Chemistry:Pyrosilicate
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| Names | |
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| IUPAC name
Pyrosilicate
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| Other names
disilicate, diorthosilicate
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| Identifiers | |
3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| 326578 | |
PubChem CID
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| Properties | |
| O7Si2−6 | |
| Molar mass | 168.166 g·mol−1 |
| Conjugate acid | Pyrosilicic acid |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
 (what is   ?)
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| Infobox references | |
A pyrosilicate is a type of chemical compound; either an ionic compound that contains the pyrosilicate anion Si2O6−7, or an organic compound with the hexavalent ≡O3Si-O-SiO3≡ group. The anion is also called disilicate[1] or diorthosilicate.
Ionic pyrosilicates can be considered salts of the unstable pyrosilicic acid, H6Si2O7. Unlike the acid, the salts can be stable. Indeed, pyrosilicates occur widely in nature as a class of silicate minerals, specifically the sorosilicates.
Some notable synthetic pyrosilicates include
- sodium pyrosilicate Na6Si2O7, a possible component of water glass.
- sodium iron(II) pyrosilicate Na2Fe2Si2O7, a potential cathode material for batteries.[2]
- sodium manganese(II) pyrosilicate Na2Mn2Si2O7, another potential cathode material.[3][4]
Structure
The pyrosilicate anion can be described as two SiO4 tetrahedra that share a vertex (an oxygen atom). The vertices that are not shared carry a negative charge each.
The structure of solid sodium pyrosilicate was described by Volker Kahlenberg and others in 2010.[5]
Yuri Smolin and Yuri Shepelev determined in 1970 the crystal structures of pyrosilicates of rare earth elements with generic formula Ln2Si2O7, where "Ln" stands for either one of lanthanum, cerium, neodymium, samarium, europium, gadolinium, dysprosium, holmium, yttrium, erbium, thulium, or ytterbium. They were found to belong to four distinct crystallographic classes, determined by the size of the cation.[6] Other researchers also studied yttrium pyrosilicate Y2Si2O7.,[7][8] gadolinium pyrosilicate Gd2Si2O7.,[8] and scandium pyrosilicate Sc2Si2O7.[7]
Preparation
Rare earth pyrosilicates Ln2Si2O7 can be obtained by fusing the corresponding oxide Ln2O3 with silica in 1:2 molar ratio,[6] Single crystals can be grown by the Verneuil process[6] or the Czochralski method.[7]
References
- ↑ "Disilicate". Chemspider website, CSID:5257009, Accessed 2018-05-26
- ↑ Abhishek Panigrahi, Shin-ichi Nishimura, Tatau Shimada, Eriko Watanabe, Wenwen Zhao, Gosuke Oyama, and Atsuo Yamada (2017): "Sodium Iron(II) Pyrosilicate Na2Fe2Si2O7: A Potential Cathode Material in the Na2O-FeO-SiO2 System". Chemistry of Materials, volume 29, issue 10, pages 4361–4366. doi:10.1021/acs.chemmater.7b00764
- ↑ Viktor Renman, Mario Valvo, Cheuk-Wai Tai, and Cesar Pay Gómez (2017): "Manganese Pyrosilicates as Novel Positive Electrode Materials for Na-Ion Batteries". Uppsala University Publications, DIVA urn:nbn:se:uu:diva-334063
- ↑ Viktor Renman (2017): "Structural and Electrochemical Relations in Electrode Materials for Rechargeable Batteries", Doctoral Thesis, Uppsala University, Department of Chemistry. ORCID: 0000-0001-8739-4054
- ↑ Volker Kahlenberg, Thomas Langreiter, and Erik Arroyabe (2010): "Na6Si2O7 – The Missing Structural Link among Alkali Pyrosilicates". Zeitschrift für anorganishe und allgemeine Chemie (Journal for Inorganic and General Chemistry), volume 636, issue 11, pages 1974-1979. doi:10.1002/zaac.201000120
- ↑ 6.0 6.1 6.2 Yu. I. Smolin and Yu. F. Shepelev (1970): "The crystal structures of the rare earth pyrosilicates". Acta Crystallographica Section B, volume B26, pages 484-492. doi:10.1107/S0567740870002698
- ↑ 7.0 7.1 7.2 Anan'eva, G.V.; Karapetyan, V.E.; Korovkin, A.M.; Merkulyaeva, T.I.; Peschanskaya, I.A.; Savinova, I.P.; and Feofilov, P.P. (1982): "Strukturnye kharakteristiki i fizicheskie svojstva kristallov diorto(piro)silikatov lantanoidov, ittriya i skandiya, vyrashchennykh metodom Chokhral'skogo" ("Structural characteristics and physical properties of diortho(pyro)silicate crystals of lanthanides yttrium and scandium grown by the Czochralski technique"). Izv. Akad. Nauk SSSR, Neorg. Mater (translated in Inorganic Materials, USA) volume 18, issue 3, pages 442-445. ISSN 0002-337X.
- ↑ 8.0 8.1 Dias, H.W.; Glasser, F.P.; Gunwardane, R.P.; and Howie, R.A. (1990): "The crystal structure of δ-yttrium pyrosilicate, δ-Y2Si2O7". Zeitschrift für Kristallographie, volume 191, issues 1/2, pages 117-123; ISSN 0044-2968
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