Cadmium oxide: Difference between revisions
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'''Cadmium oxide''' is an [[inorganic compound]] with the [[chemical formula|formula]] [[cadmium|Cd]]O. It is one of the main precursors to other cadmium compounds It crystallizes in a cubic rocksalt lattice like [[sodium chloride]], with [[octahedral]] [[cation]] and [[anion]] centers.<ref>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.</ref> It rarely occurs naturally as the mineral monteponite. Cadmium oxide can found as a colorless amorphous powder or as brown or red crystals.<ref name="Lewis, Richard J. 1997, p. 189">Lewis, Richard J., Sr., Hawley's condensed chemical dictionary, 13th ed., 1997, p. 189</ref> Cadmium oxide is n-type semiconductor.<ref>{{cite journal|author=T. L. Chu and Shirley S. Chu|journal=Journal of Electronic Materials|volume=19|issue=9|year=1990|page=1003-1005}}</ref> |
'''Cadmium oxide''' is an [[inorganic compound]] with the [[chemical formula|formula]] [[cadmium|Cd]]O. It is one of the main precursors to other cadmium compounds It crystallizes in a cubic rocksalt lattice like [[sodium chloride]], with [[octahedral]] [[cation]] and [[anion]] centers.<ref>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.</ref> It rarely occurs naturally as the mineral monteponite. Cadmium oxide can found as a colorless amorphous powder or as brown or red crystals.<ref name="Lewis, Richard J. 1997, p. 189">Lewis, Richard J., Sr., Hawley's condensed chemical dictionary, 13th ed., 1997, p. 189</ref> Cadmium oxide is n-type semiconductor.<ref>{{cite journal|author=T. L. Chu and Shirley S. Chu|journal=Journal of Electronic Materials|volume=19|issue=9|year=1990|page=1003-1005|doi=10.1007/BF02652928|title=Degenerate cadmium oxide films for electronic devices}}</ref> |
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==Production and structure== |
==Production and structure== |
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==Uses== |
==Uses== |
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CdO is used as a transparent conductive material,<ref>{{cite journal|doi=10.1016/0040-6090(94)90853-2}}</ref> which was prepared as a transparent conducting film back in 1907.<ref>{{cite journal|doi=10.1016/S0039-6028(98)80028-9}}</ref> Cadmium oxide in the form of thin films has been used in applications such as photodiodes, phototransistors, photovoltaic cells, transparent electrodes, liquid crystal displays, IR detectors, and anti reflection coatings.<ref>{{cite journal|doi=10.1016/S0254-0584(03)00231-1}}</ref> CdO microparticles undergo bandgap excitation when exposed to [[Ultraviolet|UV-A]] light and is also selective in phenol photodegradation.<ref>{{cite journal|doi=10.2478/s11532-008-0083-7|format=free download pdf}}</ref> |
CdO is used as a transparent conductive material,<ref>{{cite journal|doi=10.1016/0040-6090(94)90853-2|title=Transparent conducting cadmium oxide thin films prepared by a solution growth technique|year=1994|last1=Varkey|first1=A|journal=Thin Solid Films|volume=239|pages=211}}</ref> which was prepared as a transparent conducting film back in 1907.<ref>{{cite journal|doi=10.1016/S0039-6028(98)80028-9|title=N-type doping in CdO ceramics: a study by EELS and photoemission spectroscopy|year=1998|last1=Dou|first1=Y|journal=Surface Science|volume=398|pages=241}}</ref> Cadmium oxide in the form of thin films has been used in applications such as photodiodes, phototransistors, photovoltaic cells, transparent electrodes, liquid crystal displays, IR detectors, and anti reflection coatings.<ref>{{cite journal|doi=10.1016/S0254-0584(03)00231-1|title=Studies on cadmium oxide sprayed thin films deposited through non-aqueous medium|year=2004|last1=Lokhande|first1=B|journal=Materials Chemistry and Physics|volume=84|pages=238}}</ref> CdO microparticles undergo bandgap excitation when exposed to [[Ultraviolet|UV-A]] light and is also selective in phenol photodegradation.<ref>{{cite journal|doi=10.2478/s11532-008-0083-7|format=free download pdf|pmid=18521924|year=2008|last1=Hancock|first1=L|last2=Beckly|first2=J|last3=Geremia|first3=A|last4=Cooney|first4=R|last5=Cummings|first5=F|last6=Pathan|first6=S|last7=Guo|first7=C|last8=Warren|first8=BF|last9=Mortensen|first9=N|title=Clinical and molecular characteristics of isolated colonic Crohn's disease.|volume=14|issue=12|pages=1667–77|journal=Inflammatory bowel diseases}}</ref> |
