General Description
A toxic corrosive light yellow liquid or gas. Boiling point 67°F. Melting point 37°F. Noncombustible. Used in the manufacture of other chemicals and in the manufacture of electronics.
Reactivity Profile
TUNGSTEN HEXAFLUORIDE(7783-82-6) emits very toxic and irritating fumes containing metallic tungsten and tungsten fluorides when heated to decomposition. Reacts violently with tetramethoxysilane [Jacob, E., Angew. Chem., 1982, 21, p. 143].
Air & Water Reactions
Decomposes in water giving hydrofluoric acid, another corrosive material.
Health Hazard
TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Vapors are extremely irritating and corrosive. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.
Potential Exposure
A strong halogenating agent. Used to
apply tungsten coatings to other surfaces by vapor deposition
process; making electronics and components; in the
manufacture of other chemicals.
Fire Hazard
Some may burn but none ignite readily. Vapors from liquefied gas are initially heavier than air and spread along ground. Some of these materials may react violently with water. Cylinders exposed to fire may vent and release toxic and/or corrosive gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately. If
this chemical has been inhaled, remove from exposure, begin
rescue breathing (using universal precautions, including
resuscitation mask) if breathing has stopped and CPR if heart
action has stopped. Transfer promptly to a medical facility.
When this chemical has been swallowed, get medical attention.
Give large quantities of water and induce vomiting. Do
not make an unconscious person vomit. Medical observation
is recommended for 24-48 hours after breathing overexposure,
as pulmonary edema may be delayed. As first aid for
pulmonary edema, a doctor or authorized paramedic may
consider administering a drug or other inhalation therapy. If
frostbite has occurred, seek medical attention immediately;
do NOT rub the affected areas or flush them with water. In
order to prevent further tissue damage, do NOT attempt to
remove frozen clothing from frostbitten areas. If frostbite has
NOT occurred, immediately and thoroughly wash contaminated
skin with soap and water.
Shipping
UN2196 Tungsten hexafluoride, Hazard Class:
2.3; Labels: 2.3-Poisonous gas, 8-Corrosive material,
Inhalation Hazard Zone B. Cylinders must be transported
in a secure upright position, in a well-ventilated truck.
Protect cylinder and labels from physical damage. The
owner of the compressed gas cylinder is the only entity
allowed by federal law (49CFR) to transport and refill
them. It is a violation of transportation regulations to refill
compressed gas cylinders without the express written permission
of the owner.
Incompatibilities
Decomposes on contact with water and
moist air, forming highly corrosive hydrofluoric acid.
Violent reaction on contact with methyl silicate.
Description
Tungsten(VI) fluoride, also known as tungsten hexafluoride, WF6, is a toxic, corrosive, colorless gas, with a density of
about 13 g/L (roughly 11 times heavier than air). It is one of the densest gases known under standard conditions. WF6 is
frequently used by the semiconductor industry to form tungsten films, through CVD. The WF6 molecule is octahedral with
the symmetry point group of Oh. The W-F bond distances are 183.2 pm. Between 2.3℃ and 17℃, tungsten hexafluoride
condenses into a pale-yellow liquid with a density of 3.44 g/cm3 at 15℃. At 2.3℃ it freezes into a white solid with a cubic
crystalline structure, with lattice constant of 628 pm and a calculated density of 3.99 g/cm3
. At 29℃ this structure converts to an orthorhombic solid with lattice constants of a = 960.3 pm, b = 871.3 pm, and c = 504.4 pm and a density of
4.56 g/cm3
. In this phase, the W-F distance is 181 pm, and the mean closest intermolecular contacts are 312 pm.
Chemical Properties
Colorless gas or light-yellow liquid.
Chemical Properties
Tungsten hexafluoride is a toxic, colorless gas
or a light yellow liquid.
Waste Disposal
Return refillable compressed
gas cylinders to supplier. Nonrefillable cylinders should be
disposed of in accordance with local, state and federal regulations.
Allow remaining gas to vent slowly into atmosphere
in an unconfined area or exhaust hood. Refillabletype
cylinders should be returned to original supplier with
any valve caps and outlet plugs secured and valve protection
caps in place.
Uses
In the electronics industry as a source of tungsten metal that connects the aluminum layers within semiconductor devices.
Synthesis
WF6 is usually produced by the exothermic reaction of F2 gas with tungsten powder between 350℃ and 400℃.
W +3F2→WF6
