPdU5M9hzKMkJEE-GDVYrDFnS50MHMPSAOe/photo/AF1QipMf9YfsTzQJtcP7YZLt4Ca1CFLzYgmFQjPWaot4?key=CMbW68ma-I-N_gE