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About Indium

Indium Bohr

In 1863, chemists Ferdinand Reich and Hieronymous Theodor Richter were spectroscopically inspecting various ores in hope of finding the element thallium. Thallium’s characteristic green emission lines were absent, but they did note instead a bright blue spectral line. No element was known that produced such a line, so they correctly assumed that their samples contained a new element. They named the hypothetical new element indium from the indigo of its spectral line, and Richter went on to isolate pure indium metal the following year.

Indium took an exceedingly slow path from initial discovery to commercial relevance. For the first seventy years after its discovery, it was primarily a curiosity. A sample of the metal was presented at the World Fair in 1867, but no major indium mining operations existed until the late 1920’s. These operations were initiated only because several chemists became interested in using indium as a hardening surface treatment for ferrous metals and found that, in order to experiment with this idea, they had to develop a source of the metal themselves. The first large-scale application for the metal was as a coating for bearings in high-performance aircraft engines, but this and several niche alloys were the only sources of demand for the metal until it began to be used in semiconductor technologies starting in 1952. After this point, production gradually increased as applications for the metal both in alloys and in compound semiconductors continued to be developed.

Since 1992, a single semiconducting compound has accounted for the majority of demand for indium: indium tin oxide (ITO). When applied in a thin film to a surface, ITO produces an optically transparent conductive coating, allowing it to serve as a transparent electrode in electronic devices. Transparent electrodes are essential to the design of liquid crystal displays (LCDs), plasma screens, and touchscreen devices. ITO is also used to coat aircraft windshields, which can then be conveniently defrosted when a current is applied across the conducting film, and additionally is found in organic LEDs, solar cells, sodium vapor lamps, antistatic coatings, thin-film strain gauges, and electromagnetic interference shielding.

Though not used at the high volume of ITO, several other indium-based semiconductors have important applications. Most indium semiconductors, including indium arsenide, indium phosphide, indium nitride, indium antimonide, and many alloys of these with other semiconducting compounds, are notable for their high electron mobility, and are therefore found in high-frequency electronics such as high-frequency transistors. Additionally, these materials generally have direct bandgaps, making them suitable for optoelectronic devices such as LEDs, lasers, thin-film solar cells, radiation detectors, and integrated optical circuits. The compound semiconductor copper indium gallium selenide (CIGS) is one of only a few materials currently used commercially for the production of thin-film photovoltaic devices. Additionally, many indium semiconductors are being investigated for potential use in novel nanoengineered forms such as quantum dots and nanowires.

Outside of use in semiconductors, indium is found primarily as a metal, either alone or in alloys, usually in applications that exploit its low melting point. Indium can be used to produce alloys such as Galistan, which are liquid at room temperature and can replace mercury in applications such as thermometers. Indium alloys are used frequently in seals found in low-temperature applications, as they maintain malleability and ductility at low temperatures. Indium-containing solders are have become more important thanks to increasingly stringent restrictions on the use of lead, another low-melting-point metal once found in most low-temperature solders. Additionally, indium may be found in die casting alloys and in thermal interface materials.

Two niche uses of indium are also notable. A radioisotope of indium is used in indium leukocyte imaging, which is used to track white blood cells in the body in order to identify sites of infection. Indium is also a component of control rods used in nuclear reactors, where it absorbs excess neutrons along with silver and cadmium .

Indium is not particularly rare--it is approximately as abundant as mercury--but there are no economically significant indium ore minerals. The metal must therefore be extracted from other metal ores where it occurs in trace amounts, and today is most commonly extracted from byproducts of zinc mining. Increasingly, indium is recovered from waste material produced by the ITO sputtering process, and even directly from scrap LCD panels. These recycling efforts vary in economic feasibility depending on the efficiency of the process and current prices of the metal, and therefore their use varies widely between countries and from year to year. Concerns about depleting world indium resources have led to substantial interest in developing alternative transparent electrode materials to substitute for ITO in electronics.

