Cadmium oxide

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Cadmium oxide
Oxid kademnaty.JPG
NaCl polyhedra.png
Names
IUPAC name
Cadmium oxide
Other names
Cadmium(II) oxide,
Cadmium monoxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.770 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 215-146-2
PubChem CID
RTECS number
  • EV1925000
UNII
UN number 2570
  • InChI=1S/Cd.O Yes check.svgY
    Key: CXKCTMHTOKXKQT-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/Cd.O/rCdO/c1-2
    Key: CXKCTMHTOKXKQT-MBQGENNCAM
  • [Cd]=O
Properties
CdO
Molar mass 128.413 g·mol−1
Appearancecolorless powder (alpha form)
red-brown crystal (beta form) [1]
Odor odorless
Density 8.15 g/cm3(crystalline),
6.95 g/cm3 (amorphous) [2] solid.
Melting point 900–1,000 °C (1,650–1,830 °F; 1,170–1,270 K)
decomposition of amorphous form [3]
Boiling point 1,559 °C (2,838 °F; 1,832 K) sublimation [3]
4.8 mg/L (18 °C) [4]
Solubility soluble in dilute acid
slowly soluble in ammonium salts
insoluble in alkalies
Vapor pressure 0.13 kPa (1000 °C)
2.62 kPa (1200 °C)
61.4 kPa (1500 °C) [5]
Band gap 2.18 eV
Electron mobility 531 cm2/V·s
-3.0·10−5 cm3/mol
Thermal conductivity 0.7 W/m·K
2.49
Structure
cubic, cF8
Fm3m, No. 225
a = 4.6958 Å
Thermochemistry
43.64 J/mol·K [4]
Std molar
entropy (S⦵298)
55 J/mol·K [6]
−258 kJ/mol [5] [6]
-229.3 kJ/mol [4]
Hazards
GHS labelling:
GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg [7]
Danger
H330, H341, H350, H361, H372, H410 [7]
P201, P260, P273, P281, P284, P310 [7]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
4
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
72 mg/kg (oral, rat) [8]
72 mg/kg (oral, mouse) [9]
500 mg/m3 (rat, 10 min)
2500 mg/m3 (rabbit, 10 min)
3500 mg/m3 (guinea pig, 10 min)
4000 mg/m3 (dog, 10 min)
780 mg/m3 (rat, 10 min)
340 mg/m3 (mouse, 10 min)
3000 mg/m3 (rabbit, 15 min)
3000 mg/m3 (guinea pig, 15 min)
400 mg/m3 (dog, 10 min) [9]
NIOSH (US health exposure limits):
PEL (Permissible)
[1910.1027] TWA 0.005 mg/m3 (as Cd) [10]
REL (Recommended)
Ca [10]
IDLH (Immediate danger)
Ca [9 mg/m3 (as Cd)] [10]
Safety data sheet (SDS) [ dead link ]
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).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

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. [11] It occurs naturally as the rare mineral monteponite. Cadmium oxide can be found as a colorless amorphous powder or as brown or red crystals. [12] Cadmium oxide is an n-type semiconductor [13] with a band gap of 2.18 eV (2.31 eV) at room temperature (298 K). [14]

Contents

Production and structure

Since cadmium compounds are often found in association with zinc ores, cadmium oxide is a common by-product of zinc refining. [15] 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. [16] Cadmium oxide is prepared commercially by oxidizing cadmium vapor in air. [17]

Uses

Cadmium oxide is used in cadmium plating baths, electrodes for storage batteries, cadmium salts, catalysts, ceramic glazes, phosphors, and nematocide. [12] Major uses for cadmium oxide are as an ingredient for electroplating baths, optoelectronic devices, and in pigments. [18]

Transparent conductor

CdO is used as a transparent conductive material, [19] which was prepared as a transparent conducting film as early as 1907 by Karl Baedeker. [20] 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. [21] CdO microparticles undergo bandgap excitation when exposed to UV-A light and is also selective in phenol photodegradation. [22]

Cadmium plating

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. [23]

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. [12] Cadmium will oxidize at room temperatures to form CdO. [23] Cadmium vapor and steam will form CdO and hydrogen in a reversible reaction. [23]

Related Research Articles

<span class="mw-page-title-main">Sodium cyanide</span> Chemical compound

Sodium cyanide is a poisonous compound with the formula NaCN. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its high reactivity toward metals. It is a moderately strong base.

<span class="mw-page-title-main">Cadmium arsenide</span> Chemical compound

Cadmium arsenide (Cd3As2) is an inorganic semimetal in the II-V family. It exhibits the Nernst effect.

<span class="mw-page-title-main">Cadmium sulfide</span> Chemical compound

Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow salt. It occurs in nature with two different crystal structures as the rare minerals greenockite and hawleyite, but is more prevalent as an impurity substituent in the similarly structured zinc ores sphalerite and wurtzite, which are the major economic sources of cadmium. As a compound that is easy to isolate and purify, it is the principal source of cadmium for all commercial applications. Its vivid yellow color led to its adoption as a pigment for the yellow paint "cadmium yellow" in the 18th century.

