View source for Silver molybdate

{{Overly detailed|section=|details=|date=August 2020}}{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 464391198
| Name = Silver molybdate
| ImageFile = 
<!-- | ImageSize = 200px -->
| OtherNames =
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10801079
| PubChem = 16217378
| InChI = 1/2Ag.Mo.4O/q2*+1;;;;2*-1/r2Ag.MoO4/c;;2-1(3,4)5/q2*+1;-2
| InChIKey = ^@€×,&#+=+÷×¥× ndnzjsnssi-QWQXGURBAC
| SMILES = [Ag+].[Ag+].[O-][Mo]([O-])(=O)=O
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/2Ag.Mo.4O/q2*+1;;;;2*-1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = MHLYOTJKDAAHGI-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|changed|??}}
| CASNo = 13765-74-7
}}
| Section2 = {{Chembox Properties
| Formula = Ag<sub>2</sub>MoO<sub>4</sub>
| MolarMass = 375.67 g/mol
| Appearance = yellow crystals
| Density = 6.18 g/cm<sup>3</sup>, solid
| Solubility = slightly soluble
| MeltingPtC = 483
| BoilingPt =
}}
| Section3 = {{Chembox Structure
| CrystalStruct = cubic
}}
}}
'''Silver molybdate''' (Ag<sub>2</sub>MoO<sub>4</sub>), a [[chemical compound]], is a yellow, cubic crystalline substance often used in glass. Its crystals present two types of electronic structure, depending on the pressure conditions to which the crystal is subjected.<ref name=":0">{{Cite journal|title = Behavior of silver molybdate at high-pressure|journal = Journal of Solid State Chemistry|date = 2012-12-01|pages = 391–397|volume = 196|doi = 10.1016/j.jssc.2012.07.003|first1 = A. K.|last1 = Arora|first2 = R.|last2 = Nithya|first3 = Sunasira|last3 = Misra|first4 = Takehiko|last4 = Yagi|bibcode = 2012JSSCh.196..391A}}</ref> At room temperature, Ag<sub>2</sub>MoO<sub>4</sub> exhibits a [[Spinel group|spinel-type]] cubic structure, known as β-Ag<sub>2</sub>MoO<sub>4</sub>, which is more stable in nature. However, when exposed to high hydrostatic pressure, the tetragonal α-Ag<sub>2</sub>MoO<sub>4</sub> forms as a [[Metastability|metastable]] phase.<ref name=":1">{{Cite journal|title = First-Principles Study of Pressure-Induced Phase Transitions and Electronic Properties of Ag2MoO4|journal = The Journal of Physical Chemistry C|date = 2014-02-20|issn = 1932-7447|pages = 3724–3732|volume = 118|issue = 7|doi = 10.1021/jp4118024|first1 = Armando|last1 = Beltrán|first2 = Lourdes|last2 = Gracia|first3 = Elson|last3 = Longo|first4 = Juan|last4 = Andrés}}</ref>

