Lead sulfide (British/Commonwealth English sulphide) is a chemical compound PbS, most often purified from the mineral galena. PbS, PbSe and PbTe lead salts are semiconductors of the IV-VI family. The CAS number of PbS is [1314-87-0][1]. A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Atomic mass 32. ... Minerals are natural compounds formed through geological processes. ... Galena is a lead ore. ... Lead selenide (PbSe), or lead(II) selenide, a selenide of lead, is a semiconductor material. ... Lead telluride is a compound of lead and tellurium (PbTe); it is a narrow gap semiconductor. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ...

Applications

Lead sulfide and several other lead salts are used as detection element material in various infra-red sensors. Of these, PbS (lead sulfide) is one of the oldest and most commonly used. It is used for eg. infrared detectors. General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... A magnified crystal of a salt (halite/sodium chloride) In chemistry, a salt is any ionic compound composed of positively charged cations and negatively charged anions so that the product is neutral and without a net charge. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ... The term sulfide (sulphide in British) refers to several types of chemical compounds containing sulfur in its lowest oxidation number of -2. ... An infrared detector is a detector that reacts to infrared (IR) radiation. ...

When used as IR detection element material they are classified as photon detectors: this means that unlike thermal detectors (the other major type), they react directly to the photons of incoming light radiation hitting the material. Thermal detectors react only to the eventual temperature rise in the material caused by the energy from the photons. Because of this, radiation can then be measured in two ways: either by detecting the tiny electrical current the photons cause when they hit the PbS surface, or by measuring the change in its electrical resistance. Measuring the resistance change is the more commonly used method. In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... This article is about the atmospheric phenomenon. ... In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ... Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ...

At room temperature, PbS elements are sensitive to radiation at wavelengths between approximately 1 and 2.5 μm. This corresponds to the shorter wavelengths in the IR band, and is called near-IR, a term which refers to the fact that it is close to the wavelengths of visible light. Only very hot objects emit radiation in these wavelengths. Room temperature, in laboratory reports, is taken to be roughly 21–23 degrees Celsius (69-73 degrees Fahrenheit), or 294–296 kelvins. ... The wavelength is the distance between repeating units of a wave pattern. ... A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ... A band is a small section of the spectrum of radio communication frequencies, in which channels are usually used or set aside for the same purpose. ... The optical spectrum (light or visible spectrum) is the portion of the electromagnetic spectrum that is visible to the human eye. ...

Cooling the PbS elements, for example using pressurised or liquified gas or a Peltier system shifts its sensitivity range to between approximately 2 and 4 μm. Objects which emit radiation in these wavelengths still have to be quite hot; several hundred degrees Celsius; but not as hot as those which are detectable by uncooled sensors. Peltier may refer to: Peltier-Seebeck effect, a thermoelectric conversion Jean Charles Athanase Peltier, who documented the Peltier effect Leonard Peltier, who was convicted of the murder of two FBI Agents Leslie Peltier, an astronomer See also Pelletier This is a disambiguation page: a list of articles associated with the... A degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701-1744), who first proposed a similar system in 1742. ...

Other compounds used for this purpose include indium antimonide (InSb) and HgCdTe, which have somewhat better properties for detecting the longer IR wavelengths. Indium antimonide (InSb) is a narrow gap semiconductor material from the group the (III-V group) used in infrared detectors, including thermal imaging cameras, FLIR systems, infrared homing missile guidance systems, and in infrared astronomy. ... HgCdTe or Mercury cadmium telluride (also Cadmium Mercury Telluride or CMT) is an alloy of CdTe and HgTe and is sometimes claimed to be the third semiconductor of technological importance after Si and GaAs. ...

The high dielectric constant of PbS leads to relatively slow detectors (compared to silicon, germanium, InSb or HgCdTe). General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... General Name, Symbol, Number germanium, Ge, 32 Chemical series metalloids Group, Period, Block 14, 4, p Appearance grayish white Atomic mass 72. ...

PbS can be formed as nanocrystals.

Safety Information

PbS is toxic due to the lead content. Lead can acccumulate in the body (see lead poisoning). Lead poisoning is a medical condition, also known as saturnism, plumbism or painters colic, caused by increased blood serum lead levels. ...

Astronomy

Elevations above 2.6 km (1.63 mi) on the planet Venus are coated with a shiny substance. Though the composition of this coat is not entirely certain, one theory is that Venus "snows" crystallized lead sulfide much as Earth snows frozen water. If this is the case, it would be the first time the substance was identified on a foreign planet. Other less likely candidates for Venus' "snow" are bismuth sulfide and tellurium. [2] A kilometre (American spelling: kilometer), symbol: km is a unit of length in the metric system equal to 1000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... A mile is any of a number of units of distance, each in the magnitude of 1–10 km. ... A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star. ... Adjective Venusian or (rarely) Cytherean (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ... For other uses, see Snow (disambiguation). ... Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ... General Name, Symbol, Number tellurium, Te, 52 Chemical series metalloids Group, Period, Block 16, 5, p Appearance silvery lustrous gray Atomic mass 127. ...

Physical properties

• Molecular weight: 239.28 g.mol^-1
• Density: 7700 kg.m^-3
• Melting Point 1390 K
• Dielectric constant: 200
• Energy gap: 0.41 eV
• Index of refraction: 3.9120

The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... Density (symbol: ρ - Greek: rho) is a measure of mass per unit of volume. ... The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. ... The metre, or meter, is a measure of length, approximately equal to 3. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... The dielectric constant εr (represented as or K in some cases) is defined as the ratio: where εs is the static permittivity of the material in question, and ε0 is the vacuum permittivity. ... In solid state physics and related applied fields, the band gap is the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. ... The electronvolt (symbol eV, or, rarely and incorrectly, ev) is a unit of energy. ... The refractive index of a material is the factor by which electromagnetic radiation is slowed down (relative to vacuum) when it travels inside the material. ...

See also

• infrared
• infra-red homing

Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of microwave radiation. ... Infra-red homing refers to a guidance system which uses the infra-red light emissions of a target to track it. ...

Related materials

• lead selenide
• lead telluride

Lead selenide (PbSe), or lead(II) selenide, a selenide of lead, is a semiconductor material. ... Lead telluride is a compound of lead and tellurium (PbTe); it is a narrow gap semiconductor. ...

References

• Lead Sulphide - An Intrinsic Semiconductor, E H Putley and J B Arthur, Proc. Phys. Soc. B, 64 pp. 616-618 (1951) DOI:10.1088/0370-1301/64/7/110
• Absorption Spectra of Lead Sulphide at Different Temperatures, W. Paui and R. V. Jones, Proc. Phys. Soc. B, 6 (3) pp. 194-200 (1953).
• Electronic and Vibrational Properties of Lead Sulphide Nanocrystals, Janet Lynn Machol, Ph.D. Thesis, Cornell Univ. (1993).
• Nonlinear optical properties of lead sulfide nanocrystals in polymeric coatings, S W Lu et al, Nanotechnology 13 669-673 (2002) DOI:10.1088/0957-4484/13/5/326

A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ... Reginald Victor Jones (September 28th, 1911-December 17th, 1997) was an English physicist and scientific intelligence expert. ... Cornell redirects here. ... A digital object identifier (or DOI) is a permanent identifier (permalink) given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. ...

External links

• Case Studies in Environmental Medicine (CSEM): Lead Toxicity
• ToxFAQs™: Lead
• National Pollutant Inventory - Lead and Lead Compounds Fact Sheet
• MSDS at Oxford university.