Material Safety Data Sheet (MSDS): Tungsten Diselenide

Identification

Product Name: Tungsten Diselenide
Chemical Formula: WSe₂
CAS Number: 12067-46-8
Synonyms: Tungsten diselenide, Tungsten(IV) selenide
Recommended Use: Research, electronic materials, optical applications
Supplier Details: Company name, address, emergency contact, phone number available on request

Hazard Identification

GHS Classification: Not classified as hazardous under GHS guidelines
Signal Word: None
Hazard Statements: Dust may cause irritation to respiratory system, eyes, and skin
Pictograms: None required
Precautionary Statements: Avoid breathing dust, wash thoroughly after handling, wear protective equipment
Other Hazards: Not identified as carcinogenic, mutagenic, or toxic for reproduction under current evaluation

Composition / Information on Ingredients

Chemical Name: Tungsten Diselenide
Common Name: WSe₂
Concentration: 100%
CAS Number: 12067-46-8
Impurities/Additives: No known impurities significantly affecting classification

First Aid Measures

Inhalation: Move to fresh air. Support breathing as needed. Seek medical attention for persistent irritation or symptoms.
Skin Contact: Wash with soap and water. Remove contaminated clothing; launder before reuse. Get medical advice if irritation occurs.
Eye Contact: Rinse cautiously with water for several minutes, lifting eyelids. If irritation persists, seek professional attention.
Ingestion: Rinse mouth. Do not induce vomiting. Get medical help if feeling unwell or symptoms develop.
Most Important Symptoms/Effects: Respiratory, eye or skin irritation due to particulate exposure

Fire-Fighting Measures

Suitable Extinguishing Media: Use dry chemical, CO₂, or foam. Avoid using water as this material is not water soluble.
Special Hazards: High temperature may release toxic selenium oxides or tungsten fumes; dust can form explosive mixtures with air
Advice for Firefighters: Wear self-contained breathing apparatus. Use full protective gear. Cool surrounding containers with water spray if exposed to fire.
Combustion Products: Possible release of tungsten oxides, selenium oxides, and other sulfur or metal-oxide fumes in extreme heat conditions

Accidental Release Measures

Personal Precautions: Use proper personal protection. Avoid dust generation. Ventilate area.
Environmental Precautions: Prevent material from entering watercourses or drains.
Methods for Cleaning Up: Sweep or vacuum spilled material without dispersing dust. Place in suitable containers for disposal. Clean contamination zone thoroughly.
Reference to Other Sections: Consult protective measures listed in Sections 8 and 13

Handling and Storage

Safe Handling: Avoid generation of dust. Do not breathe dust or get into eyes or on skin. Use appropriate personal protective equipment. Keep away from incompatible materials like oxidizing agents.
Storage Conditions: Keep in tightly sealed container. Store in cool, dry, and well-ventilated area. Maintain away from food, drink, and animal feed.
Material Incompatibilities: Oxidizing agents, strong acids
Special Requirements: No smoking, eating or drinking in work area. Wash hands after use.

Exposure Controls and Personal Protection

Occupational Exposure Limits: No national exposure limit for tungsten diselenide established. Tungsten compounds TWA (OSHA PEL): 5 mg/m³ (respirable), Selenium compounds TWA (OSHA PEL): 0.2 mg/m³
Engineering Controls: Use local exhaust ventilation or other engineering controls to keep airborne levels low.
Personal Protection: Wear tightly fitting safety goggles, gloves (nitrile or PVC), and protective clothing. Use approved respirator during dust-generating operations.
Hygiene Measures: Wash hands before breaks and at end of work. Avoid contact with skin, eyes, and clothing. Remove contaminated clothing for cleaning.

Physical and Chemical Properties

Appearance: Grey to black powder or crystalline solid
Odor: Odorless
Odor Threshold: Not applicable
pH: Insoluble in water
Melting Point: ~1025°C
Boiling Point: Not applicable (sublimes at ~1350°C)
Flash Point: Not flammable
Evaporation Rate: Not applicable
Flammability: Not classified as flammable
Vapor Pressure: Negligible at ambient conditions
Vapor Density: Not applicable
Density: 9.32 g/cm³ at 25°C
Solubility: Insoluble in water, soluble in strong acids
Partition Coefficient: Not determined
Auto-Ignition Temperature: Not self-igniting
Decomposition Temperature: Above 500°C (selenium oxides formation)
Viscosity: Not applicable

Stability and Reactivity

Chemical Stability: Stable under recommended storage and normal use.
Reactivity: Unreactive at room temperature. Dust can be explosive with air in some cases.
Hazardous Reactions: Reacts with strong oxidizers and acids, forming toxic gases.
Conditions to Avoid: Heat, open flames, incompatible materials, dust accumulation
Incompatible Materials: Oxidizing agents, strong acids
Hazardous Decomposition Products: Tungsten oxides, selenium oxides, and other metal or nonmetal oxides if thermally decomposed

Toxicological Information

Acute Toxicity: Not well studied; evidence suggests low oral and dermal toxicity. Dust inhalation may irritate respiratory tract.
Skin Corrosion/Irritation: May cause slight irritation on prolonged or repeated contact.
Serious Eye Damage/Irritation: Dust contact may cause irritation or redness.
Respiratory or Skin Sensitization: No data suggesting sensitization effects.
Long-term Effects: Chronic inhalation of selenium compounds linked to respiratory symptoms; no specific data for WSe₂.
Carcinogenicity/Mutagenicity: Material not listed as human carcinogen or mutagen by NTP, IARC, OSHA.
Inhalation LC50 / Oral LD50: Data not available for complex compound; component toxicity data may not directly apply.
Other Information: Prolonged exposure to high levels of inorganic selenium may cause selenosis—rare in workplace environments with adequate controls.

Ecological Information

Toxicity to Aquatic Life: Data inadequate; insoluble in water, limited immediate hazard to aquatic organisms expected.
Persistence and Degradability: Inorganic compound, not readily degradable.
Bioaccumulative Potential: Low solubility limits bioaccumulation, but selenium can accumulate in some organisms.
Mobility in Soil: Low mobility in typical environmental conditions.
Other Adverse Effects: Selenium is an essential trace element but toxic to organisms at elevated concentrations. Proper handling required to prevent environmental release.

Disposal Considerations

Waste Disposal Methods: Dispose of product/containers according to local, national, and international regulations. Do not release into the environment.
Contaminated Packaging: Dispose as unused product.
Special Precautions: Contact licensed waste disposal provider. Use a sealed, labeled container. Avoid dust generation during disposal.
EU Waste Code: Non-hazardous waste classification probable but verify with local guidelines.

Transport Information

UN Number: Not regulated for transport
UN Proper Shipping Name: Not regulated
Transport Hazard Class: None
Packing Group: None
Environmental Hazards: Not considered marine pollutant
Special Precaution for Users: Secure packaging to prevent dust release. Handle in accordance with good industrial hygiene and safety practices.
Transport in Bulk: Not applicable

Regulatory Information

Safety, Health and Environmental Regulations: Substance not specifically listed on major chemical inventories as hazardous. No REACH pre-registration required. Not subject to TSCA restrictions in pure form.
Workplace Safety: Observe occupational exposure limits for tungsten and selenium compounds.
SARA 302/304: No components subject to reporting
SARA 313: Selenium compounds listed; check for regulatory actions depending on composition and use.
California Prop 65: Not listed
Other Regulatory Information: Observe all country, regional and local regulations regarding use, handling, and disposal.