Information about Cadmium Selenide
| Cadmium selenide | |
|---|---|
| IUPAC name | Cadmium selenide |
| Other names | Cadmium(II) selenide Cadmoselite |
| Identifiers | |
| CAS number | |
| SMILES | Cd=Se |
| Properties | |
| Molecular formula | CdSe |
| Molar mass | 191.37 g/mol |
| Appearance | Greenish-brown or dark red solid powder |
| Density | 5.816 g/cm3, solid |
| Melting point | 1268 °C (1541 K) |
| Solubility in water | Insoluble |
| Structure | |
| Crystal structure | hexagonal (wurtzite) |
| Related Compounds | |
| Other anions | Cadmium sulfide Cadmium telluride |
| Other cations | Zinc selenide Mercury(II) selenide Silver selenide Indium selenide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 C, 100 kPa) | |
Cadmium selenide (CdSe) is a solid, binary compound of cadmium and selenium. Common names for this compound are cadmium (II) selenide, cadmium selenide, and cadmoselite.
Cadmium selenide is a 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 nanoparticles. 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.
Production
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.[1]However, cadmium selenide in the bulk form is not very interesting. The most interesting form of cadmium selenide is known as 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.[2]
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.[3]
- Me2Cd + TOPSe → CdSe + (byproducts).
Synthesis in structured environments refers to the production of cadmium selenide in liquid crystal or surfactant solutions. The addition to surfactants to solutions often results in a phase change in the solution leading to a liquid crystallinity. A liquid crystal is similar to a solid crystal in that the solution has long range translational order. Examples of this ordering are layered alternating sheets of solution and surfactant, micelles, or even a hexagonal arrangement of rods.
High temperature pyrolysis synthesis is usually carried out using an aerosol containing a mixture of volatile cadmium and selenium precursors. The precursor aerosol is then carried through a furnace with an inert gas, such as hydrogen, nitrogen, or argon. In the furnace the precursors react to form CdSe as well as several by-products.[2]
Applications
Cadmium selenide in its wurtzite crystal structure is an important II-VI semiconductor. As a semiconductor CdSe has a band gap of 1.74 eV at 300 K. It is an n-type semiconductor, which is difficult to dope p-type, however p-type doping has been achieved using nitrogen.[5] CdSe is also being developed for use in opto-electronic devices, laser diodes, nanosensing, and biomedical imaging.[6] They are also used being tested for use in high-efficiency solar cells[7][8][9]Most of the usefulness of CdSe stems from nanoparticles. Nanoparticles are just what the name implies, particles of CdSe that are 1–100 nm (1 nm = 10−9 m) in size. 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.[10]
Since CdSe nanoparticles have a size dependent fluorescence spectrum, they are finding applications in optical devices such as laser diodes. Using these particles, engineers are able to manufacture laser diodes that cover a large part of the electromagnetic spectrum.[11]
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.[12]
Safety information
Cadmium is a toxic heavy metal and appropriate precautions should be taken when handling it and its compounds. Selenides are toxic in large amounts. See MSDS[13].References
1. ^ [1]
2. ^ Didenko, Y. Y.; Suslick K. S. Chemical Aerosol Flow Synthesis of Semiconductor Nanoparticles. J. Am. Chem. Soc.; (Communication); 2005; 127(35); 12196-12197
3. ^ Bawendi et al. Synthesis of CdE Semiconductor Nanocrystallites. J. Am. Chem. Soc. 1993, 115, 8706-8715
4. ^ Didenko, Y. Y.; Suslick K. S. Chemical Aerosol Flow Synthesis of Semiconductor Nanoparticles. J. Am. Chem. Soc.; (Communication); 2005; 127(35); 12196-12197
5. ^ T Ohtsuka, J Kawamata, Z Zhu, T Yao, Applied Physics Letters, 65, 466-468, (1994)
6. ^ Christopher Ma et al. Single-Crystal CdSe Nanosaws. J. AM. CHEM. SOC. 2004, 126, 708-709
7. ^ Direct carrier multiplication due to inverse Auger scattering in CdSe quantum dots. Appl. Phys. Lett., Vol. 84, No. 13, 29 March 2004.
