Cadmium selenide: Difference between revisions

| verifiedrevid = 443493476

| ImageSize = 244

| ImageName = Ball and stick model of crystaline cadmium selenide

| ImageSize1 = 244

| ImageName1 = Sample of cadmium selenide in a vial

| IUPACName = Cadmium selenide{{Citation needed|date = August 2011}}

| SystematicName = Selanylidenecadmium<ref>{{Cite web|url = http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=14784|title = cadmium selenide - PubChem Public Chemical Database|work = The PubChem Project|location = USA|publisher = Nation Center for Biotechnology Information|at = Descriptors Computed from Structure}}</ref>

| OtherNames = Cadmium(2+) selenide<ref name = "cadmium selenide (CHEBI:50834)">{{Cite web|url = https://www.ebi.ac.uk/chebi/searchId.do?chebiId=50834|title = cadmium selenide (CHEBI:50834)|work = Chemical Entities of Biological Interest (ChEBI)|location = UK|publisher = European Bioinformatics Institute|at = IUPAC Names}}</ref><br />

Cadmium(II) selenide<ref name = "cadmium selenide (CHEBI:50834)" />

| Section1 = {{Chembox Identifiers

| CASNo = 1306-24-7

| CASNo_Ref = {{cascite|correct|CAS}}

| PubChem = 14784

| PubChem_Ref = {{Pubchemcite|correct|??}}

| ChemSpiderID = 14101

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| EINECS = 215-148-3

| UNNumber = 2570

| MeSHName = cadmium+selenide

| ChEBI = 50834

| ChEBI_Ref = {{ebicite|correct|EBI}}

| RTECS = EV2300000

| Gmelin = 13656

| SMILES = [Se]=[Cd]

| StdInChI = 1S/Cd.Se

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| InChI = 1/Cd.Se/rCdSe/c1-2

| StdInChIKey = AQCDIIAORKRFCD-UHFFFAOYSA-N

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| InChIKey = AQCDIIAORKRFCD-BBSQRNTLAE

| Section2 = {{Chembox Properties

| Cd = 1

| Se = 1

| ExactMass = 193.819879949 g mol^-1

| Appearance = Vivid, dark red, opaque crystals

| Density = 5.816 g cm^-3

| MeltingPtK = 1541

| BandGap = 1.74 eV

| RefractIndex = 2.5

| Section3 = {{Chembox Structure

| CrystalStruct = [[Wurtzite (crystal structure)|Wurtzite]]

| SpaceGroup = ''C''_6v⁴-''P''6₃''mc''

| Coordination = Tetrahedral

| Section4 = {{Chembox Hazards

| GHSPictograms = {{GHS skull and crossbones}} {{GHS health hazard}} {{GHS environment}}

| GHSSignalWord = '''DANGER'''

| HPhrases = {{H-phrases|301|312|331|373|410}}

| PPhrases = {{P-phrases|261|273|280|301+310|311|501}}

| EUIndex = 048-001-00-5

| EUClass = {{Hazchem T}} {{Hazchem N}}

| RPhrases = {{R21}}, {{R23/25}}, {{R33}}, {{R50/53}}

| SPhrases = {{S2}}, {{S36/37}}, {{S45}}, {{S60}}, {{S61}}

| Section5 = {{Chembox Related

| OtherAnions = [[Cadmium oxide]],<br/>[[Cadmium sulfide]],<br />[[Cadmium telluride]]

| OtherCations = [[Zinc selenide]],<br />[[Mercury(II) selenide]]

}}

'''Cadmium selenide''' ([[Cadmium|Cd]][[Selenium|Se]]) is a solid, binary compound of [[cadmium]] and [[selenium]]. Common names for this compound are '''cadmium(II) selenide''', '''cadmium selenide''', and '''cadmoselite''' (a very rare mineral).

Cadmium selenide is a [[semiconductor|semiconducting]] material, but has yet to find many applications in manufacturing. This material is transparent to infra-red (IR) light, and has seen limited use in windows for instruments utilizing IR light.

Much current research on cadmium selenide has focused on [[nanoparticle]]s. Researchers are concentrating on developing controlled syntheses of CdSe nanoparticles. In addition to synthesis, scientists are working to understand the properties of cadmium selenide, as well as apply these materials in useful ways.