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High Purity (99.999%) Indium Oxide (In2O3) Powder Indium is available as metal and compounds with purities from 99% to 99.9999% (ACS grade to ultra-high purity); metals in the form of foil, sputtering target, and rod, and compounds as submicron and nanopowder. High Purity (99.99999%) Indium (In) Sputtering TargetIndium is also used in various metal alloys (See AE Alloys). Elemental or metallic forms include pellets, wire and granules for evaporation source material purposes. Indium oxide is available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Indium 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. Indium is available in soluble forms including chlorides, nitrates and acetates. These compounds are also manufactured as solutions at specified stoichiometries.

Indium Properties

Indium (In) atomic and molecular weight, atomic number and elemental symbol Indium is a Block P, Group 13, Period 5 element. Indium Bohr ModelThe number of electrons in each of Indium's shells is 2, 8, 18, 18, 3 and its electronic configuration is [Kr] 4d10 5s2 5p1. In its elemental form, CAS 7440-74-6, Indium has a silvery lustrous gray appearance. The indium atom has a radius of and its Van der Waals radius is Indium has found application in semiconductor devices and other electronic applications. It is used in making bearing alloys, germanium transistors, rectifiers, and photoconductors. Elemental IndiumIndium is used to make low-melting alloys. Indium can be plated onto metal and evaporated onto glass, forming a mirror that performs as well as those made with silver and which better resists atmospheric corrosion. Indium information, including technical data, safety data, high purity properties, research, applications and other useful facts are discussed below. Scientific facts such as the atomic structure, ionization energy, abundance on earth, conductivity and thermal properties are also included.

Symbol: In
Atomic Number: 49
Atomic Weight: 114.82
Element Category: post-transition metal
Group, Period, Block: 13, 5, p
Color: silvery lustrous gray/ silvery-white
Other Names: N/A
Melting Point: 156.5985 °C, 313.8773 °F, 429.7485 K
Boiling Point: 2072 °C, 3762 °F, 2345 K
Density: 7.31 g·cm3;at 20 °C
Liquid Density @ Melting Point: 7.02 g·cm2345 K
Density @ 20°C: 7.31 g/cm2345 K
Density of Solid: 7310 kg·m3
Specific Heat: 234 @25C ( J K-1 kg-1 )
Superconductivity Temperature: 3.41 [or -269.74 °C (-453.53 °F)] K
Triple Point: 429.7445 K, -1 kPa
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 3.27
Heat of Vaporization (kJ·mol-1): 231.8
Heat of Atomization (kJ·mol-1): 243.72
Thermal Conductivity: 81.8 W·m?1·K?1
Thermal Expansion: (25 °C) 32.1 µm·m-1·K-1
Electrical Resistivity: (20 °C) 83.7 nΩ·m
Tensile Strength: 7.99 tons/in.2
Molar Heat Capacity: 26.74 J·mol-1·K-1
Young's Modulus: 11 GPa
Shear Modulus: N/A
Bulk Modulus: <10
Poisson Ratio: 0.4498
Mohs Hardness: 1.2
Vickers Hardness: <10
Brinell Hardness: 8.83 MPa
Speed of Sound: (20 °C) 1215 m·s-1
Pauling Electronegativity: 1.78
Sanderson Electronegativity: 2.14
Allred Rochow Electronegativity: 1.49
Mulliken-Jaffe Electronegativity: 1.76 (sp2 orbital)
Allen Electronegativity: 1.656
Pauling Electropositivity: 2.22
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 49
Protons: 49
Neutrons: 64
Electron Configuration: [Kr] 4d10 5s2 5p1
Atomic Radius: 167 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 142±5 pm
Covalent Radius (Å): 1.42
Van der Waals Radius:
Oxidation States: 3, 2, 1 (amphoteric oxide)
Phase: Solid
Crystal Structure: tetragonal
Magnetic Ordering: diamagnetic
Electron Affinity (kJ·mol-1) 28.935
1st Ionization Energy: 558.30 kJ·mol-1
2nd Ionization Energy: 1820.67 kJ·mol-1
3rd Ionization Energy: 2704.50 kJ·mol-1
CAS Number: 7440-74-6
EC Number: 231-180-0
MDL Number: MFCD00134048
Beilstein Number: N/A
SMILES Identifier: [In]
InChI Identifier: InChI=1S/In
PubChem CID: 5359967
ChemSpider ID: 4514408
Earth - Total: 2.14 ppb
Mercury - Total: 0.024 ppb
Venus - Total: 2.24 ppb
Earth - Seawater (Oceans), ppb by weight: 0.0001
Earth - Seawater (Oceans), ppb by atoms: 0.000005
Earth -  Crust (Crustal Rocks), ppb by weight: 160
Earth -  Crust (Crustal Rocks), ppb by atoms: 30
Sun - Total, ppb by weight: 4
Sun - Total, ppb by atoms: 0.04
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 45
Meterorite (Carbonaceous), ppb by atoms: 10
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 0.3
Universe, ppb by atom: 0.003
Discovered By: Ferdinand Reich and Hieronymous Theodor Richter
Discovery Date: 1863
First Isolation: Hieronymous Theodor Richter (1867)

