Is Cobalt Magnetic - Enze Mfg Co. Ltd.

Cobalt is a magnetic metal that exhibits ferromagnetic properties, meaning it is strongly attracted to magnetic fields. Unlike most transition metals, which typically display paramagnetic properties resulting in a weak attraction, cobalt is unique due to unpaired electrons, making it magnetic.

Table of Contents

What is Cobalt?

Cobalt metal is labeled by the symbol “Co” and has an atomic number of 27 in the periodic table. It is located in the d block, along with nickel and copper. Cobalt is found in ores combined with other chemical elements such as nickel (Ni) and copper (Cu). Metallic cobalt is obtained through reduction smelting, primarily as a coproduct of copper and nickel mining. The primary cobalt sources are found in the copper belts of Namibia and Congo.

Cobalt metal is a weak reducing agent. There is a stable layer of oxide on its surface, which prevents it from reacting with water. At room temperature, cobalt metal reacts slowly with inorganic acids. It does not directly react with nitrogen and hydrogen but becomes highly reactive with sulfur, phosphorus, and carbon at higher temperatures.

History

The element cobalt was initially discovered in 1735 by a Swedish chemist named Georg Brandt. Prior to this discovery, cobalt was found in Egyptian statues and Persian neck beads as a cobalt luster in 3rd millennium glass, often in combination with copper. Brandt first observed the presence of a blue color, which was attributed to another metal, cobalt. It was named “Kobold” in the 16th century. At that time, Brandt found that the blue element was not bismuth but rather a poisonous arsenic-containing cobalt ore.

Appearance

The appearance of cobalt metal is a bluish-silvery cobalt luster. It is a non-ductile metal with high hardness. Cobalt shares similar physical properties with nickel and iron. Similar to them, it is also a permanent magnet and can be attracted by magnetic fields. It is used to make solid magnets and with nickel and aluminum to make magnetic alloys.

Cobalt, ₂₇Co

Properties

Cobalt metal possesses unique physical and chemical properties. It has a bluish-silvery appearance, and it is brittle and very hard. The electron configuration of cobalt is [Ar] 3d7 4s2, and it has 3 unpaired electrons in its orbital, which accounts for its strong magnetic properties, making it a permanent magnet. Additionally, it has a high melting point, making it suitable for high-temperature applications. Cobalt metal has the following basic properties:

Atomic mass: 83.2g
Boiling point: 2927°C
Melting point: 1495°C
Curie temperature: 1,115°C (2,039°F)
Density: 8.9g/cm3 (20°C)

Naturally Magnetic Material

Ferromagnetic materials exhibit unique behavior when subjected to a magnetic field. Ferromagnetism is characterized by:

Magnetic permeability
High attraction to magnets
Ability to become permanent magnets
Easy to induce magnetism

Cobalt is a naturally occurring ferromagnetic material, which means it is naturally magnetic. Within cobalt, there are atomic dipoles aligned in the same direction. As a result, even in the absence of any magnetic field, cobalt domains have a net magnetic moment.

Remember that the magnetic moment in adjacent domains may face different directions within cobalt, potentially canceling out the total magnetic moment. However, a small magnetic field can easily align them to create permanent magnets.

Additionally, the above phenomenon is attributed to the unique arrangement of electrons in cobalt. In cobalt’s d orbital, there are 3 unpaired electrons, which contribute to its magnetic properties.

Why Is Cobalt Magnetic?

Cobalt, like iron, possesses unique magnetic properties due to its 3 unpaired electrons. These electrons play a significant role in cobalt’s magnetic behavior more than any other transition metal in the periodic table. Cobalt generates its own magnetic field and retains it even when an external field is removed. When an external magnetic field approaches cobalt, the valence electrons begin to align in the direction of the magnetic field. Magnetic domains are responsible for creating a magnetic effect within a material. This property is specific to ferromagnetic metals, making them the most suitable choice for permanent magnets in various magnetic applications. Cobalt magnets are known for their high strength and power, which is advantageous for magnetic applications.