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Cadmium oxide is used in cadmium plating baths, electrodes for storage batteries, cadmium salts, catalyst, ceramic glazes, phosphors, and nematocide.<ref name="Lewis, Richard J. 1997, p. 189" /> Major uses for cadmium oxide is as an ingredient for electroplating baths and in pigments.<ref>Clifford A. Hampel and Gessner G. Hawley, The encyclopedia of Chemistry, 3rd Ed., 1973, p. 169</ref> Most commercial electroplating of cadmium is done by electrodeposition from cyanide baths. These cyanide baths consist of cadmium oxide and [[sodium cyanide]] in water, which likely form [[cadmium cyanide]] and [[sodium hydroxide]]. A typical formula is 32 g/L Cadmium oxide and 75 g/L sodium cyanide. The cadmium concentration may vary by as much as 50%. Brighteners are usually added to the bath and the plating is done at room temperature with high purity cadmium anodes.<ref name="Clifford A. Hampel 1954, p. 87-103">Clifford A. Hampel, Rare Metals Handbook, 1954, p. 87-103</ref> |
Cadmium oxide is used in cadmium plating baths, electrodes for storage batteries, cadmium salts, catalyst, ceramic glazes, phosphors, and nematocide.<ref name="Lewis, Richard J. 1997, p. 189" /> Major uses for cadmium oxide is as an ingredient for electroplating baths and in pigments.<ref>Clifford A. Hampel and Gessner G. Hawley, The encyclopedia of Chemistry, 3rd Ed., 1973, p. 169</ref> Most commercial electroplating of cadmium is done by electrodeposition from cyanide baths. These cyanide baths consist of cadmium oxide and [[sodium cyanide]] in water, which likely form [[cadmium cyanide]] and [[sodium hydroxide]]. A typical formula is 32 g/L Cadmium oxide and 75 g/L sodium cyanide. The cadmium concentration may vary by as much as 50%. Brighteners are usually added to the bath and the plating is done at room temperature with high purity cadmium anodes.<ref name="Clifford A. Hampel 1954, p. 87-103">Clifford A. Hampel, Rare Metals Handbook, 1954, p. 87-103</ref> |
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Revision as of 01:02, 3 October 2009
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| Names | |
|---|---|
| IUPAC name
Cadmium oxide
| |
| Other names
Cadmium(II) oxide,
Cadmium monoxide | |
| Identifiers | |
| ECHA InfoCard | 100.013.770 |
| EC Number |
|
| RTECS number |
|
| UN number | 2570 |
CompTox Dashboard (EPA)
|
|
| Properties | |
| CdO | |
| Molar mass | 128.413 g·mol−1 |
| Appearance | colorless powder (alpha form) red-brown crystal (beta form) [1] |
| Density | 8.150 g/cm3(crystalline), 6.95 g/cm3 (amorphous)[2] solid. |
| Melting point | 900-1000 °C |
| Boiling point | 1559 °C |
| insoluble | |
| Solubility in acid and alkaline | degrades |
| Electron mobility | 531 cm2/V s |
| -3×10−5 cm3/mol | |
| Thermal conductivity | 0.7 W/m-K |
| Structure | |
| cubic, cF8 | |
| Fm3m, No. 225 | |
a = 4.6958 Å
| |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Related compounds | |
Other anions
|
Cadmium sulfide Cadmium selenide Cadmium telluride |
Other cations
|
Zinc oxide Mercury oxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Cadmium oxide is an inorganic compound with the formula CdO. It is one of the main precursors to other cadmium compounds It crystallizes in a cubic rocksalt lattice like sodium chloride, with octahedral cation and anion centers.[4] It rarely occurs naturally as the mineral monteponite. Cadmium oxide can found as a colorless amorphous powder or as brown or red crystals.[5] Cadmium oxide is n-type semiconductor.[6]
Production and structure
Since cadmium compounds are often found in association with zinc ores, cadmium oxide is a common by-product of zinc refining.[7]. It is produced by burning elemental cadmium in air. Pyrolysis of other cadmium compounds, such as the nitrate or the carbonate, also affords this oxide. When pure, it is red but CdO is unusual in being available in many differing colours due to its tendency to form defect structures resulting from anion vacancies.[8] Cadmium oxide is prepared commercially by oxidizing cadmium vapor in air.[9]