Three crystalline forms of CdSe are known: [[Wurtzite (crystal structure)|wurtzite]] (hexagonal), [[Cubic_crystal_system#Zincblende_structure|sphalerite]] (cubic) and [[Cubic_crystal_system#Rock-salt_structure|rock-salt]] (cubic). The sphalerite CdSe structure is unstable and converts to the wurtzite form upon moderate heating. The transition starts at about 130 °C, and at 700 °C it completes within a day. The rock-salt structure is only observed under high pressure.<ref>{{cite book|page=202| url= http://books.google.com/?id=Ty5Ymlg_Mh0C&pg=PA202| title=Semiconductor materials|author= Lev Isaakovich Berger| publisher= CRC Press|year = 1996| isbn =0849389127}}</ref>

The production of cadmium selenide has been carried out in two different ways. The preparation of bulk crystalline CdSe is done by the High-Pressure Vertical Bridgman method or High-Pressure Vertical Zone Melting.<ref>[http://www.sttic.com.ru/lpcbc/Basics.html II-VI compound crystal growth, HPVB & HPVZM basics]</ref>

Cadmium selenide may also be produced in the form of [[nanoparticles]]. (see applications for explanation) Several methods for the production of CdSe nanoparticles have been developed: arrested precipitation in solution, synthesis in structured media, high temperature pyrolysis, sonochemical, and radiolytic methods are just a few.<ref name=didenko>{{cite journal|doi=10.1021/ja054124t|year=2005|month=Sep|author=Didenko, Yt; Suslick, Ks|title=Chemical aerosol flow synthesis of semiconductor nanoparticles.|volume=127|issue=35|pages=12196–7|issn=0002-7863|pmid=16131177|journal=Journal of the American Chemical Society}}</ref>

Production of cadmium selenide by arrested precipitation in solution is performed by introducing alkylcadmium and trioctylphosphine selenide (TOPSe) precursors into a heated solvent under controlled conditions.<ref>{{cite journal| doi=10.1021/ja00072a025| title=Synthesis and characterization of nearly monodisperse CdE (E = sulfur, selenium, tellurium) semiconductor nanocrystallites| year=1993| author=Murray, C. B.| journal=Journal of the American Chemical Society| volume=115| pages=8706| last2=Norris| first2=D. J.| last3=Bawendi| first3=M. G.}}</ref>

:Me₂Cd + TOPSe → CdSe + (byproducts).

==Applications==

[[File:CdSeqdots.jpg|thumb|left|A photograph and representative spectrum of [[photoluminescence]] from colloidal CdSe [[quantum dots]] excited by UV light.]]

