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About Iridium

Iridium Bohr

Platinum first came to Europe in the form of platina, grey metallic crumbs that were unusable to metalworkers in their native form. When platina is dissolved in aqua regia, a mixture of strong acids, a dark insoluble residue is left behind. An English chemist named Smithson Tennant was the first to experiment extensively on large quantities of this residue, eventually convincing himself and announcing to the world in 1804 that it contained two new elements: osmium and iridium. While osmium was named for the pungent odor produced by its oxide, iridium was notable for the many vibrant colors of its salts, leading Tennant to derive its name from Iris, the Greek goddess of rainbows.

All of the platinum group metals are known for being hard, fairly non-reactive, and performing well under high-temperatures, but iridium stands out in these regards even within this small family. It is the most corrosion-resistant of all metals, is extremely hard, and has an extremely high melting temperature--2466 degrees Celsius. While iridium metal’s resistance to change is extremely desirable in some applications, the tradeoff is that solid iridium is too hard and brittle to work or machine and melts at too high a temperature to make traditional casting practical.

The limited options for techniques to work with iridium significantly limit applications of the pure metal, but the one of the few that exist drives much of the demand for the element. The primary use of pure iridium is in crucibles for procedures that must be carried out under extremely high-temperatures. Most notably, these crucibles are essential for the production of many high-purity single-crystal materials, including semiconductors, garnets used in lasers and industrial welding, synthetic sapphire for electronics applications, silicate crystals used in sensors, and lithium crystals used in electronics.

Other uses of pure iridium include encapsulation of the plutonium-238 fuel in radioisotope thermoelectric generators of unmanned spacecraft, the production of antiprotons for particle physics experiments, and the production of mirrors used in x-ray optics applications. Additionally, radioisotopes of iridium are used for gamma-radiography for testing of metals, as well as for some forms of medical radiotherapy.

Most other applications of iridium use it combination with other elements. In alloys, it imparts increased hardness and resistance to corrosion and heat. These alloys are used in a range of applications where the material chosen must withstand substantial wear from use or extreme environmental conditions. Historically, iridium alloys were sought after for fountain pen tips and components of cannons that suffered from significant wear, while modern uses include electrical contacts for spark plugs, microelectrodes for use in electrophysiology, and extremely resilient aircraft engine parts. A platinum-iridium alloy was also used to construct the international prototype meter and kilogram mass in 1889, and the kilogram prototype is still in use as the international standard for mass. Iridium compounds are frequently used in research and industry as chemical catalysts.

Like other platinum group metals, iridium is typically obtained for commercial use as a byproduct from nickel and copper mining and processing, but can also be obtained from ores rich in platinum and from alluvial deposits.

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High Purity (99.999%) Iridium Oxide (IrO2) Powder Iridium is alloyed with platinum to produce highly corrosion resistant electrical contacts for spark plugs. Iridium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). High Purity (99.999%) Iridium (Ir)Sputtering TargetElemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Iridium nanoparticles and nanopowders are also available. Iridium oxide is available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Iridium fluoride is another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Iridium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Iridium Properties

Iridium(Ir) atomic and molecular weight, atomic number and elemental symbolIridium is a Block D, Group 9, Period 6 element. The number of electrons in each of iridium's shells is 2, 8, 18, 32, 15, 2 and its electron configuration is [Xe] 4f14 5d7 6s2. Elemental IridiumThe iridium atom has a radius of and its Van der Waals radius is Iridium Bohr ModelIn its elemental form, CAS 7439-88-5, Iridium has a silvery white appearance. Iridium is a member of the platinum group of metals. It is the most corrosion resistant metal known and is the second-most dense element (after osmium). It will not react with any acid and can only be attacked by certain molten salts, such as molten sodium chloride. Iridium metal is found alone and in alloys with other platinum group metals. Iridium was first discovered by Smithson Tennant in 1803. Iridium's name is derived from the Greek goddess Iris, personification of the rainbow, on account of the striking and diverse colors of its salts.