Health, Safety & Transportation Information for Indium

Indium is only slightly toxic. Safety data for Indium metal, nanoparticles 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 indium material or compound referenced in the Products tab. The below information applies to elemental (metallic) Indium.

Safety Data
Signal Word Warning
Hazard Statements H302-H312-H315-H319-H332-H335
Hazard Codes Xn
Risk Codes 20/21/22-36/37/38
Safety Precautions 26-36
RTECS Number NL1050000
Transport Information N/A
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Exclamation Mark-Acute Toxicity
Review and Print SDS for Indium Metal


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


Product Name: Indium Metal

Product Number: All applicable American Elements product codes, e.g. IN-M-02, IN-M-03, IN-M-04, IN-M-05, IN-M-06, IN-M-07

CAS #: 7440-74-6

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.
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:
7440-74-6 Indium
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:
Indium oxide
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.
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:
Do not store together with acids.
Store away from oxidizing agents.
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:
7440-74-6 Indium (100.0%)
REL (USA) Long-term value: 0.1 mg/m³
as In
TLV (USA) Long-term value: 0.1 mg/m³
as In
EL (Canada) Long-term value: 0.1 mg/m³
EV (Canada) Long-term value: 0.1 mg/m³
as indium
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
Color: Silvery-white
Odor: Odorless
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 156.6 °C (314 °F)
Boiling point/Boiling range: 2072 °C (3762 °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: Not determined.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 20 °C (68 °F): 0 hPa
Density at 20 °C (68 °F): 7.31 g/cm³ (61.002 lbs/gal)
Relative density
Not determined.
Vapor density
Not applicable.
Evaporation rate
Not applicable.
Solubility in / Miscibility with Water: Insoluble
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
Reacts with strong oxidizing agents
Conditions to avoid
No further relevant information available.
Incompatible materials:
Oxidizing agents
Hazardous decomposition products:
Metal oxide fume
Indium oxide


Information on toxicological effects
Acute toxicity:
No effects known.
LD/LC50 values that are relevant for classification:
No data
Skin irritation or corrosion:
May cause irritation
Eye irritation or corrosion:
May cause irritation
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.
Carcinogenic categories
OSHA-Ca (Occupational Safety & Health Administration)
Substance is not listed


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:
Marine Pollutant (DOT):


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.
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.