== Synthesis and properties ==
Research published in 2015<ref name=":2">{{Cite journal|title = Uncovering Metastable α-Ag2MoO4 Phase Under Ambient Conditions. Overcoming High Pressures by 2,3-Bis(2-pyridyl)pyrazine Doping|journal = Crystal Growth & Design|date = 2015-06-03|issn = 1528-7483|pages = 3032–3037|volume = 15|issue = 6|doi = 10.1021/acs.cgd.5b00455|first1 = Choon Hwee Bernard|last1 = Ng|first2 = Wai Yip|last2 = Fan}}</ref> reported the formation of α-Ag<sub>2</sub>MoO<sub>4</sub> by solution-phase precipitation under ambient conditions, using 3-bis(2-pyridyl)pyrazine (dpp) as a [[doping agent]]. The influence of the pH of the starting solution on the growth and formation processes of distinct heterostructures (brooms, flowers and rods) was investigated by Singh ''et al''.<ref name=":3">{{Cite journal|title = Broom-like and flower-like heterostructures of silver molybdate through pH controlled self assembly|journal = Journal of Nanoparticle Research|date = 2012-03-09|issn = 1388-0764|pages = 781|volume = 14|issue = 4|doi = 10.1007/s11051-012-0781-0|first1 = D. P.|last1 = Singh|first2 = B.|last2 = Sirota|first3 = S.|last3 = Talpatra|first4 = P.|last4 = Kohli|first5 = C.|last5 = Rebholz|first6 = S. M.|last6 = Aouadi|bibcode = 2012JNR....14..781S|hdl = 10533/128243|s2cid = 96310636|hdl-access = free}}</ref> and Fodjo ''et al''.,<ref name=":4">{{Cite journal|title = Low temperature synthesis and SERS application of silver molybdenum oxides|journal = Journal of Materials Chemistry A|volume = 1|issue = 7|pages = 2558–2566|doi = 10.1039/c2ta01018f|first1 = Essy Kouadio|last1 = Fodjo|first2 = Da-Wei|last2 = Li|first3 = Niamien Paulin|last3 = Marius|first4 = Trokourey|last4 = Albert|first5 = Yi-Tao|last5 = Long|date = 2013-01-23}}</ref> in which [[sodium borohydride]] was employed to induce the reduction of [[silver nanoparticle]]s on the surface of Ag<sub>2</sub>MoO<sub>4</sub> crystals in order to enhance [[Raman scattering]]. In other studies, Ag-Ag<sub>2</sub>MoO<sub>4</sub> composites prepared by microwave-assisted hydrothermal synthesis presented interesting photocatalytic activity for the degradation of [[rhodamine B]] under visible light.<ref>{{Cite journal|title = Microwave-assisted hydrothermal synthesis of cube-like Ag-Ag2MoO4 with visible-light photocatalytic activity|journal = Science China Chemistry|date = 2013-02-22|issn = 1674-7291|pages = 443–450|volume = 56|issue = 4|doi = 10.1007/s11426-013-4845-5|first1 = ZhaoQian|last1 = Li|first2 = XueTai|last2 = Chen|first3 = Zi-Ling|last3 = Xue|s2cid = 100948033}}</ref> In addition, Ag<sub>2</sub>MoO<sub>4</sub> mixed with [[graphite]] acts as a good lubricant for Ni-based composites, improving the [[Tribology|tribological]] properties of this system.<ref>{{Cite journal|title = Friction and Wear Behaviors of Ni-based Composites Containing Graphite/Ag2MoO4 Lubricants|journal = Tribology Letters|date = 2013-03-24|issn = 1023-8883|pages = 313–322|volume = 50|issue = 3|doi = 10.1007/s11249-013-0131-0|first1 = Eryong|last1 = Liu|first2 = Yimin|last2 = Gao|first3 = Junhong|last3 = Jia|first4 = Yaping|last4 = Bai|s2cid = 137297325}}</ref> Different synthetic methods have been employed to obtain pure β-Ag<sub>2</sub>MoO<sub>4</sub> crystals, including solid-state reaction or oxide mixture at high temperature,<ref>{{Cite journal|title = Molecular structural analysis of 55mol% CuI-45mol% Ag2MoO4 solid electrolyte using XPS and laser raman techniques|journal = Ionics|date = 2004-05-01|issn = 0947-7047|pages = 254–257|volume = 10|issue = 3–4|doi = 10.1007/BF02382825|first1 = S. Austin|last1 = Suthanthiraraj|first2 = Y. Daniel|last2 = Premchand|s2cid = 95974644}}</ref> melt-quenching,<ref>{{Cite journal|title = XANES and EXAFS at Mo K-edge in (AgI)1−x(Ag2MoO4)x glasses and crystals|journal = Solid State Ionics|date = 1999-06-01|pages = 189–192|volume = 121|issue = 1–4|doi = 10.1016/S0167-2738(98)00546-3|first1 = F|last1 = Rocca|first2 = A|last2 = Kuzmin|first3 = P|last3 = Mustarelli|first4 = C|last4 = Tomasi|first5 = A|last5 = Magistris}}</ref> and Czochralski growth.<ref>{{Cite journal|title = The growth of single crystals of lead molybdate by the Czochralski technique|journal = Materials Science and Engineering: A|date = 1993-12-20|pages = 23–27|volume = 173|issue = 1–2|doi = 10.1016/0921-5093(93)90179-I|first1 = Stephen|last1 = Brown|first2 = Alison|last2 = Marshall|first3 = Philip|last3 = Hirst}}</ref> 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-Ag<sub>2</sub>MoO<sub>4</sub> crystals have been synthesized by [[Coprecipitation|co-precipitation]],{{Citation needed|date=December 2019|reason=removed citation to predatory publisher content}} [[Microwave chemistry|microwave-assisted]] hydrothermal synthesis,<ref>{{Cite journal|title = Experimental and Theoretical Investigations of Electronic Structure and Photoluminescence Properties of β-Ag2MoO4 Microcrystals|journal = Inorganic Chemistry|date = 2014-06-02|issn = 0020-1669|pages = 5589–5599|volume = 53|issue = 11|doi = 10.1021/ic500335x|pmid = 24840935|first1 = A. F.|last1 = Gouveia|first2 = J. C.|last2 = Sczancoski|first3 = M. M.|last3 = Ferrer|first4 = A. S.|last4 = Lima|first5 = M. R. M. C.|last5 = Santos|first6 = M. Siu|last6 = Li|first7 = R. S.|last7 = Santos|first8 = E.|last8 = Longo|first9 = L. S.|last9 = Cavalcante|url = http://www.producao.usp.br/handle/BDPI/50833}}</ref> a dynamic template route using polymerization of [[acrylamide]] assisted templates,<ref>{{Cite journal|last1=Jiang|first1=Hao|last2=Liu|first2=Jin-Ku|last3=Wang|first3=Jian-Dong|last4=Lu|first4=Yi|last5=Yang|first5=Xiao-Hong|date=2015-07-14|title=Thermal perturbation nucleation and growth of silver molybdate nanoclusters by a dynamic template route|journal=CrystEngComm|volume=17|issue=29|pages=5511–5521|doi=10.1039/c5ce00039d}}</ref> and an impregnation/[[calcination]] method.<ref>{{Cite journal|title = Co-benefit of Ag and Mo for the catalytic oxidation of elemental mercury|journal = Fuel|date = 2015-10-15|pages = 891–897|volume = 158|doi = 10.1016/j.fuel.2015.05.034|first1 = Songjian|last1 = Zhao|first2 = Zhen|last2 = Li|first3 = Zan|last3 = Qu|first4 = Naiqiang|last4 = Yan|first5 = Wenjun|last5 = Huang|first6 = Wanmiao|last6 = Chen|first7 = Haomiao|last7 = Xu}}</ref>

