Silver(I) selenide

Silver(I) selenide
Names
	Other names Naumannite
Identifiers
CAS Number	1302-09-6 ;
ECHA InfoCard	100.013.727
PubChem CID	6914520;
Properties
Chemical formula	Ag2Se
Molar mass	294.7 g/mol
Density	8.216 g/cm3, solid
Melting point	896.85 °C (1,646.33 °F; 1,170.00 K)
Solubility in water	insoluble
Band gap	0.15 eV [1]
Structure
Crystal structure	orthorhombic, oP12
Space group	P212121, No. 19
	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 selenide (Ag₂Se) is the reaction product formed when selenium toning analog silver gelatine photo papers in photographic print toning. The selenium toner contains sodium selenite (Na₂SeO₃) as one of its active ingredients, which is the source of the selenide (Se²⁻) anion combining with the silver in the toning process.

It is found in nature as the mineral naumannite, a comparatively rare silver mineral which has nevertheless become recognized as important silver compound in some low-sulfur silver ores from mines in Nevada and Idaho.^[2]^[3]

Structure

Silver selenide normally exists in the orthorhombic β-phase but at temperatures above 130 °C transforms into the cubic α-Ag₂Se (Space group Im-3m, No. 229, Pearson symbol cI20). The phase transition increases ionic conductivity by 10,000 times to about 2 S/cm ^[4]

References

↑ O. Madelung (2004). Semiconductors: data handbook. Birkhäuser. p. 461. ISBN 3-540-40488-0.
↑ http://nevada-outback-gems.com/Reference_pages/sulfide_ores.htm Notes on naumannite.
↑ Guilbert, John M.; Park Jr, Charles F. (2007-02-09). The Geology of Ore Deposits. Waveland Press. p. 557. ISBN 978-1-4786-0887-5.
↑ Kirchhoff F.; Holender J.M.; Gillan M.J. (1996). "Structure, dynamics, and electronic structure of liquid Ag-Se alloys investigated by ab initio simulation". Physical Review B. 54: 190–202. arXiv:mtrl-th/9602001. Bibcode:1996PhRvB..54..190K. doi:10.1103/PhysRevB.54.190.

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[r1-1] O. Madelung (2004). Semiconductors: data handbook. Birkhäuser. p. 461. ISBN 3-540-40488-0.

[2] ttp://nevada-outback-gems.com/Reference_pages/sulfide_ores.htm Notes on naumannite.

[3] Guilbert, John M.; Park Jr, Charles F. (2007-02-09). The Geology of Ore Deposits. Waveland Press. p. 557. ISBN 978-1-4786-0887-5.

[4] Kirchhoff F.; Holender J.M.; Gillan M.J. (1996). "Structure, dynamics, and electronic structure of liquid Ag-Se alloys investigated by ab initio simulation". Physical Review B. 54: 190–202. arXiv:mtrl-th/9602001. Bibcode:1996PhRvB..54..190K. doi:10.1103/PhysRevB.54.190.