Symbol: Ir
Atomic Number: 77
Atomic Weight: 192.217
Element Category: transition metal
Group, Period, Block: 9, 6, d
Color: silvery white/ silvery-white
Other Names: Iridio
Melting Point: 2466 °C, 4471 °F, 2739 K
Boiling Point: 4428 °C, 8002 °F, 4701 K
Density: 22.56 g/cm3
Liquid Density @ Melting Point: 19 g/cm3
Density @ 20°C: 22.56 g/cm3
Density of Solid: 22650 kg·m3
Specific Heat: 0.13 (kJ/kg K)
Superconductivity Temperature: 0.11 [or -273.04 °C (-459.47 °F)] K
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 26.4
Heat of Vaporization (kJ·mol-1): 612.1
Heat of Atomization (kJ·mol-1): 664.34
Thermal Conductivity: 147 W·m-1·K-1
Thermal Expansion: 6.4 µm/(m·K)
Electrical Resistivity: (20 °C) 47.1 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 25.10 J·mol-1·K-1
Young's Modulus: 528 GPa
Shear Modulus: 210 GPa
Bulk Modulus: 320 GPa
Poisson Ratio: 0.26
Mohs Hardness: 6.5
Vickers Hardness: 1760 MPa
Brinell Hardness: 1670 MPa
Speed of Sound: (20 °C) 4825 m·s-1
Pauling Electronegativity: 2.2
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.55
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 1.8
Reflectivity (%): 78
Refractive Index: N/A
Electrons: 77
Protons: 77
Neutrons: 115
Electron Configuration: [Xe] 4f14 5d7 6s2
Atomic Radius: 136 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 141±6 pm
Covalent Radius (Å): 1.32
Van der Waals Radius: 202 pm
Oxidation States: 3,1, 0, 1, 2, 3, 4, 5, 6
Phase: Solid
Crystal Structure: face-centered cubic
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 111.537
1st Ionization Energy: 880 kJ·mol-1
2nd Ionization Energy: 1600 kJ·mol-1
3rd Ionization Energy: N/A
CAS Number: 7439-88-5
EC Number: 231-095-9
MDL Number: MFCD00011062
Beilstein Number: N/A
SMILES Identifier: [Ir]
InChI Identifier: InChI=1S/Ir
PubChem CID: 23924
ChemSpider ID: 22367
Earth - Total: 840 ppb
Mercury - Total: 650 ppb 
Venus - Total: 890 ppb
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: 0.4
Earth -  Crust (Crustal Rocks), ppb by atoms: 0.05
Sun - Total, ppb by weight: 2
Sun - Total, ppb by atoms: 0.01
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 550
Meterorite (Carbonaceous), ppb by atoms: 60
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 2
Universe, ppb by atom: 0.01
Discovered By: Smithson Tennant
Discovery Date: 1803
First Isolation: Smithson Tennant (1803)

Health, Safety & Transportation Information for Iridium

Iridium is only slightly toxic in its elemental form; however, safety data for Iridium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Iridium.

Safety Data
Signal Word Danger
Hazard Statements H228-H319
Hazard Codes F,Xi
Risk Codes 11-36
Safety Precautions 16-26
RTECS Number N/A
Transport Information UN 3089 4.1/PG 2
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Exclamation Mark-Acute Toxicity
Review and Print SDS for Iridium Metal


Date Created: 05/15/2015
Date Revised: 05/15/2015


Product Name: Iridium Metal

Product Number: All applicable American Elements product codes, e.g. IR-M-02, IR-M-03, IR-M-04, IR-M-05

CAS #: 7439-88-5

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887


Classification of the substance or mixture
Classification according to Regulation (EC) No 1272/2008
The substance is not classified as hazardous to health or the environment according to the CLP regulation.
Classification according to Directive 67/548/EEC or Directive 1999/45/EC
Not applicable
Information concerning particular hazards for human and environment:
No information known.
Hazards not otherwise classified
No information known.
Label elements
Labelling according to Regulation (EC) No 1272/2008
Not applicable
Hazard pictograms
Not applicable
Signal word
Not applicable
Hazard statements
Not applicable
WHMIS classification
Not controlled
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)

Health (acute effects) = 0
Flammability = 0
Physical Hazard = 0
Other hazards
Results of PBT and vPvB assessment
Not applicable.
Not applicable.


Chemical characterization: Substances
CAS# Description:
7439-88-5 Iridium
Identification number(s):
EC number:


Description of first aid measures
General information
No special measures required.
After inhalation
Seek medical treatment in case of complaints.
After skin contact
Generally the product does not irritate the skin.
After eye contact
Rinse opened eye for several minutes under running water. If symptoms persist, consult a doctor.
After swallowing
If symptoms persist consult doctor.
Information for doctor
Most important symptoms and effects, both acute and delayed
No further relevant information available.
Indication of any immediate medical attention and special treatment needed
No further relevant information available.


Extinguishing media
Suitable extinguishing agents
Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents
Special hazards arising from the substance or mixture
If this product is involved in a fire, the following can be released:
Metal oxide fume
Advice for firefighters
Protective equipment:
No special measures required.