Cadmium selenide in its [[Wurtzite (crystal structure)|wurtzite]] crystal structure is an important [[II-VI semiconductor]]. As a semiconductor CdSe is an n-type semiconductor, which is difficult to dope p-type, however p-type doping has been achieved using [[nitrogen]].<ref>{{cite journal|author=T Ohtsuka, J Kawamata, Z Zhu, T Yao|journal= Applied Physics Letters|volume= 65|page= 466|year=1994|doi=10.1063/1.112338|title=p-type CdSe grown by molecular beam epitaxy using a nitrogen plasma source}}</ref> CdSe is also being developed for use in opto-electronic devices, laser diodes, nanosensing, and biomedical imaging.<ref>{{cite journal|doi=10.1021/ja0395644|year=2004|month=Jan|author=Ma, C; Ding, Y; Moore, D; Wang, X; Wang, Zl|title=Single-crystal CdSe nanosaws.|volume=126|issue=3|pages=708–9|issn=0002-7863|pmid=14733532|journal=Journal of the American Chemical Society}}</ref> They are also used being tested for use in high-efficiency solar cells<ref>{{cite journal|title=Direct carrier multiplication due to inverse Auger scattering in CdSe quantum dots|doi=10.1063/1.1690104|year=2004|author=Califano, Marco|journal=Applied Physics Letters|volume=84|pages=2409|last2=Zunger|first2=Alex|last3=Franceschetti|first3=Alberto}}</ref><ref>{{cite journal|doi=10.1063/1.2142092|title=Effect of electronic structure on carrier multiplication efficiency: Comparative study of PbSe and CdSe nanocrystals|year=2005|author=Schaller, Richard D.|journal=Applied Physics Letters|volume=87|pages=253102|last2=Petruska|first2=Melissa A.|last3=Klimov|first3=Victor I.}}</ref><ref>{{cite journal|doi=10.1103/PhysRevLett.96.057408|title=Direct Observation of Electron-to-Hole Energy Transfer in CdSe Quantum Dots|year=2006|author=Hendry, E.|journal=Physical Review Letters|volume=96|pages=057408|pmid=16486988|last2=Koeberg|first2=M|last3=Wang|first3=F|last4=Zhang|first4=H|last5=De Mello Donegá|first5=C|last6=Vanmaekelbergh|first6=D|last7=Bonn|first7=M|issue=5|bibcode=2006PhRvL..96e7408H}}</ref> CdSe is also a suitable material for making [[thin-film transistor|thin-film transistors]] (TFTs).<ref> J. DeBaets et al, "High-voltage polycrystalline CdSe thin-film transistors", IEEE Trans. Electron Devices, vol. ED-37, pp. 636-639, Mar. 1990, [http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=47767 DOI: 10.1109/16.47767].</ref> TFTs made from this material were used in the first [[Active-matrix_liquid_crystal_display|active-matrix liquid-crystal display]] showing a still picture in 1973.<ref> T.P. Brody, J.A. Asars and G.D. Dixon, "A 6x6 inch 20 lines- per-inch liquid-crystal display panel", IEEE Trans. Electron Devices, vol. ED-20, pp. 995-1001, Nov. 1973, [http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1477437 DOI: 10.1109/T-ED.1973.17780].</ref> However interest in CdSe for this application largely waned after the emergence of [[amorphous silicon]] technology in the late 1970s.

Most of the usefulness of CdSe stems from [[nanoparticles]], that is particles with sizes below 100&nbsp;nm. CdSe particles of this size exhibit a property known as [[quantum confinement]]. Quantum confinement results when the electrons in a material are confined to a very small volume. Quantum confinement is size dependent, meaning the properties of CdSe nanoparticles are tunable based on their size.<ref>[http://www.ringsurf.com/info/Technology_/Nanotechnology/Structures/ Nanotechnology Structures - Quantum Confinement]</ref>

Since CdSe nanoparticles have a size dependent [[fluorescence]] spectrum, they are finding applications in optical devices such as [[laser diode]]s. Using these particles, engineers are able to manufacture laser diodes that cover a large part of the [[electromagnetic spectrum]].<ref>{{cite journal|author=Colvin, V. L.; Schlamp, M. C.; Alivisatos, A. P.|journal= Nature |year=1994|volume= 370|page= 354|doi=10.1038/370354a0|title=Light-emitting diodes made from cadmium selenide nanocrystals and a semiconducting polymer|issue=6488}}</ref>

Along similar lines, doctors are developing these materials for use in biomedical imaging applications. Human tissue is permeable to far [[infra-red]] light. By injecting appropriately prepared CdSe nanoparticles into injured tissue, it may be possible to image the tissue in those injured areas.<ref>{{cite journal|author= Chan, W. C.; Nie, S. M.|journal= Science |year=1998|volume= 281|page= 2016|doi= 10.1126/science.281.5385.2016|title= Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection|pmid=9748158|issue=5385}}</ref><ref>{{cite journal|author=Bruchez, M.;Moronne, M.; Gin, P.; Weiss, S.; Alivisatos, A. P. |journal=Science |year=1998|volume= 281|page=2013}}</ref>

Cadmium is a toxic heavy metal and appropriate precautions should be taken when handling it and its compounds. Selenides are toxic in large amounts.<ref>Additional safety information available at www.msdsonline.com, search 'cadmium selenide.'</ref>

{{reflist|2}}

===Related materials===

*[[Cadmium sulfide]]

*[[Cadmium telluride]]

*[[Zinc selenide]]

*[[Mercury selenide]]

*[http://www.npi.gov.au/database/substance-info/profiles/17.html National Pollutant Inventory - Cadmium and compounds]

[[Category:Semiconductor materials]]

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