Arsenic Trisulfide (As2S3) Semiconductors

Topics Covered

Chemical Properties
Electrical Properties
Thermal, Mechanical and Optical Properties
Safety Information


Arsenic trisulfide is an inorganic compound with the chemical formula As2S3. It occurs naturally in the minerals orpiment and realgar. It is a group V/VI, intrinsic p-type semiconductor that exhibits photo-induced phase-change properties. It can be synthesized from the elements arsenic and sulfur, through aqueous precipitation and by reactions with oxygen.


Arsenic trisulfide finds applications in the following areas:

  • Pigment 
  • IR-transmitting glasses
  • Treatment of acute promyelocytic leukemia
  • Inorganic photoresists.

Chemical Properties

The chemical properties of arsenic trisulfide are provided in the table below:

Chemical Properties
Chemical Formula As2S3
Molecular Weight 246.04
CAS No. 1303-33-9
Group Arsenic – 15
Sulfur - 16
Crystal Structure Monoclinic
Lattice Constant a = 11.49 Å
b = 9.59 Å
c = 4.25 Å

Electrical Properties

The electrical properties of arsenic trisulfide are provided in the table below:

Electrical Properties
Magnetic Susceptibility -0.00007

Thermal, Mechanical and Optical Properties

The thermal, mechanical and optical properties of arsenic trisulfide are provided in the tables below:

Thermal Properties
Heat of Formation -169 kJ/mol
Standard molar entropy 163.6 J/mol K
Specific Heat Capacity 116.3 J/mol K
Mechanical Properties
Density 3.46 g/cm3
Melting Point 310°C
Boiling Point 707°C
Mohs Hardness 1.8
Optical Properties
Refractive Index 2.40

Safety Information

Safety Information
GHS Hazard Statements H301 - Toxic if swallowed
H331 - Toxic if inhaled
H410 - Very toxic to aquatic life with long lasting effects.
Safety Precautions P261 - Avoid breathing dust/ fume/ gas/ mist/ vapors/ spray
P273 - Avoid release to the environment
P301 + P310 - If swallowed, immediately call a poison center or doctor/physician
P311 - Call a poison center or doctor/ physician
P501 - Dispose of contents/ container to an approved waste disposal plant.

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