Zinc arsenide

Zinc arsenide (Zn₃As₂) is a binary compound of zinc with arsenic which forms gray tetragonal crystals. It is an inorganic semiconductor with a band gap of 1.0 eV.^[2]

Zinc arsenide

Names
Other names trizinc diarsenide
Identifiers
CAS Number	12006-40-5
3D model (JSmol)	Interactive image
ChemSpider	21242020 Y
ECHA InfoCard	100.031.338
EC Number	234-486-2
PubChem CID	25147458
CompTox Dashboard (EPA)	DTXSID00893156
InChI InChI=1S/2As.3Zn Key: RHKSESDHCKYTHI-UHFFFAOYSA-N
SMILES [Zn].[Zn]=[As].[Zn]=[As]
Properties
Chemical formula	Zn3As2
Molar mass	345.984 g/mol
Appearance	Silver grey[1]
Density	5.53 g/cm3[1]
Melting point	1,015 °C (1,859 °F; 1,288 K)
Solubility in water	Insoluble[1]
Structure
Crystal structure	Tetragonal
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H331, H350, H410
Precautionary statements	P201, P202, P222, P231+P232, P261, P264, P270, P271, P273, P280, P281, P301+P310+P330, P304+P340, P308+P313, P321, P370+P378, P391, P403+P233, P405, P422, P501
NFPA 704 (fire diamond)	4 0 0
Safety data sheet (SDS)	[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis and reactions

Zinc arsenide can be prepared by the reaction of zinc with arsenic

3 Zn + 2 As → Zn₃As₂

Structure

Zn₃As₂ has a room-temperature tetragonal form that converts to a different tetragonal phase at 190 °C and to a third phase at 651 °C.^[3] In the room-temperature form, the zinc atoms are tetrahedrally coordinated and the arsenic atoms are surrounded by six zinc atoms at the vertices of a distorted cube. The crystalline structure of zinc arsenide is very similar to that of cadmium arsenide (Cd₃As₂), zinc phosphide (Zn₃P₂) and cadmium phosphide (Cd₃P₂). These compounds of the Zn-Cd-P-As quaternary system exhibit full continuous solid-solution.^[4]

Electronic structure

Its lowest direct and indirect bandgaps are within 30 meV of each other.^[2]