Cadmium phosphide

Cadmium phosphide (Cd₃P₂) is an inorganic chemical compound. It is a grey or white bluish solid semiconductor material with a bandgap of 0.5 eV.^[1] It has applications as a pesticide, material for laser diodes and for high-power-high-frequency electronics.^[1]

Cadmium phosphide

Names
Other names Tricadmium diphosphide
Identifiers
CAS Number	12014-28-7
3D model (JSmol)	Interactive image
ChemSpider	140173
ECHA InfoCard	100.031.437
EC Number	234-595-5
PubChem CID	159393
CompTox Dashboard (EPA)	DTXSID401010274
InChI InChI=1S/3Cd. 2P/q3*+2;2*-3 Key: BYWFNUBYQJKAKF-UHFFFAOYSA-N
SMILES [Cd+2].[Cd+2].[Cd+2].[P-3].[P-3]
Properties
Chemical formula	Cd3P2
Molar mass	399.178 g/mol
Appearance	bluish white[1] or gray[2]
Density	5.96 g/cm3[1]
Melting point	700[1] °C (1,292 °F; 973 K)
Electron mobility	1500 cm2/Vs[1]
Refractive index (nD)	3.88[1]
Structure
Crystal structure	Tetragonal
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H312, H314, H332, H350, H370, H410
Precautionary statements	P201, P202, P210, P233, P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P340, P308+P313, P312, P330, P362+P364, P391, P405, P501
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

Cadmium phosphide can be prepared by the reaction of cadmium with phosphorus:

6 Cd + P₄ → 2 Cd₃P₂

Structure

Cd₃P₂ has a room-temperature tetragonal form.

The crystalline structure of cadmium phosphide is very similar to that of zinc phosphide (Zn₃P₂), cadmium arsenide (Cd₃As₂) and zinc arsenide (Zn₃As₂). These compounds of the Zn-Cd-P-As quaternary system exhibit full continuous solid-solution.^[3]

Applications

Over the last decade, interest in cadmium phosphide as a source for fast, near-IR emission has grown due to the development of cadmium phosphide quantum dots. Literature has demonstrated that these quantum dots possess tunable emission between 700 nm to 1500 nm.^[4][5] A recent paper investigated the effect of surface passivation on these quantum dots and showed that cadmium phosphide quantum dots may have an intrinsic band-edge relaxation time less than 100 ns.^[6]

Safety

Like other metal phosphides, it is acutely toxic when swallowed due to the formation of phosphine gas when it reacts with gastric acid. It is also carcinogen and dangerous for the skin, eyes and other organs in a large part due to cadmium poisoning.