Indium metal: description, properties and applications

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The element indium has many useful properties, thanks to which it can be used in space exploration, engineering, electronics, nuclear industry and other industries. However, it is extremely difficult to find it in nature and separate it from other substances. Because of this, it is listed as a rare element. What are the properties of indium? Is it metal or non-metal? Let's find out about all its features.

Element discovery history

Indium was first discovered only 154 years ago. In part, this happened by chance, because its discoverers were looking for a completely different element. In 1863, chemists Theodor Richter and Ferdinand Reich tried to detect thallium in the mineral sphalerite (zinc blende), a new metal at that time that had yet to be studied.

For their search they used the spectral analysis of Kirchhoff and Bunsen. The essence of the method is that when heated to high temperatures, the atoms of the elements begin to emit light corresponding to a specific frequency range. By the spectrum of this glow, you can find out what kind of element is in front of you.

Thallium should have a bright green color, but scientists have found a blue glow instead. No known element had such a spectrum, and chemists realized thatthey were lucky. Due to the peculiarities of the shade, they named their find after the indigo color. And so a new metal, indium, was discovered. And now in more detail about the features.

What is this metal?

Indium is a light silvery and very shiny metal, reminiscent of zinc. In the Periodic system, it belongs to the third group, stands at number 49 and is denoted by the symbol In.

It exists in nature as two isotopes: In¹¹³ and In¹¹⁵. The latter is more common, but is radioactive. What is the period of the metal indium 115? It decays in 6·10^{14 years, turning into tin. There are also about 20 artificial isotopes that decay much faster. The longest-lived among them has a half-life of 49 days.}

Indium melts at +156.5 °C and boils at +2072 °C. It lends itself easily to forging and other mechanical effects and could well be used in jewelry. However, due to its high softness, it quickly deforms. Metal can be easily bent, cut with a knife and even scratched with a fingernail.

Chemical properties

In terms of its chemical properties, it is similar to gallium or aluminum. It cannot form continuous solid bonds with any metal. It does not react at all with alkali solutions. At certain temperatures, it reacts with iodine, selenium, sulfur and its dioxide, reacts with chlorine and bromine. Metals that surround it in the Periodic Table easily dissolve in indium, namely:thallium, tin, gallium, lead, bismuth, mercury, cadmium.

Some interesting facts about the metal of India:

• Even with a long stay in the air, it does not fade. This does not happen when the metal is melted either.
• If you start bending indium, it will make a characteristic sound, similar to a creak or crunch. It appears from the deformation of the crystal lattice of matter.
• Indium burns at +800 °C, the flame is blue-violet, or indigo.
• This is the softest metal you can hold in your hands. Only lithium surpasses it, but it is too active and immediately oxidizes in air, forming a poisonous alkali.
• The alloy of indium with gallium is very fusible and becomes liquid already at +16 °C.

Contained in nature

Metal indium does not form independent deposits. It is very scattered and extremely rare in the form of nuggets. Indium's own minerals include sakuranite, roquesite, patrukite, and jalindite. However, their rarity prevents them from being used in industry.

A small amount of indium is found in sea and rain water, in oil, and also in the ashes of coal. Due to the similarity of ionic radii, indium is able to integrate into the crystal lattices of iron, magnesium, zinc, lead, magnesium, tin, etc. Due to this, a small amount of it is sometimes found along with them.

As a rule, the content of indium in minerals does not exceed 0.05-1%. Most of the metal is found in sphalerite and marmarite. Usually itthe concentration is higher, the more zinc, iron and other metals already mentioned in them.

Metal price

Indium was isolated in its pure form just a few years after the discovery. Due to the complexity of this process, one gram of indium was then valued at about $700. And although methods for obtaining it have improved significantly over a century and a half, it is still considered rare and expensive.

Today, its average price is 600-800 dollars per kilogram and, surprisingly, does not fall much with an increase in its production. The purity of the metal is usually indicated in its marking: IN-2, IN-1, IN-0, IN-00, IN-000, IN-00000. The more zeros, the better and more expensive it is. For example, IN-000 grade indium can be valued at about $2,000 per kilogram.

The high cost of indium metal is explained by its low content in nature and high demand. 600-800 tons are mined per year, which absolutely does not cover all the needs for it. Due to its unique properties, it is much better and more durable than other, cheaper metals. In order not to lose such a valuable material, in many countries it is reused.

Where apply

Metal indium increases the wettability and corrosion resistance of the alloy. They are coated with lead-silver bearings, which are used in aviation and automotive technology. It is also capable of lowering the melting point of other metals. So, its mixture with tin, lead, cadmium and bismuth meltsat 46.5°C, making it suitable for fire alarms.

Indium tin oxide is used for semiconductors and various solders. In addition, it is used for the manufacture of computer monitors, TV screens and tablets. Alloyed with silver or alone, it is used for astronomical mirrors and car headlight mirrors.

It is excellent for creating photocells, phosphors, thermoelectric materials, seals in space technology. Indium absorbs neutrons well and can be used in nuclear reactors.

Nothing is known about the biological role of this element in our body, but it has also been used in medicine. It is used as a radioactive drug in the diagnosis of the liver, brain and lungs to detect tumors and other diseases.

Methods of obtaining

The main amount of indium metal is mined from zinc and tin deposits. It is obtained from waste from the processing of polymetallic, tin, lead-zinc ores. Separation and purification of indium is carried out in several stages.

First, it is precipitated by adjusting the acidity level of the solution. The resulting "black metal" then needs to be cleaned. They do this by refining by zone melting or in other ways.

Today one of the main producers of India is Canada. In addition to it, large volumes of metal are mined by the USA, China, Japan, and South Korea. However, stocksof this element are very limited, it is expected that they will run out within a few decades.