8. ^ Effect of electronic structure on carrier multiplication efficiency: Comparative study of PbSe and CdSe nanocrystals. Appl. Phys. Lett. 87, 253102 (2005).
9. ^ Direct Observation of Electron-to-Hole Energy Transfer in CdSe Quantum Dots. PRL 96, 057408 (2006).
10. ^ [2]
11. ^ Colvin, V. L.; Schlamp, M. C.; Alivisato, A. P. Nature 1994, 370, 354.
12. ^ (a) Chan, W. C.; Nie, S. M. Science 1998, 281, 2016. (b) Bruchez, M.;Moronne, M.; Gin, P.; Weiss, S.; Alivisatos, A. P. Science 1998, 281, 2013.
13. ^ Additional safety information available at www.msdsonline.com, search 'cadmium selenide.'
2. ^ Didenko, Y. Y.; Suslick K. S. Chemical Aerosol Flow Synthesis of Semiconductor Nanoparticles. J. Am. Chem. Soc.; (Communication); 2005; 127(35); 12196-12197
3. ^ Bawendi et al. Synthesis of CdE Semiconductor Nanocrystallites. J. Am. Chem. Soc. 1993, 115, 8706-8715
4. ^ Didenko, Y. Y.; Suslick K. S. Chemical Aerosol Flow Synthesis of Semiconductor Nanoparticles. J. Am. Chem. Soc.; (Communication); 2005; 127(35); 12196-12197
5. ^ T Ohtsuka, J Kawamata, Z Zhu, T Yao, Applied Physics Letters, 65, 466-468, (1994)
6. ^ Christopher Ma et al. Single-Crystal CdSe Nanosaws. J. AM. CHEM. SOC. 2004, 126, 708-709
7. ^ Direct carrier multiplication due to inverse Auger scattering in CdSe quantum dots. Appl. Phys. Lett., Vol. 84, No. 13, 29 March 2004.
8. ^ Effect of electronic structure on carrier multiplication efficiency: Comparative study of PbSe and CdSe nanocrystals. Appl. Phys. Lett. 87, 253102 (2005).
9. ^ Direct Observation of Electron-to-Hole Energy Transfer in CdSe Quantum Dots. PRL 96, 057408 (2006).
10. ^ [2]
11. ^ Colvin, V. L.; Schlamp, M. C.; Alivisato, A. P. Nature 1994, 370, 354.
12. ^ (a) Chan, W. C.; Nie, S. M. Science 1998, 281, 2016. (b) Bruchez, M.;Moronne, M.; Gin, P.; Weiss, S.; Alivisatos, A. P. Science 1998, 281, 2013.
13. ^ Additional safety information available at www.msdsonline.com, search 'cadmium selenide.'
Related materials
External links
- Quantum Dots in Solar Cells Science News Week of June 3, 2006; Vol. 169, No. 22 , p. 344.
- National Pollutant Inventory - Cadmium and compounds
- National Compound semiconductor roadmap at ONR.
IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. It is developed and kept up to date under the auspices of the International Union of Pure and Applied Chemistry (IUPAC).
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In physics, density is mass m per unit volume V—how heavy something is compared to its size. A small, heavy object, such as a rock or a lump of lead, is denser than a lighter object of the same size or a larger object of the same weight, such as pieces of
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Solubility is a physical property referring to the ability for a given substance, the solute, to dissolve in a solvent.[1] It is measured in terms of the maximum amount of solute dissolved in a solvent at equilibrium. The resulting solution is called a saturated solution.
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Water is a common chemical substance that is essential to all known forms of life.[1] In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor.
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crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a motif, a set of atoms arranged in a particular way, and a lattice. Motifs are located upon the points of a lattice, which is an array of points repeating periodically in three
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Wurtzite is a less frequently encountered mineral form of zinc sulfide, named after French chemist Charles-Adolphe Wurtz.
The crystal structure is a member of the hexagonal crystal system and consists of tetrahedrally coordinated zinc and sulfur atoms that are
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The crystal structure is a member of the hexagonal crystal system and consists of tetrahedrally coordinated zinc and sulfur atoms that are
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ion is an atom or molecule which has lost or gained one or more electrons, making it positively or negatively charged. A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion
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Cadmium sulfide is a chemical compound with the formula CdS. It exists in nature as two different minerals, greenockite and hawleyite.