In 2015, the literature reported the formation of β-Ag<sub>2</sub>MoO<sub>4</sub> crystals using different chemical solvents in the reaction medium. These β-Ag<sub>2</sub>MoO<sub>4</sub> microcrystals were synthesized by the precipitation method, employing several [[Polar solvent|polar solvents]]: [[Purified water|deionized water]] (H<sub>2</sub>O), [[methanol]] (CH<sub>4</sub>O), [[ethanol]] (C<sub>2</sub>H<sub>6</sub>O), [[1-Propanol|1-propanol]] (C<sub>3</sub>H<sub>8</sub>O) and [[N-Butanol|1-butanol]] (C<sub>4</sub>H<sub>10</sub>O) at 60 °C for 8 h. [[X-ray diffraction]] (XRD), [[Rietveld refinement|Rietveld refinements]] and field emission scanning electron microscopy ([[FESEM]]) were employed in structural and morphological characterizations.<ref>{{Cite journal|title = Structural, morphological and optical investigation of β-Ag 2 MoO 4 microcrystals obtained with different polar solvents|journal = CrystEngComm|volume = 17|issue = 43|pages = 8207–8211|doi = 10.1039/c5ce01662b |first1 = F. S.|last1 = Cunha|first2 = J. C.|last2 = Sczancoski|first3 = I. C.|last3 = Nogueira|first4 = V. G. de|last4 = Oliveira|first5 = S. M. C.|last5 = Lustosa|first6 = E.|last6 = Longo|first7 = L. S.|last7 = Cavalcante|date = 2015-10-28}}</ref> Moreover, some researchers have investigated new ways to improve the photocatalytic properties of β–Ag<sub>2</sub>MoO<sub>4</sub> crystals through hydrothermal processing at different temperatures (100, 120, 140 and 160 °C) for 2 h and replacement of Ag atoms by Zn to formation of silver zinc molybdate [β–(Ag<sub>2−2x</sub>Znx)MoO<sub>4</sub>] microcrystals by a sonochemical method at 30 °C for 3 h. These new crystals were able to degrade the organic cationic dye rhodamine B<ref name="Sousa">{{cite journal |last1=Sousa|first1=Giancarlo da Silva |last2=Nobre|first2=Francisco Xavier |last3=Júnior|first3=Edgar lves Araújo |last4=Sambrano|first4=Julio Ricardo |last5=Albuquerque|first5=Anderson dos Reis |last6=Bindá|first6=Rosane dos Santos |last7=Couceiro|first7=Paulo Rogério da Costa |last8=Brito|first8=Walter Ricardo |last9=Cavalcante|first9=Laecio Santos |date=20 July 2018 |title=Hydrothermal synthesis, structural characterization and photocatalytic properties of β--Ag2MoO4 microcrystals: Correlation between experimental and theoretical data |journal=Arabian Journal of Chemistry |doi=10.1016/j.arabjc.2018.07.011 |last10=Santos|first10=Maria Rita Morais|last11=Matos|first11=Jose Milton Elias|volume=13 |pages=2806–2825 |doi-access=free}}</ref> and the anionic dye Remazol Brilliant Violet 5R<ref name="[17]">{{cite journal |last1=Coimbra |first1=D.W. |last2=Cunha |first2=F.S. |last3=Sczancoski |first3=J.C. |last4=de Carvalho |first4=J.F.S. |last5=de Macêdo |first5=F.R.C. |last6=Cavalcante |first6=L.S. |title=Structural refinement, morphology and photocatalytic properties of β-(Ag<sub>2−2''x''</sub>Zn<sub>x</sub>)MoO<sub>4</sub> microcrystals synthesized by the sonochemical method |journal=Journal of Materials Science: Materials in Electronics |volume=30 |issue=2 |pages=1322–1344 |date=2019 |doi=10.1007/s10854-018-0401-6|s2cid=139865569 }}</ref>

==References==
{{reflist}}

{{Silver compounds}}
{{Molybdates}}

[[Category:Silver compounds]]
[[Category:Molybdates]]