The indium element has many useful properties, due to which it can be used in astronautics, technology, electronics, the nuclear industry and other industries. However, it is extremely difficult to find it in nature and to separate it from other substances. Because of this, he is listed in the list of rare elements. What properties does indium have? Is it metal or non-metal? Let's find out about all its features.
Item Discovery History
Indium was first discovered just 154 years ago. In part, this happened by accident, because his discoverers were looking for a completely different element. In 1863, chemists Theodor Richter and Ferdinand Reich tried to find thallium in the mineral sphalerite (zinc blende) , a new metal at that time, which was yet to be studied.
For their searches, 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. From the spectrum of this glow, you can find out what kind of element is in front of you.
In thallium, the color should be bright green, but instead, scientists discovered a blue glow. Not a single known element possessed such a spectrum, and chemists realized that luck smiled at them. Because of the peculiarities of the shade, they named their find in honor of the color of indigo. So a new metal was discovered - indium. And now in more detail about the features.
What kind of metal is this?
Indium is a light silver and very shiny metal resembling zinc. In the Periodic system, it belongs to the third group, stands at number 49 and is indicated by the symbol In.
In nature, it exists in the form of two isotopes: In 113 and In 115 . The latter is more common, but is radioactive. What is the period of metal indium 115? It breaks up in 6 · 10 14 years, turning into tin. There are also about 20 artificial isotopes that decay much faster. The largest "long-lived" among them has a half-life of 49 days.
Indium melts at a temperature of +156.5 ° C and boils at +2072 ° C. It is easily amenable to forging and other mechanical effects and could very 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 its chemical properties, it is similar to gallium or aluminum. It cannot form continuous solid compounds 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. In India, the metals that surround it in the Periodic system are easily dissolved, namely: thallium, tin, gallium, lead, bismuth, mercury, cadmium.
Some interesting facts about indium metal :
- Even with a long stay not in the air, it does not fade. This does not occur during the melting of metal.
- If you start to bend indium, then it will make a characteristic sound, like a creak or a crunch. It appears from the deformation of the crystal lattice of a substance.
- Indium burns at +800 ° C, while the flame is colored blue-violet, or indigo.
- This is the softest metal that you can hold in your hands. Only lithium is superior to 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.
Content in nature
Indium metal does not form independent deposits. It is very dispersed and in the form of nuggets is extremely rare. Among its own minerals are indium: sacuranite, roquesite, patrucite, jalindite. However, their rarity does not allow their use in industry.
A small amount of indium is found in sea and rain water, in oil, as well as in coal ash. Due to the similarity of ionic radii, indium is able to integrate into the crystal lattices of iron, magnesium, zinc, lead, manganese, tin, etc. Due to this, an insignificant amount is sometimes found with them.
As a rule, the indium content in minerals does not exceed 0.05-1%. Most metal is found in sphalerites and marmarites. Usually its concentration is the higher, the more zinc, iron and other metals already mentioned in them.
Metal price
Only a few years after the discovery, Indium was isolated in pure form. Due to the complexity of this process, one gram of indium was then valued at approximately $ 700. And although over a century and a half the methods for its preparation have improved significantly, it is still considered rare and expensive.
Today its average price is 600-800 dollars per kilogram and, surprisingly, it 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, indium brand IN-000 can be estimated 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 valuable material, in many countries it is used again.
Where to apply
Indium metal increases the wettability and corrosion resistance of the alloy. They are covered 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 melts at 46.5 ° C, which is why it is used for fire alarms.
Indium and tin oxide is used for semiconductors and various solders. In addition, it is used for the manufacture of computer monitors, television screens and tablets. In an alloy with silver or on its own, it is used for astronomical mirrors and mirrors of car headlights.
It is great 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 they have also learned to use it in medicine. It is used as a radioactive drug in the diagnosis of the liver, brain and lungs to detect tumors and other diseases.
Production methods
The majority of indium metal is mined from zinc and tin deposits. It is obtained from waste from the processing of polymetallic, tin, lead-zinc ores. The 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 "crude metal" then needs to be cleaned. This is done by refining by zone melting or other methods.
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, South Korea. However, the reserves of this element are very limited, it is assumed that they will run out within a few tens of years.