Uses
CdO is used as a transparent conductive material,[10] which was prepared as a transparent conducting film back in 1907.[11] Cadmium oxide in the form of thin films has been used in applications such as photodiodes, phototransistors, photovoltaic cells, transparent electrodes, liquid crystal displays, IR detectors, and anti reflection coatings.[12] CdO microparticles undergo bandgap excitation when exposed to UV-A light and is also selective in phenol photodegradation.[13]
Cadmium oxide is used in cadmium plating baths, electrodes for storage batteries, cadmium salts, catalyst, ceramic glazes, phosphors, and nematocide.[5] Major uses for cadmium oxide is as an ingredient for electroplating baths and in pigments.[14] Most commercial electroplating of cadmium is done by electrodeposition from cyanide baths. These cyanide baths consist of cadmium oxide and sodium cyanide in water, which likely form cadmium cyanide and sodium hydroxide. A typical formula is 32 g/L Cadmium oxide and 75 g/L sodium cyanide. The cadmium concentration may vary by as much as 50%. Brighteners are usually added to the bath and the plating is done at room temperature with high purity cadmium anodes.[15]
Reactivity
CdO is a basic oxide and is thus attacked by aqueous acids to give solutions of [Cd(H2O)6]2+. Upon treatment with strong alkaline solutions, [Cd(OH)4]2- forms. A thin coat of cadmium oxide forms on the surface of cadmium in moist air at room temperature.[14] Cadmium will oxidize at room temperatures to form CdO.[15] Cadmium vapor and steam will form CdO and hydrogen in a reversible reaction.[15]
Health Risks
Cadmium oxide is a known carcinogen and inhaling fumes or vapors may be fatal.[5] Cadmium compounds are considered carcinogenic.[2] For further information, consult the MSDS.[16]
References
- ^ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. ISBN 0070494398.
- ^ a b "NIOSH Pocket Guide to Chemical Hazards". Retrieved 2007-02-16.
- ^ a b "INCHEM: Chemical Safety Information from Intergovernmental Organizations". Retrieved 2007-02-16. Cite error: The named reference "INCHEM_sheet" was defined multiple times with different content (see the help page).
- ^ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
- ^ a b c Lewis, Richard J., Sr., Hawley's condensed chemical dictionary, 13th ed., 1997, p. 189
- ^ T. L. Chu and Shirley S. Chu (1990). "Degenerate cadmium oxide films for electronic devices". Journal of Electronic Materials. 19 (9): 1003-1005. doi:10.1007/BF02652928.
- ^ "Cadmium and compounds fact sheet". Retrieved 2007-02-16.
- ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ Hampel, C. A. and Hawley, G. G. (1973). The encyclopedia of Chemistry. p. 169.
{{cite book}}: Unknown parameter|editition=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Varkey, A (1994). "Transparent conducting cadmium oxide thin films prepared by a solution growth technique". Thin Solid Films. 239: 211. doi:10.1016/0040-6090(94)90853-2.
- ^ Dou, Y (1998). "N-type doping in CdO ceramics: a study by EELS and photoemission spectroscopy". Surface Science. 398: 241. doi:10.1016/S0039-6028(98)80028-9.
- ^ Lokhande, B (2004). "Studies on cadmium oxide sprayed thin films deposited through non-aqueous medium". Materials Chemistry and Physics. 84: 238. doi:10.1016/S0254-0584(03)00231-1.
- ^ Hancock, L; Beckly, J; Geremia, A; Cooney, R; Cummings, F; Pathan, S; Guo, C; Warren, BF; Mortensen, N (2008). "Clinical and molecular characteristics of isolated colonic Crohn's disease". Inflammatory bowel diseases. 14 (12): 1667–77. doi:10.2478/s11532-008-0083-7. PMID 18521924.
{{cite journal}}:|format=requires|url=(help) - ^ Clifford A. Hampel and Gessner G. Hawley, The encyclopedia of Chemistry, 3rd Ed., 1973, p. 169
- ^ a b c Clifford A. Hampel, Rare Metals Handbook, 1954, p. 87-103
- ^ "INDG391 - Cadmium and you - working with Cadmium - are you at risk ?" (PDF). UK Health and Safety Executive Leaflet. Retrieved 2007-02-16.
External links
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