Draft:Aluminum telluride

Aluminum telluride is an inorganic chemical compound of aluminium and tellurium with the chemical formula Al2Te3.

Preparation
Aluminum telluride can be obtained by direct combination of elemental aluminum with tellurium at 1000&#x20;&#xB0;&#x43;&#x20;.



Properties
Aluminum telluride is a dark grey to black solid. It has a band gap of 2.4 eV. The compound decomposes in humid air. .

In its pure (very air-sensitive) form, it occurs in at least two phases. The orange-red low-temperature (α) modification transforms into the yellow high-temperature (β) form at 720 °C. The conversion from β- to α-Al2Te3, which is associated with such a small enthalpy change that it cannot be observed with differential thermal analysis, takes place after prolonged annealing just below the conversion point. The α form crystallizes in the monoclinic crystal system with the lattice constants a = 13.885 Å, b = 7.189 Å, c = 4.246 Å, p = 90.21° and an additional superstructure. The β form has a monoclinic crystal structure with space group P21/c (space group no. 14)Template:Space group/14 and the lattice constants a = 7.181(1) Å, b = 12.848(3) Å, c = 14.167(3) Å, b= 90.04(2)°. This form represents a separate structure type. The tellurium atoms form a hexagonal dense packing parallel to the (001) plane, one third of the tetrahedral vacancies are occupied by aluminum atoms, whereby the tetrahedral vacancies are occupied in such a way that a layered structure is formed. Some sources also report another form of the defect wurtzite type.

Uses
Aluminum telluride is used in the semiconductor industry. It can also be used to produce hydrogen telluride by the following reaction with hydrogen chloride.