The history of magnets

The long history of magnets and the discovery of magnetism began with the first discovery of lodestones. It is not possible to name a real inventor of magnets, since there are naturally occurring materials with magnetic properties that were discovered rather than invented. The name magnet probably derives from early sites in the Magnesia region of Greece. The discovery of magnets is attributed in many mentions to Mr. Thales by Millet. According to legend, the Greek natural philosopher discovered the first magnet stones in 600 BC. He was always busy with his research and studied the forces of attraction between magnets and resin amber.

The black mineral made of iron and oxygen is called iron hydroxide and was formed naturally through volcanism. Today, over 9,600 sites have been identified.
The discovery of lodestones changed the whole world. Thanks to modern research and further investigations into magnetism in physics, magnets are now used in a wide variety of different areas. They are used in the following areas, for example:

● Hard drives
● Electric motors
● Computer monitors
● Televisions
● Microphones
● Speakers

The magnetic stones have now also found application in toys and jewelry.

Where were the first magnets used?

The natural lodestone is not a real stone, but rather a magnetized iron oxide. In the 3rd century BC, Chinese sources first mention the attractive phenomenon. The lodestone was often referred to as the loving stone. The people of China gave the stone this special name because it attracts iron like a loving mother attracts her children.

The oldest known use of magnetism in history is the compass.
In 200 BC, the Chinese used a compass that had a south-facing magnetite spoon. This showed all four directions. At that time, the original compass was probably used more in connection with Feng Shui for divination. It was mainly intended to determine the orientation of different buildings.

The compass in the form we know today was first mentioned in the first century AD, when a floating needle was used to determine cardinal directions. Finally, people discovered that magnets could also be used to magnetize other things. An iron needle held near a lodestone also acquires magnetic properties. You can then place the magnetic needle on the cork. As soon as you place the cork on a still water surface, the needle always turns in two specific directions - one side of the needle points south towards the South Pole, the other side towards the North Pole.

Pierre de Maricourt is considered the founder of the study of magnetism in physics. He was the first to systematically investigate magnetism and recorded the results of his investigation in writing on August 8, 1269. He made the following statements:

● identical magnetic poles repel each other
● breaking it creates two more magnets

The research and application in modern times

In 1600, scientific research brought further insights into the work of William Gilbert. In his work "De Magnete" he describes the earth as a large magnet. He discovered the analogy of the earth's magnetic field to the different magnets. Ultimately, thanks to this functionality, he was also able to explain the compass in detail. Although the use of the compass was already widespread, the Scottish physicist Mr. James Clerk Maxwell was the first to establish the connection between magnetism and electricity in 1864. The Maxwell equations he developed are still known today. They form the basis of the theory of electricity and magnetism. Since the 19th century, they have been among the most important achievements in physics and mathematics.

Further measurements such as those by Henry Gellibrand showed that the Earth's magnetic field is not static, but changes slowly from time to time.
In the early 19th century, the Magnetic Society was founded in Göttingen and Carl Friedrich Gauss succeeded in proving that the majority of the Earth's magnetic field comes from the Earth's interior.

Differentiation of different magnets

There are different types of magnets. Each has its own properties. The most well-known are:

● Ferrite magnet
● Neodymium magnet
● AINiCo magnet
● Samarium-cobalt magnet
● Electromagnets

Ferrite magnets

Most people have probably already held a ferrite magnet in their hands in the form of a refrigerator magnet.

Ferrite magnets can be recognized by their dark, black or anthracite color. Magnets made of hard ferrite are among the most widely used of all magnetic materials today. The actual raw materials are iron dioxide and strontium carbonate. Isotropic and anisotropic magnets can be made from hard ferrite. The anisotropic ferrite magnets have a significantly higher energy density than the isotropic magnets. This is more than 300 percent higher. Depending on the starting material, these can be divided into barium ferrite and coercive strontium ferrite.

The most important properties of ferrite permanent magnets include their excellent corrosion resistance and high functionality between -40 degrees Celsius and +250 degrees Celsius. They are also highly resistant to chemicals. In addition, they are non-toxic and environmentally friendly in terms of disposal in landfills. Ferrite magnets can be categorized in different ways:

Nowadays, permanent magnets are used in electrical engineering, the automotive and vehicle industries, as well as in medicine, mining and metallurgy. They also form the core of numerous pinboard magnets that are used in the office or for hobby purposes.