<span class="mw-page-title-main">Cadmium sulfate</span> Chemical compound

Cadmium sulfate is the name of a series of related inorganic compounds with the formula CdSO4·xH2O. The most common form is the monohydrate CdSO4·H2O, but two other forms are known CdSO4·8⁄3H2O and the anhydrous salt (CdSO4). All salts are colourless and highly soluble in water.

<span class="mw-page-title-main">Cadmium chloride</span> Chemical compound

Cadmium chloride is a white crystalline compound of cadmium and chloride, with the formula CdCl2. This salt is a hygroscopic solid that is highly soluble in water and slightly soluble in alcohol. The crystal structure of cadmium chloride (described below), is a reference for describing other crystal structures. Also known are CdCl2•H2O and the hemipenahydrate CdCl2•2.5H2O.

<span class="mw-page-title-main">Cadmium selenide</span> Chemical compound

Cadmium selenide is an inorganic compound with the formula CdSe. It is a black to red-black solid that is classified as a II-VI semiconductor of the n-type. It is a pigment but applications are declining because of environmental concerns

<span class="mw-page-title-main">Chromium(III) oxide</span> Chemical compound

Chromium(III) oxide is an inorganic compound with the formula Cr
2O
3. It is one of the principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.

Ethylenediamine (abbreviated as en when a ligand) is the organic compound with the formula C2H4(NH2)2. This colorless liquid with an ammonia-like odor is a basic amine. It is a widely used building block in chemical synthesis, with approximately 500,000 tonnes produced in 1998. Ethylenediamine is the first member of the so-called polyethylene amines.

<span class="mw-page-title-main">Germane</span> Chemical compound

Germane is the chemical compound with the formula GeH4, and the germanium analogue of methane. It is the simplest germanium hydride and one of the most useful compounds of germanium. Like the related compounds silane and methane, germane is tetrahedral. It burns in air to produce GeO2 and water. Germane is a group 14 hydride.

<span class="mw-page-title-main">Cadmium fluoride</span> Chemical compound

Cadmium fluoride (CdF2) is a mostly water-insoluble source of cadmium used in oxygen-sensitive applications, such as the production of metallic alloys. In extremely low concentrations (ppm), this and other fluoride compounds are used in limited medical treatment protocols. Fluoride compounds also have significant uses in synthetic organic chemistry. The standard enthalpy has been found to be -167.39 kcal. mole−1 and the Gibbs energy of formation has been found to be -155.4 kcal. mole−1, and the heat of sublimation was determined to be 76 kcal. mole−1.

<span class="mw-page-title-main">Copper(I) cyanide</span> Chemical compound

Copper(I) cyanide is an inorganic compound with the formula CuCN. This off-white solid occurs in two polymorphs; impure samples can be green due to the presence of Cu(II) impurities. The compound is useful as a catalyst, in electroplating copper, and as a reagent in the preparation of nitriles.

<span class="mw-page-title-main">Zinc nitride</span> Chemical compound

Zinc nitride (Zn3N2) is an inorganic compound of zinc and nitrogen, usually obtained as (blue)grey crystals. It is a semiconductor. In pure form, it has the anti-bixbyite structure.

<span class="mw-page-title-main">Gallium(III) oxide</span> Chemical compound

Gallium(III) oxide is an inorganic compound and ultra-wide-bandgap semiconductor with the formula Ga2O3. It is actively studied for applications in power electronics, phosphors, and gas sensing. The compound has several polymorphs, of which the monoclinic β-phase is the most stable. The β-phase’s bandgap of 4.7–4.9 eV and large-area, native substrates make it a promising competitor to GaN and SiC-based power electronics applications and solar-blind UV photodetectors. The orthorhombic ĸ-Ga2O3 is the second most stable polymorph. The ĸ-phase has shown instability of subsurface doping density under thermal exposure. Ga2O3 exhibits reduced thermal conductivity and electron mobility by an order of magnitude compared to GaN and SiC, but is predicted to be significantly more cost-effective due to being the only wide-bandgap material capable of being grown from melt. β-Ga2O3 is thought to be radiation-hard, which makes it promising for military and space applications.

<span class="mw-page-title-main">Rhodium(III) oxide</span> Chemical compound

Rhodium(III) oxide (or Rhodium sesquioxide) is the inorganic compound with the formula Rh2O3. It is a gray solid that is insoluble in ordinary solvents.

<span class="mw-page-title-main">Cadmium nitrate</span> Chemical compound

Cadmium nitrate describes any of the related members of a family of inorganic compounds with the general formula , the most commonly encountered form being the tetrahydrate. The anhydrous form is volatile, but the others are colourless crystalline solids that are deliquescent, tending to absorb enough moisture from the air to form an aqueous solution. Like other cadmium compounds, cadmium nitrate is known to be carcinogenic.

<span class="mw-page-title-main">Cadmium acetate</span> Chemical compound

Cadmium acetate is the chemical compound with the formula Cd(O2CCH3)2(H2O)2. The compound is marketed both as the anhydrous form and as a dihydrate, both of which are white or colorless. Only the dihydrate has been verified by X-ray crystallography.