Personal precautions, protective equipment and emergency procedures
Not required.
Environmental precautions:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow product to reach sewage system or any water course.
Do not allow to penetrate the ground/soil.
Methods and material for containment and cleaning up:
Pick up mechanically.
Prevention of secondary hazards:
No special measures required.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.


Precautions for safe handling
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Information about protection against explosions and fires:
No special measures required.
Conditions for safe storage, including any incompatibilities
Requirements to be met by storerooms and receptacles:
No special requirements.
Information about storage in one common storage facility:
Not required.
Further information about storage conditions:
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
Specific end use(s)
No further relevant information available.


Additional information about design of technical systems:
No further data; see section 7.
Control parameters
Components with limit values that require monitoring at the workplace:
The product does not contain any relevant quantities of materials with critical values
that have to be monitored at the workplace.
Additional information:
No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Maintain an ergonomically appropriate working environment.
Breathing equipment:
Not required.
Protection of hands:
Not required.
Penetration time of glove material (in minutes)
Not determined
Eye protection:
Safety glasses
Body protection:
Protective work clothing.


Information on basic physical and chemical properties
General Information
Form: Solid in various forms
Odor: Not determined
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 2450 °C (4442 °F)
Boiling point/Boiling range: 4428 °C (8002 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous)
Not determined.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Not determined.
Danger of explosion: Product does not present an explosion hazard.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure: Not applicable.
Density at 20 °C (68 °F): 22.65 g/cm³ (189.014 lbs/gal)
Relative density
Not determined.
Vapor density
Not applicable.
Evaporation rate
Not applicable.
Solubility in / Miscibility with Water: Not determined
Partition coefficient (n-octanol/water): Not determined.
dynamic: Not applicable.
kinematic: Not applicable.
Other information
No further relevant information available.


No information known.
Chemical stability
Stable under recommended storage conditions.
Thermal decomposition / conditions to be avoided:
Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions
No dangerous reactions known
Conditions to avoid
No further relevant information available.
Incompatible materials:
No information known.
Hazardous decomposition products:
Metal oxide fume


Information on toxicological effects
Acute toxicity:
No effects known.
LD/LC50 values that are relevant for classification:
No data
Skin irritation or corrosion:
Powder: irritant effect
Eye irritation or corrosion:
Powder: irritant effect
No sensitizing effects known.
Germ cell mutagenicity:
No effects known.
No classification data on carcinogenic properties of this material is available from the EPA, IARC, NTP, OSHA or ACGIH.
Reproductive toxicity:
No effects known.
Specific target organ system toxicity - repeated exposure:
No effects known.
Specific target organ system toxicity - single exposure:
No effects known.
Aspiration hazard:
No effects known.
Subacute to chronic toxicity:
No effects known.
Additional toxicological information:
To the best of our knowledge the acute and chronic toxicity of this substance is not fully known.


Aquatic toxicity:
No further relevant information available.
Persistence and degradability
No further relevant information available.
Bioaccumulative potential
No further relevant information available.
Mobility in soil
No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow undiluted product or large quantities to reach ground water, water course or sewage system.
Avoid transfer into the environment.
Results of PBT and vPvB assessment
Not applicable.
Not applicable.
Other adverse effects
No further relevant information available.


Waste treatment methods
Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Disposal must be made according to official regulations.


Not applicable
UN proper shipping name
Not applicable
Transport hazard class(es)
Not applicable
Packing group
Not applicable
Environmental hazards: Not applicable.
Special precautions for user
Not applicable.
Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code
Not applicable.
Transport/Additional information: DOT
Marine Pollutant (DOT): No


Safety, health and environmental regulations/legislation specific for the substance or mixture
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Domestic Substances List (DSL).
SARA Section 313 (specific toxic chemical listings)
Substance is not listed.
California Proposition 65
Prop 65 - Chemicals known to cause cancer
Substance is not listed.
Prop 65 - Developmental toxicity
Substance is not listed.
Prop 65 - Developmental toxicity, female
Substance is not listed.
Prop 65 - Developmental toxicity, male
Substance is not listed.
Information about limitation of use:
For use only by technically qualified individuals.
Other regulations, limitations and prohibitive regulations
Substance of Very High Concern (SVHC) according to the REACH Regulations (EC) No. 1907/2006.
Substance is not listed.
The conditions of restrictions according to Article 67 and Annex XVII of the Regulation (EC) No 1907/2006 (REACH) for the manufacturing, placing on the market and use must be observed.
Substance is not listed.
Annex XIV of the REACH Regulations (requiring Authorisation for use)
Substance is not listed.
REACH - Pre-registered substances
Substance is listed.
Chemical safety assessment:
A Chemical Safety Assessment has not been carried out.


Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

Iridium Isotopes

There are two natural isotopes of iridium (Ir): 191Ir and 193Ir.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
164Ir 163.99220(44)# 1# ms Unknown 2-# N/A 1247.83 -
165Ir 164.98752(23)# <1# µs p to 164Os 1/2+# N/A 1265.22 -
166Ir 165.98582(22)# 10.5(22) ms a to 161Re; p to 164Os (2-) N/A 1273.3 -
167Ir 166.981665(20) 35.2(20) ms a to 163Re; p to 166Os; ß+ to 197Os 1/2+ N/A 1281.38 -
168Ir 167.97988(16)# 161(21) ms a to 164Re; ß+ to 168Os high N/A 1298.77 -
169Ir 168.976295(28) 780(360) ms [0.64(+46-24) s] a to 166Re; ß+ to 169Os 1/2+# N/A 1306.85 -
170Ir 169.97497(11)# 910(150) ms [0.87(+18-12) s] ß+ to 170Os; a to 166Re low# N/A 1314.93 -
171Ir 170.97163(4) 3.6(10) s [3.2(+13-7) s] a to 171Re; ß+ to 167Os 1/2+# N/A 1323.01 -
172Ir 171.97046(11)# 4.4(3) s ß+ to 172Os; a to 168Re (3+) N/A 1331.09 -
173Ir 172.967502(15) 9.0(8) s ß+ to 173Os; a to 169Re (3/2+,5/2+) N/A 1348.48 -
174Ir 173.966861(30) 7.9(6) s ß+ to 174Os; a to 170Re (3+) N/A 1356.56 -
175Ir 174.964113(21) 9(2) s ß+ to 175Os; a to 171Re (5/2-) N/A 1364.64 -
176Ir 175.963649(22) 8.3(6) s ß+ to 176Os; a to 172Re N/A N/A 1372.72 -
177Ir 176.961302(21) 30(2) s ß+ to 177Os; a to 173Re 5/2- N/A 1380.8 -
178Ir 177.961082(21) 12(2) s ß+ to 178Os N/A N/A 1388.88 -
179Ir 178.959122(12) 79(1) s ß+ to 179Os (5/2)- N/A 1406.27 -
180Ir 179.959229(23) 1.5(1) min ß+ to 180Os (4,5)(+#) N/A 1414.35 -
181Ir 180.957625(28) 4.90(15) min ß+ to 181Os (5/2)- N/A 1422.43 -
182Ir 181.958076(23) 15(1) min ß+ to 182Os (3+) N/A 1430.51 -
183Ir 182.956846(27) 57(4) min ß+ to 183Os; a to 179Re 5/2- N/A 1438.59 -
184Ir 183.95748(3) 3.09(3) h ß+ to 184Os 5- N/A 1446.66 -
185Ir 184.95670(3) 14.4(1) h ß+ to 185Os 5/2- N/A 1454.74 -
186Ir 185.957946(18) 16.64(3) h ß+ to 186Os 5+ N/A 1462.82 -
187Ir 186.957363(7) 10.5(3) h ß+ to 187Os 3/2+ N/A 1470.9 -
188Ir 187.958853(8) 41.5(5) h EC to 188Os 1- 0.3 1478.98 -
189Ir 188.958719(14) 13.2(1) d EC to 189Os 3/2+ 0.13 1487.06 -
190Ir 189.9605460(18) 11.78(10) d EC to 190Os 4- 0.04 1485.82 -
191Ir 190.9605940(18) Observationally Stable - 3/2+ 0.1462 1493.9 37.3
192Ir 191.9626050(18) 73.827(13) d ß- to 192Pt 4+ 1.92 1501.98 -
193Ir 192.9629264(18) Observationally Stable - 3/2+ 0.1592 1510.06 62.7
194Ir 193.9650784(18) 19.28(13) h ß- to 194Pt 1- N/A 1518.14 -
195Ir 194.9659796(18) 2.5(2) h ß- to 195Pt 3/2+ N/A 1526.21 -
196Ir 195.96840(4) 52(1) s ß- to 196Pt (0-) N/A 1534.29 -
197Ir 196.969653(22) 5.8(5) min ß- to 197Pt 3/2+ N/A 1542.37 -
198Ir 197.97228(21)# 8(1) s ß- to 198Pt N/A N/A 1541.13 -
199Ir 198.97380(4) 20# s ß- to 199Pt 3/2+# N/A 1549.21 -