Tantalum carbides form a family of binary chemical compounds of tantalum and carbon with the empirical formula TaCx, where x usually varies between 0.4 and 1. They are extremely hard, brittle, refractory ceramic materials with metallic electrical conductivity. They appear as brown-gray powders, which are usually processed by sintering. Being important cermet materials, tantalum carbides are commercially used in tool bits for cutting applications and are sometimes added to tungsten carbide alloys. The melting points of tantalum carbides peak at about 3880 °C depending on the purity and measurement conditions; this value is among the highest for binary compounds. Only tantalum hafnium carbide may have a slightly higher melting point of about 3942 °C, whereas the melting point of hafnium carbide is comparable to that of TaC.
Cadmium telluride (CdTe) is a stable crystalline compound formed from cadmium and tellurium. It is mainly used as the semiconducting material in cadmium telluride photovoltaics and an infrared optical window. It is usually sandwiched with cadmium sulfide to form a p-n junction solar PV cell. Typically, CdTe PV cells use a n-i-p structure.
Tantalum(V) chloride, also known as tantalum pentachloride, is an inorganic compound with the formula TaCl5. It takes the form of a white powder and is commonly used as a starting material in tantalum chemistry.
It readily hydrolyzes to form tantalum(V) oxychloride (TaOCl3) and eventually tantalum pentoxide (Ta2O5); this requires that it be synthesised and manipulated under anhydrous conditions, using air-free techniques.
Zinc telluride is a binary chemical compound with the formula ZnTe. This solid is a semiconductor material with a direct band gap of 2.26 eV. It is usually a p-type semiconductor. Its crystal structure is cubic, like that for sphalerite and diamond.
Lead telluride is a compound of lead and tellurium (PbTe). It crystallizes in the NaCl crystal structure with Pb atoms occupying the cation and Te forming the anionic lattice. It is a narrow gap semiconductor with a band gap of 0.32 eV. It occurs naturally as the mineral altaite.
Tantalum pentoxide, also known as tantalum(V) oxide, is the inorganic compound with the formula Ta
2O
5. It is a white solid that is insoluble in all solvents but is attacked by strong bases and hydrofluoric acid. Ta
2O
5 is an inert material with a high refractive index and low absorption, which makes it useful for coatings. It is also extensively used in the production of capacitors, due to its high dielectric constant.
Silver telluride (Ag2Te) is a chemical compound, a telluride of silver, also known as disilver telluride or silver(I) telluride. It forms a monoclinic crystal. In a wider sense, silver telluride can be used to denote AgTe (silver(II) telluride, a metastable compound) or Ag5Te3.
Cadmium iodide, CdI2, is a chemical compound of cadmium and iodine. It is notable for its crystal structure, which is typical for compounds of the form MX2 with strong polarization effects.
Germanium telluride (GeTe) is a chemical compound of germanium and tellurium and is a component of chalcogenide glasses. It shows semimetallic conduction and ferroelectric behaviour.
Gallium(III) telluride (Ga2Te3) is a chemical compound classified as a metal telluride. At room temperature gallium(III) telluride is an odorless, black, brittle crystalline solid and is a semiconductor of the III-VI type that crystallizes in a lattice structure.
Gallium(II) telluride, GaTe, is a chemical compound of gallium and tellurium.
There is research interest in the structure and electronic properties of GaTe because of the possibility that it, or related compounds, may have applications in the electronics industry. Gallium telluride can be made by reacting the elements or by metal organic vapour deposition (MOCVD).
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GaTe produced from the elements has a monoclinic crystal structure. Each gallium atom is tetrahedrally coordinated by 3 tellurium and one gallium atom. The gallium-gallium bond length in the Ga2 unit is 2.43 Angstrom. The structure consists of layers and can be formulated as Ga24+ 2Te2−. The bonding within the layers is ionic-covalent and between the layers is predominantly van der Waals. GaTe is classified as a layered semiconductor (like GaSe and InSe which have similar structures). It is a direct band gap semiconductor with an energy of 1.65eV at room temperature.
A hexagonal form can be produced by low pressure metal organic vapour deposition (MOCVD) from alkyl gallium telluride cubane-type clusters e.g. from (t-butylGa( μ3-Te))4. The core consists of a cube of eight atoms, four gallium, and four tellurium atoms. Each gallium has an attached t-butyl group and three adjacent tellurium atoms and each tellurium has three adjacent gallium atoms. The hexagonal form, which is closely related to the monoclinic form, containing Ga24+ units, converts to the monoclinic form when annealed at 500 °C.
Tantalum(V) fluoride is the inorganic compound with the formula TaF5. It is one of the principal molecular compounds of tantalum. Characteristic of some other pentafluorides, the compound is volatile but exists as an oligomer in the solid state.
Tantalum borides are compounds of tantalum and boron most remarkable for their extreme hardness.
Coloradoite, also known as mercury telluride (HgTe), is a rare telluride ore associated with metallic deposit. Gold usually occurs within tellurides, such as coloradoite, as a high-finess native metal.
Tellurols are analogues of alcohols and phenols where tellurium replaces oxygen. Tellurols, selenols, and thiols have similar properties, but tellurols are the least stable. Although they are fundamental representatives of organotellurium compounds, tellurols are lightly studied because of their instability. Tellurol derivatives include telluroesters and tellurocyanates (RTeCN).
Tantalum(V) ethoxide is a metalorganic compound with formula Ta2(OC2H5)10, often abbreviated as Ta2(OEt)10. It is a colorless solid that dissolves in some organic solvents but hydrolyzes readily. It is used to prepare tantalum oxide films.
Ixiolite is an accessory oxide mineral found in granitic pegmatites. It is an oxide with the general chemical formula (Ta,Nb,Sn,Mn,Fe)4O8 or (Ta,Mn,Nb)O2.
Organotantalum chemistry is the chemistry of chemical compounds containing a carbon-to-tantalum chemical bond. A wide variety of compound have been reported, initially with cyclopentadienyl and CO ligands. Oxidation states vary from Ta(V) to Ta(-I).