<span class="mw-page-title-main">Cadmium cyanide</span> Chemical compound

Cadmium cyanide is an inorganic compound with the formula Cd(CN)2. It is a white crystalline compound that is used in electroplating. It is very toxic, along with other cadmium and cyanide compounds.

<span class="mw-page-title-main">Cadmium hydroxide</span> Chemical compound

Cadmium hydroxide is an inorganic compound with the formula Cd(OH)2. It is a white crystalline ionic compound that is a key component of nickel–cadmium battery.

<span class="mw-page-title-main">Transparent conducting film</span> Optically transparent and electrically conductive material

Transparent conducting films (TCFs) are thin films of optically transparent and electrically conductive material. They are an important component in a number of electronic devices including liquid-crystal displays, OLEDs, touchscreens and photovoltaics. While indium tin oxide (ITO) is the most widely used, alternatives include wider-spectrum transparent conductive oxides (TCOs), conductive polymers, metal grids and random metallic networks, carbon nanotubes (CNT), graphene, nanowire meshes and ultra thin metal films.

<span class="mw-page-title-main">Cadmium tetrafluoroborate</span> Chemical compound

Cadmium tetrafluoroborate is an ionic, chemical compound with the formula Cd(BF4)2. It is a crystalline solid, which is colorless and odorless. Cadmium tetrafluoroborate is most frequently used in the industrial production of high-strength steels, its purpose being to prevent hydrogen absorption, a source of post-production cracking of the metal, in the treated steels. Another application of the chemistry of cadmium tetrafluoroborate is fine tuning of the size of cadmium telluride nanomaterials.

References

  1. ↑ Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. ISBN   0-07-049439-8.
  2. ↑ "NIOSH Pocket Guide to Chemical Hazards" . Retrieved 2007-02-16.
  3. 1 2 "INCHEM: Chemical Safety Information from Intergovernmental Organizations" . Retrieved 2007-02-16.
  4. 1 2 3 "Cadmium oxide".
  5. 1 2 Cadmium oxide in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-05-23)
  6. 1 2 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A21. ISBN   978-0-618-94690-7.
  7. 1 2 3 Sigma-Aldrich Co., Cadmium oxide. Retrieved on 2014-05-23.
  8. ↑ https://chem.nlm.nih.gov/chemidplus/rn/1306-19-0 [ dead link ]
  9. 1 2 "Cadmium compounds (as Cd)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  10. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0087". National Institute for Occupational Safety and Health (NIOSH).
  11. ↑ Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN   0-19-855370-6.
  12. 1 2 3 Lewis, Richard J. Sr., Hawley's condensed chemical dictionary, 13th ed., 1997, p. 189
  13. ↑ T. L. Chu; Shirley S. Chu (1990). "Degenerate cadmium oxide films for electronic devices". Journal of Electronic Materials. 19 (9): 1003–1005. Bibcode:1990JEMat..19.1003C. doi:10.1007/BF02652928. S2CID   95361658.
  14. ↑ S. K. Vasheghani Farahani; et al. (2013). "Temperature dependence of the direct bandgap and transport properties of CdO". Applied Physics Letters. 102 (2): 022102. Bibcode:2013ApPhL.102b2102V. doi:10.1063/1.4775691.
  15. ↑ "Cadmium and compounds fact sheet". Archived from the original on 2006-12-10. Retrieved 2007-02-16. Archived 2006-12-10 at the Wayback Machine
  16. ↑ Holleman, A. F.; Wiberg, E. Inorganic Chemistry. Academic Press: San Diego, 2001. ISBN   0-12-352651-5.
  17. ↑ Hampel, C. A.; Hawley, G. G. (1973). The encyclopedia of Chemistry (3rd ed.). New York, Van Nostrand Reinhold. p.  169. ISBN   9780442230951.
  18. ↑ Clifford A. Hampel and Gessner G. Hawley, The encyclopedia of Chemistry, 3rd Ed., 1973, p. 169
  19. ↑ Varkey, A (1994). "Transparent conducting cadmium oxide thin films prepared by a solution growth technique". Thin Solid Films. 239 (2): 211–213. Bibcode:1994TSF...239..211V. doi:10.1016/0040-6090(94)90853-2.
  20. ↑ Dou, Y (1998). "N-type doping in CdO ceramics: a study by EELS and photoemission spectroscopy". Surface Science. 398 (1–2): 241–258. Bibcode:1998SurSc.398..241D. doi:10.1016/S0039-6028(98)80028-9.
  21. ↑ Lokhande, B (2004). "Studies on cadmium oxide sprayed thin films deposited through non-aqueous medium". Materials Chemistry and Physics. 84 (2–3): 238–242. doi:10.1016/S0254-0584(03)00231-1.
  22. ↑ Karunakaran, C; Dhanalakshmi, R (2009). "Selectivity in photocatalysis by particulate semiconductors". Central European Journal of Chemistry. 7 (1): 134. doi: 10.2478/s11532-008-0083-7 .
  23. 1 2 3 Clifford A. Hampel, Rare Metals Handbook, 1954, p. 87-103
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