Neodymium magnets

Neodymium, or “Nd” for short, is one of the rare earth elements and was first extracted by Carl Auer von Welsbach at the end of the 18th century. Nevertheless, neodymium has a crucial and important property.
The discovery of neodymium goes back to Carl Friedrich Auer von Welsbach, Carl Gustav Mosander, Per Teodor Cleve and Lecoq de Boisbaudran. However, pure metallic neodymium was not produced until 1925.
In an alloy with boron and iron, neodymium forms the compound NdFeB – this material can be used to produce the strongest permanent magnets today. The neodymium magnet has significantly more energy than the steel magnet AlNiCo and is therefore used primarily where strong permanent magnets are required in the smallest possible volume.

Notable examples of this are:

● Generators
● Engines 
● Satellites

The classic neodymium magnets are designated with an "N" and a specific number, which indicates the respective magnetic strength. The values ​​are usually between N35 and N50. A disadvantage of NdFeB magnets is their enormous susceptibility to corrosion.

AlNiCo magnets

Basically, you can say that AlNiCo magnets are so-called permanent magnets. The steel magnet was developed in 1931. During the production process of these magnets, ferromagnetic metal pieces are magnetized by a strong magnetic field, which turns them into permanent magnets. Their magnetic force therefore lasts for decades.
The AlNiCo magnets are made of aluminum, cobalt and nickel. Depending on the material composition, they also contain iron, copper and titanium. Both isotropic and anisotropic magnets with different magnetic values ​​can be produced using different manufacturing processes. Permanent magnets of this type can only be processed using diamond tools.
The permanent magnets are particularly resistant to solvents; they are only resistant to acid concentrations of less than 10 percent. Inorganic acids such as citric acid or sea water damage the AlNiCo magnets. In addition, they have high remanence and excellent corrosion resistance. In addition, oils, organic solvents, alcohols and gasoline cannot harm them. The AlNiCo magnets can be disposed of in an environmentally friendly manner if necessary.

Samarium-cobalt magnets

Samarium cobalt is abbreviated to "SmCo" and was developed towards the end of the 1960s. It is an alloy of the rare earth metal samarium with the metal cobalt. The abbreviations for this are "Sm" and "Co". Samarium cobalt can be produced in two alloy structures - SMCo5 with no iron content and Sm2Co17 with an iron content of around 20 to 25 percent.

In the 1970s, samarium-cobalt was one of the materials with the highest known energy density. This continued until the discovery of neodymium-iron-boron. The powder metal samarium-cobalt is sintered under appropriate heat treatment conditions. This allows the full density and magnetic orientation to be achieved.

Due to the material composition, the magnets have an extremely strong magnetic field. In addition, they are particularly unlikely to demagnetize. The high corrosion resistance allows them to be heated to temperatures of up to 300 degrees Celsius. 

Electromagnets

Electromagnets differ fundamentally from permanent magnets because their magnetic field does not depend on magnetic material but is generated by the flow of current.

The discovery of electromagnetism in the 19th century by Hans Christian Oersted laid the foundation for the development of electromagnets.

The way electromagnets work is based on the fundamental connection between electricity and magnetism, known as electromagnetism. When an electric current flows through a coil of wire (winding), a magnetic field is created around the coil. The strength of this field depends on the current strength, the number of windings and the materials used. To increase the effect of the magnetic field, a core made of ferromagnetic material such as iron is often inserted into the coil. The key here are the so-called poles, which can be reversed depending on the direction of the current and thus control the way it works. Electromagnets are used today in numerous technologies, from precise control in industrial machines to everyday devices such as loudspeakers or door locks. They enable us to use the power of magnetism in a targeted and flexible way.

The big advantage of electromagnets over classic permanent magnets is that their magnetic field only remains active as long as the current is flowing. This means they can be switched on and off at will, making them ideal for applications such as electric motors, relays or industrial lifting magnets.