Indium Isotopes

Indium has two naturally occuring isotopes: 113In and 115In. The stable isotope, 113In, accounts for only 4.3% of naturally occurring indium. 115In has a half life of 441 trillion years and accounts for 95.7% of naturally occurring indium.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
97In 96.94954(64)# 5# ms Unknown 9/2+# N/A 776.17 -
98In 97.94214(21)# 45(23) ms [32(+32-11) ms] ß+ to 98Cd 0+# N/A 790.77 -
99In 98.93422(43)# 3.1(8) s [3.0(+8-7) s] ß+ to 99Cd 9/2+# N/A 806.3 -
100In 99.93111(27) 5.9(2) s ß+ to 100Cd; ß+ + p to 99Ag (6,7)+ N/A 817.17 -
101In 100.92634(32)# 15.1(3) s ß+ to 101Cd; ß+ + p to 100Ag 9/2+# N/A 835.5 -
102In 101.92409(12) 23.3(1) s ß+ to 102Cd; ß+ + p to 101Ag (6+) N/A 843.58 -
103In 102.919914(27) 60(1) s ß+ to 103Cd 9/2+# N/A 860.97 -
104In 103.91830(9) 1.80(3) min ß+ to 104Cd 5,6(+) N/A 869.05 -
105In 104.914674(19) 5.07(7) min ß+ to 105Cd 9/2+ N/A 877.13 -
106In 105.913465(13) 6.2(1) min ß+ to 106Cd 7+ N/A 885.21 -
107In 106.910295(12) 32.4(3) min ß+ to 107Cd 9/2+ N/A 893.29 -
108In 107.909698(10) 58.0(12) min ß+ to 108Cd 7+ N/A 910.68 -
109In 108.907151(6) 4.2(1) h EC to 109Cd 9/2+ 5.54 918.76 -
110In 109.907165(13) 4.9(1) h EC to 110Cd 7+ 4.37 926.84 -
111In 110.905103(5) 2.8047(5) d EC to 111Cd 9/2+ 5.5 934.92 -
112In 111.905532(6) 14.97(10) min EC to 112Cd; ß- to 112Sn 1+ 2.82 943 -
113In 112.904058(3) STABLE - 9/2+ 5.5289 951.08 4.29
114In 113.904914(3) 71.9(1) s EC to 114Cd; ß- to 114Sn 1+ 2.82 959.15 -
115In 114.903878(5) 4.41(25)E+14 y ß- to 115Sn 9/2+ 5.5408 967.23 95.71
116In 115.905260(5) 14.10(3) s ß- to 116Sn; EC to 116Cd 1+ N/A 975.31 -
117In 116.904514(6) 43.2(3) min ß- to 117Sn 9/2+ N/A 983.39 -
118In 117.906354(9) 5.0(5) s ß- to 118Sn 1+ N/A 991.47 -
119In 118.905845(8) 2.4(1) min ß- to 119Sn 9/2+ N/A 999.55 -
120In 119.90796(4) 3.08(8) s ß- to 120Sn 1+ N/A 1007.63 -
121In 120.907846(29) 23.1(6) s ß- to 121Sn 9/2+ N/A 1015.71 -
122In 121.91028(5) 1.5(3) s ß- to 122Sn 1+ N/A 1014.47 -
123In 122.910438(26) 6.17(5) s ß- to 123Sn (9/2)+ N/A 1022.55 -
124In 123.91318(5) 3.11(10) s ß- to 124Sn 3+ N/A 1030.63 -
125In 124.91360(3) 2.36(4) s ß- to 125Sn 9/2+ N/A 1038.7 -
126In 125.91646(4) 1.53(1) s ß- to 126Sn 3(+#) N/A 1046.78 -
127In 126.91735(4) 1.09(1) s ß- to 127Sn; ß- + n to 126Sn 9/2(+) N/A 1054.86 -
128In 127.92017(5) 0.84(6) s ß- to 128Sn; ß- + n to 127Sn (3)+ N/A 1053.62 -
129In 128.92170(5) 611(4) ms ß- to 129Sn; ß- + n to 128Sn 9/2+# N/A 1061.7 -
130In 129.92497(4) 0.29(2) s ß- to 130Sn; ß- + n to 129Sn 1(-) N/A 1069.78 -
131In 130.92685(3) 0.28(3) s ß- to 131Sn; ß- + n to 130Sn (9/2+) N/A 1077.86 -
132In 131.93299(7) 206(4) ms ß- to 132Sn; ß- + n to 131Sn (7-) N/A 1076.62 -
133In 132.93781(32)# 165(3) ms ß- + n to 132Sn; ß- to 133Sn (9/2+) N/A 1084.7 -
134In 133.94415(43)# 140(4) ms ß- to 134Sn; ß- + n to 133Sn; ß- + 2n to 132Sn N/A N/A 1083.46 -
135In 134.94933(54)# 92(10) ms Unknown 9/2+# N/A 1091.54 -