Indium(III) phosphate
| Names | |
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| Other names
Indium orthophosphate | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| InPO4 | |
| Molar mass | 209.79 g/mol |
| Appearance | White solid |
| Density | 4.9 g/cm3 |
| Practically insoluble in water | |
| Structure | |
| Orthorhombic | |
| Cmcm, No. 63 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Indium(III) phosphate is an inorganic compound of indium and phosphate with the chemical formula InPO4. It is a white solid that is practically insoluble in water.
Preparation
[edit]Indium(III) phosphate can be prepared by precipitation from solutions containing In3+ and phosphate ions. For example, indium(III) chloride reacts with phosphoric acid to form InPO4:[1]
- InCl3 + H3PO4 → InPO4↓ + 3 HCl
More generally, soluble indium salts form precipitates of indium phosphate when treated with acidic or neutral soluble phosphates in neutral or weakly acidic solution.[2]
Hydrated phases can be prepared hydrothermally. A monoclinic dihydrate, InPO4·2H2O, has been obtained from indium(III) hydroxide and phosphoric acid in the presence of hydrofluoric acid and quinuclidine.[3]
Structure and properties
[edit]At ambient pressure, anhydrous InPO4 crystallizes in the orthorhombic crystal system in space group Cmcm. Its structure is of the CrVO4 type: In3+ is six-coordinate in InO6 octahedra, while phosphorus is tetrahedrally coordinated in PO4 groups.[1]
At pressures above about 12 GPa, InPO4 undergoes a structural transformation. High-pressure diffraction studies indicate coexistence of tetragonal zircon-type (I41/amd) and scheelite-type (I41/a) phases together with the ambient orthorhombic phase. In the high-pressure phases, indium becomes eight-coordinate while phosphorus remains four-coordinate.[1]
Several hydrates are known. InPO4·H2O crystallizes in the triclinic crystal system, space group P1, with lattice parameters a = 5.4342 Å, b = 5.5508 Å, c = 6.5446 Å, α = 97.593°, β = 94.558° and γ = 107.565°.[4] Its three-dimensional framework contains In2O8(H2O)2 dimers linked by PO4 tetrahedra.
On heating between about 370 and 480 °C, the monohydrate loses its coordinated water to form anhydrous InPO4. This dehydration corresponds structurally to condensation of the hydrated indium dimers into chains of edge-sharing InO6 octahedra.[4]
The dihydrate InPO4·2H2O is also polymorphic. A monoclinic form with space group P21/n is isostructural with metavariscite-type AlPO4·2H2O, and an orthorhombic form with space group Pbca is also known.[3]
Applications
[edit]Indium phosphate has been investigated for use in electronic and optoelectronic materials. Its pressure-induced structural changes and the associated changes in indium coordination are of interest for understanding the behaviour of phosphate materials under extreme conditions.[1]
References
[edit]- 1 2 3 4 Dwivedi, Abhilash; Kaiwart, Rahul; Varma, Meera; Velaga, Srihari; Poswal, H. K. (2020). "High-pressure structural investigations on InPO4". Journal of Solid State Chemistry. 282 121065. doi:10.1016/j.jssc.2019.121065.
- ↑ Brukl, Alfred (2013). Elemente der dritten Hauptgruppe Teil II und der dritten Nebengruppe. Springer. p. 62.
- 1 2 Sugiyama, Kazumasa; Yu, Jihong; Hiraga, Kenji; Terasaki, Osamu (1999). "Monoclinic InPO4·2H2O". Acta Crystallographica Section C. 55 (3): 279–281. doi:10.1107/S010827019801292X.
- 1 2 Tang, Xuejiao; Lachgar, Abdessadek (1998). "The Missing Link: Synthesis, Crystal Structure, and Thermogravimetric Studies of InPO4·H2O". Inorganic Chemistry. 37 (24): 6181–6185. doi:10.1021/ic980548v.