Greenockite forms hexagonal crystals with the wurtzite structure. It has a yellowish colour with specific gravity of 4.
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Greenockite forms hexagonal crystals with the wurtzite structure. It has a yellowish colour with specific gravity of 4.
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ion is an atom or molecule which has lost or gained one or more electrons, making it positively or negatively charged. A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion
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Zinc selenide (ZnSe), is a light yellow binary solid compound. It is an intrinsic semiconductor with a band gap of about 2.7 eV at 25 °C. It has a standard enthalpy of formation of 177.6 kJ/mol at 25 °C. It adopts a Zincblende lattice structure with lattice constant a=566.
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Mercury selenide (HgSe) is a chemical compound of mercury and selenium. It is a a grey-black crystalline solid semi-metal with a sphalerite structure. The lattice constant is 0.608 nm. The CAS number is [].
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Indium(III) selenide is a compound of indium and selenium. It has potential for use in photovoltaic devices and it has been the subject of extensive research. The two most common forms α- and β- have defect wurtzite structures, however there are five known forms
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standard state of a material is its state at 1 bar (100 kilopascals exactly). This pressure was changed from 1 atm (101.325 kilopascals) by IUPAC in 1990.[1] The standard state of a material can be defined at any given temperature, most commonly 25 degrees Celsius,
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Cadmium (IPA: /ˈkædmiəm/) is a chemical element in the periodic table that has the symbol Cd and atomic number 48.
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4, 6
(strongly acidic oxide)
Electronegativity 2.55 (scale Pauling)
Ionization energies
(more) 1st: 941.0 kJmol−1
2nd: 2045 kJmol−1
3rd: 2973.
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(strongly acidic oxide)
Electronegativity 2.55 (scale Pauling)
Ionization energies
(more) 1st: 941.0 kJmol−1
2nd: 2045 kJmol−1
3rd: 2973.
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A semiconductor is a solid that has electrical conductivity in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically.[1] Semiconductors are tremendously important in technology.
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nanoparticle (or nanopowder or nanocluster or nanocrystal) is a microscopic particle with at least one dimension less than 100 nm. Nanoparticle research is currently an area of intense scientific research, due to a wide variety of potential applications in
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Liquid crystals are substances that exhibit a phase of matter that has properties between those of a conventional liquid, and those of a solid crystal. For instance, a liquid crystal (LC) may flow like a liquid, but have the molecules in the liquid arranged and/or oriented in a
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Surfactants, also known as tensides, are wetting agents that lower the surface tension of a liquid, allowing easier spreading, and lower the interfacial tension between two liquids.
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A micelle (rarely micella, plural micellae) is an aggregate of surfactant molecules dispersed in a liquid colloid.
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Aerosol technically refers to airborne solid particles (also called dust or particulate matter (PM)) or liquid droplets. In casual language, aerosol refers to an aerosol spray can or the output of such a can.
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1, −1
(amphoteric oxide)
Electronegativity 2.20 (Pauling scale) More
Atomic radius 25 pm
Atomic radius (calc.) 53 pm
Covalent radius 37 pm
Van der Waals radius 120 pm
Miscellaneous
Thermal conductivity (300 K) 180.
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(amphoteric oxide)
Electronegativity 2.20 (Pauling scale) More
Atomic radius 25 pm
Atomic radius (calc.) 53 pm
Covalent radius 37 pm
Van der Waals radius 120 pm
Miscellaneous
Thermal conductivity (300 K) 180.
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3, 5, 4, 2
(strongly acidic oxide)
Electronegativity 3.04 (Pauling scale)
Ionization energies
(more) 1st: 1402.3 kJmol−1
2nd: 2856 kJmol−1
3rd: 4578.1 kJmol−1
Atomic radius 65 pm
Atomic radius (calc.
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(strongly acidic oxide)
Electronegativity 3.04 (Pauling scale)
Ionization energies
(more) 1st: 1402.3 kJmol−1
2nd: 2856 kJmol−1
3rd: 4578.1 kJmol−1
Atomic radius 65 pm
Atomic radius (calc.
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Argon (IPA:/ˈɑːgɒn/) is a chemical element designated by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table (noble gases).
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