Cobalt Structure vs. Magnetism

Naturally, cobalt exists in two main crystallographic structures, namely:

Face-centered cubic (FCC) structure
Hexagonal close-packed (HCP) structure

The structures and electron configuration of cobalt contribute to its magnetism. Even in its pure form, cobalt exhibits a strong magnetic moment due to its unique alignment, resulting in ferromagnetism. If you’re curious about what ferromagnetism is, here are some general properties you can expect from cobalt and other ferromagnetic materials:

Permanent dipole moments exist within the domains.
Large magnetic susceptibility.
An external magnetic field determines the orientation of atomic dipoles.
Large magnetic flux density and relative permeability.
Strongly attracted by the magnetic field.
The degree of magnetization is significant and directly proportional to the magnetizing field.
Their magnetic properties depend on temperature. Ferromagnetic materials transition to paramagnetic above the Curie point.

Magnetic Properties of Cobalt

Cobalt is a ferromagnetic metal. Like other metals in this category, cobalt has three unpaired electrons in its outer shell.

When exposed to a magnetic field, the unpaired electrons align in the same direction by spinning. This spinning creates magnetic dipoles.

When the unpaired electrons align in the same direction as an external magnetic field, both magnetic fields fuse, allowing the atom’s field to stretch beyond the atom itself. This results in a pull toward a stronger magnetic field.

As a ferromagnetic material, cobalt can retain its magnetism. Like other ferromagnetic materials, cobalt can remain magnetic even after the external magnet has been removed when exposed to the external magnetic field.

Cobalt has a magnetic permeability of 2.3×10−2. Magnetic permeability refers to the rate of magnetization gained by a metal after exposure to an external magnetic field. Thanks to the presence of three unpaired electrons, which is higher than in most metals, and the way these electrons interact, cobalt has an increased Curie temperature of 1145 °C.

Factors Affecting Cobalt Magnetism

Purity: The level of cobalt purity can impact its magnetism. Higher-purity cobalt demonstrates increased magnetism than impure cobalt, while magnetism is reduced in alloyed states.
Temperature: The magnetic properties of cobalt are significantly influenced by temperature. Temperature changes can affect how cobalt behaves in terms of its magnetic properties. At high temperatures, cobalt loses its magnetism and becomes less magnetic. This implies that cold cobalt is generally considered stronger regarding its magnetic power.
External Magnetic Fields: The presence of cobalt in a solid material can cause it to become magnetized or demagnetized depending on the strength and direction of an external magnetic field of a certain intensity.
Crystalline Structure: In terms of cobalt’s magnetic behavior, its crystalline structure is crucial. Modulating magnetic properties through variations in crystal structure can lead to different magnetic strengths.
Alloying Elements: Cobalt is a metal that can exhibit modified magnetic properties when combined with other metals such as iron or nickel. Alloying agents not only influence the magnetic strength of cobalt but also its behavior within a magnetic field.

Applications of Cobalt

Cobalt-chromium and nickel-cobalt alloys are derived from metallic cobalt. These alloys find applications in the aerospace industry and the production of aircraft, turbine, and engine components.
It is used in the manufacture of lithium-ion batteries.
As it is a permanent magnet, it can be utilized to produce both soft and hard magnets, depending on the uses. It is also utilized to produce rare-earth magnets.
Adding cobalt luster enables the production of blue-colored glass, pottery, paints, and ceramics, enhancing their aesthetic appeal.
Cobalt catalysts play a crucial role in the chemical and petroleum industries.
Cobalt-60 is an artificial radioactive isotope with a long lifespan used to produce gamma rays.
Cobalt isotopes are also utilized for inspecting materials and products.

Can Cobalt Become a Magnet?

Cobalt is a ferromagnetic metal; therefore, it can retain its magnetism after exposure to an external magnetic field.

Once the unpaired electrons align in the same direction, they retain a magnetic charge, allowing them to attract magnetic metals and be attracted by other magnets easily.

Another method of creating a permanent magnet from cobalt involves alloying it with nickel and aluminum.

The alloy of these three metals creates a permanent magnet known as Alnico.

Summary

Cobalt is a popular material in the manufacturing process of magnets due to its reliability and superior magnetic properties.

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