Zinc selenide

Zinc selenide
Zinc selenide
Zinc selenide
Names
Other names
Zinc selenide
Stilleite
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.873 Edit this at Wikidata
EC Number
  • 215-259-7
UNII
  • InChI=1S/Se.Zn
    Key: SBIBMFFZSBJNJF-UHFFFAOYSA-N
  • zincblende structure: [SeH+2]12[ZnH2-2][SeH+2]3[ZnH2-2][SeH+2]([ZnH-2]14)[ZnH-2]1[Se+2]5([ZnH-2]38)[Zn-2]26[SeH+2]2[ZnH-2]([Se+2]4)[SeH+2]1[ZnH2-2][SeH+2]3[ZnH-2]2[Se+2][ZnH-2]([SeH+2]6[ZnH-2]([SeH+2])[SeH+2]68)[SeH+2]([ZnH2-2]6)[ZnH-2]35
  • wurtzite structure: [ZnH2-2]1[Se+2]47[ZnH-2]2[Se+2][ZnH-2]3[Se+2]8([ZnH2-2][SeH+2]([ZnH2-2]4)[ZnH2-2]6)[ZnH-2]4[Se+2][ZnH-2]5[Se+2]6([ZnH2-2]6)[Zn-2]78[Se+2]78[ZnH-2]([SeH+2]69)[SeH+2]5[ZnH2-2][SeH+2]4[ZnH-2]7[SeH+2]3[ZnH2-2][SeH+2]2[ZnH-2]8[SeH+2]1[ZnH2-2]9
  • wurtzite structure: [ZnH2-2]1[SeH+2]([ZnH2-2]6)[ZnH2-2][SeH+2]7[ZnH-2]2[Se+2][Zn-2]3([Se+2][ZnH-2]9[Se+2]5)[Se+2]18[Zn-2]45[Se+2][ZnH-2]5[SeH+2]6[Zn-2]78[Se+2]78[ZnH2-2][SeH+2]5[ZnH2-2][Se+2]4([ZnH2-2][SeH+2]9[ZnH2-2]4)[ZnH-2]7[Se+2]34[ZnH2-2][SeH+2]2[ZnH2-2]8
Properties
ZnSe
Molar mass 144.35 g/mol
Appearance light yellow solid
Density 5.27 g/cm3
Melting point 1,525 °C (2,777 °F)
negligible
Band gap 2.82 eV (10 K)
2.67 (550 nm)
2.40 (10.6 μm)
Structure
Zincblende (cubic)
a = 566.8 pm
Tetrahedral (Zn2+)
Tetrahedral (Se2−)
Thermochemistry
−177.6 kJ/mol
Hazards
GHS labelling:
GHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard
Danger
H301, H331, H373, H410
P260, P264, P270, P271, P273, P301+P310, P304+P340, P311, P314, P321, P330, P391, P403+P233, P405, P501
Related compounds
Other anions
 Zinc oxide
Zinc sulfide
Zinc telluride
Other cations
 Cadmium selenide
Mercury selenide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Zinc selenide is the inorganic compound with the formula ZnSe. It is a lemon-yellow solid although most samples have a duller color due to the effects of oxidation. It is an intrinsic semiconductor with a band gap of about 2.70 eV at 25 °C (77 °F), equivalent to a wavelength of 459 nm. ZnSe occurs as the rare mineral stilleite, named after Hans Stille.

Synthesis and properties

ZnSe is available in both hexagonal (wurtzite) and cubic (zincblende) polymorphs. In both cases, the Zn2+ and Se2− sites are tetrahedral. The difference in the structures related to close packing motifs, hexagonal vs cubic.

Cubic ZnSe is produced by treatment of an aqueous solution of zinc sulfate with hydrogen selenide:

ZnSO4 + H2Se → ZnSe + H2SO4

Heating the cubic form gives hexagonal ZnSe.

An alternative synthesis involves heating a mixture of zinc oxide, zinc sulfide, and selenium:

2 ZnO + ZnS + 3 Se → 3 ZnSe + SO2

It is a wide-bandgap semiconductor of the II-VI semiconductor group (since zinc and selenium belong to the 12th and 16th groups of the periodic table, respectively). The material can be n-type doped with, for instance, halogen elements. P-type doping is more difficult, but can be achieved by introducing gallium.

Similar to zinc sulfide, ZnSe is produced as microcrystalline sheets by synthesis from hydrogen selenide gas and zinc vapour. Another method of producing is a growth from melt under excessive pressure of inert gas (Ar usually).

It can be deposited as a thin film by chemical vapour deposition techniques including MOVPE and vacuum evaporation.

Reactions

ZnSe is insoluble in water, but dissolves in concentrated hydrochloric acid giving hydrogen selenide gas.

Zinc selenide can slowly react with atmospheric moisture if poorly polished - as it is gradually hydrolyzed by moisture giving the faint rotten garlicky odor of hydrogen selenide at trace amounts. This is not generally a serious problem. Except where optics are used in spectroscopy or at the Brewster angle, antireflection or beamsplitting optical coatings are generally employed.

Applications

Zinc selenide has a few commercial applications for its optical properties. Its wide transmission wavelength range (0.45 μm to 21.5 μm recommends it as an IR material (windows).). The refractive index is about 2.67 at 550 nm (green), and about 2.40 at 10.6 μm (LWIR).

Its luminescence properties have been well investigated.

ZnSe doped with chromium (ZnSe:Cr) is an infrared laser gain medium, emitting at about 2.4 μm.

ZnSe activated with tellurium (ZnSe(Te)) is a scintillator with emission peak at 640 nm, suitable for matching with photodiodes. It is used in x-ray and gamma ray detectors. ZnSe scintillators are significantly different from the ZnS ones.

References

  1. ↑ F. Wagenknecht; R. Juza (1963). "Zinc (II) Selenide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2pages=1078. NY, NY: Academic Press.
  2. ↑ "Institute for Single Crystals - Materials and Products - AIIBVI - Passive Laser Optics Elements". iscrystals.com. Archived from the original on 2016-12-28. Retrieved 2016-12-28.
  3. ↑ https://web.archive.org/web/20190422005411/http://www.kayelaby.npl.co.uk/general_physics/2_5/2_5_8.html Kaye and Laby online at NPL via archive.org
  4. ↑ Shen, Zhaoze; Wang, Qian; Cao, Kequan; Song, Xuerong; Yu, Binbin; Ning, Jiajia; Huang, Fei; Tian, Jianjun (2026). "Zinc chalcogenide semiconductor nanocrystals: From synthesis to optoelectronic applications". Chemical Society Reviews. 55 (13): 7107–7164. doi:10.1039/d5cs01317h. PMID 42300471.
  5. ↑ Cr2+ excitation levels in ZnSe and ZnS, G. Grebe, G. Roussos and H.-J. Schulz, J. Phys. C: Solid State Phys. vol. 9 pp. 4511-4516 (1976) doi:10.1088/0022-3719/9/24/020