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Does Diamond Conduct Electricity? (And Heat?)

Does Diamond Conduct Electricity? (And Heat?)

Most people say a girl’s best friends are diamonds. Diamonds are used in various industries and the stunning jewelry they produce. Do you know its many properties in addition to the numerous applications? Does a diamond, for instance, conduct electricity?

In this article, we will answer that question. Along with talking about diamonds’ conductivity, we’ll also explore whether or not diamonds can be doped to conduct electricity. We will address questions like do diamonds conduct heat, burn, melt, or conduct electricity when molten?

Read: Does Concrete Conduct Electricity?

Are Diamonds Conductive?

Diamonds do not conduct electricity because they do not have any delocalized free electrons in the outer shell of the carbon atom. Though diamond does not conduct electricity, it is a good thermal conductor. Diamond stops conducting when no free ions are left to carry the electric charge. Any material can conduct electricity thanks to the movement of electrons.

There are two types of conductivity: Electrical and thermal conductivity. A material’s capacity to carry electricity is referred to as electrical conductivity. The capacity of a material to conduct heat is known as thermal conductivity.

Each electron in a diamond is linked to four strong covalent bonds. Diamond stops conducting when no free ions are left to carry the electric charge. Any material can conduct electricity thanks to the movement of electrons. Free electrons carry the charge of an electric current. Since they are not connected to any other atoms, the outer electrons of free atoms are in charge of carrying and transferring the electrical charge.

The free electrons in a conductive medium will collide with other free electrons when a battery adds an electrical charge to it. The free electrons will continue to bump into other free electrons, passing along their electric charge and causing an electrical current to flow.

Why Does Diamond Not Conduct Electricity?

When it comes to heat, diamond is conductive, but not when it comes to electricity. Only carbon atoms, which join with other carbon atoms through covalent bonds, make up a pure diamond. The diamond has four electrons in its outer shell. In a diamond, each carbon atom’s electron forms a covalent link with another electron. Hence no free electrons to carry an electric charge. 

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With every electron now bonded, there is no free electron. Due to a lack of free electrons to carry electric current, a diamond cannot conduct electricity. The essential requirement for electrical conductivity to occur is the presence of free electrons. Electrons are charge carriers; they carry the charge current when they flow. 

When a material like a diamond lacks free electrons, it lacks the capability for electric current to flow through. 

Read: Does Plastic Conduct Electricity?

Why Does Graphite Conduct Electricity but Not Diamond?

Allotropes of carbon include graphite and diamond. However, graphite conducts electricity, whereas diamond does not. The existence of delocalized pi-bond electrons above and below the sheets of carbon atoms in graphite is what facilitates conductivity. In graphite, the carbon atoms arrange themselves in a hexagonal pattern. One electron is free because the other three available electrons form covalent bonds with the other carbon atoms.

The free electrons from all the carbon atoms can freely travel between the graphene molecules. On the other hand, diamond has no unoccupied outer shell electrons since they are all actively involved in forming covalent bonds with the other carbon atoms.

Although carbon appears to be the same element in diamond and graphite, the physical properties of the two elements differ. Their structure and the unique ways their carbon atoms link account for most of the differences.

Because graphite has high electrical conductivity, it is perfect for creating several electronic products, including solar panels, batteries, and electrodes.

Learn more on why graphite conducts electricity whereas diamond does not: 

Can a Diamond Be Doped to Conduct Electricity?

Diamonds can have their physical characteristics artificially changed to conduct electricity. When you add boron to the diamond, it slightly alters the structure of the diamond to conduct electricity. The boron impurities create a hole in the valence electron shells of the diamond.  As a result of the holes, the diamond becomes an excellent conductor of electricity and can carry an electric current.

However, since the natural blue diamond is already a superior electrical conductor, it doesn’t need to be doped. The blue color is caused by boron impurities rather than an artificial process. The boron impurities are in charge of the electrical conductivity of the diamond.

Because synthetic diamonds have a promising future as semiconductors, phosphorous and boron impurities are added to them.

Some of the uses of doped diamonds are: 

  • Phosphorous-doped diamond films
  • Ultraviolet emitting diodes

Does Diamond Conduct Heat?

Surprisingly, diamond is a good conductor of heat but poor at conducting electricity. Diamonds lack the free electrons necessary to conduct heat well. However, they have bound electrons in their tetrahedral structure, making it easy for energy to be transferred between covalent bonds. Heat transfer is the outcome of the energy produced.

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Unlike other elements where free electrons’ vibration transfers heat, diamonds’ heat is transferred through Lattice Vibrations. These vibrations take place within the solid covalent bonds connecting carbon atoms. Everything makes sense when you realize thermal conductivity is the movement of energy and electrical conductivity is the flow of free electrons.

However, this does not imply that the movement of electrons does not aid heat transfer. Although it improves thermal conduction, the free flow of electrons is not essential for heat transmission.

diamonds

Does Diamond Conduct Electricity When Molten?

Molten state diamond conducts electricity. Diamond ultimately begins to melt when heated. Diamond will change depending on how it is melted, though. Diamond becomes graphite when heated in the absence of oxygen. The entire structure of a diamond and some of its properties change when it transforms into graphite. Free electrons in graphite are electrically charged.

Molten substances, like molten diamonds, have free ions that can move freely and conduct electricity. Because the ions in solid diamonds are fixed and unable to move, electrical current cannot flow through them. But that changes when the diamond melts.

Any material that can carry electrical current must have some free electrons capable of doing so. The electrons’ looser bonds improve the flow of electricity to their atoms. A diamond becomes a liquid when heated in the presence of oxygen.

Does Diamond Burn?

It is possible to burn a diamond with a hot torch and liquid oxygen. Diamond will burn at 1652°F(900°C). Diamond consists of pure carbon, and carbon burns quickly. When you first heat a diamond, it will glow red and white.  A reaction will then occur between the diamond surface and air, converting the carbon in the diamond to carbon dioxide and carbon monoxide. 

Both gases are colorless and odorless. Therefore, your diamond will vanish into thin air. The good news about most diamonds is that they contain impurities like nitrogen and may not completely disappear. Most colorful diamonds have impurities other than carbon.

Read: Does Wood Conduct Electricity?

Diamonds burn at extremely high temperatures and won’t burn in an ordinary fire. The diamond will only burn if the heat source is hotter than 1652°F (900°C). Adding liquid oxygen is the quickest way to ignite diamonds.

When you try to burn carbon, you’ll receive one of two outcomes:

  • In the presence of oxygen: Simply put, a diamond will burn. The diamond’s surface will appear white and cloudy on the outside. If the heat source is turned off, you can scrape off the burnt diamond surface to expose a considerably smaller, crystal-clear diamond.
  • In a vacuum(no oxygen): The diamond will initially change into graphite, most likely amorphous graphite, before becoming vapor or gas at higher temperatures. Such a condition happens because high temperatures will break down the diamond. 
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Since graphite is more stable and favorable in typical, low-pressure conditions, the diamond transforms its structure to graphite because there is no oxygen to react with.

Burning diamonds in a regular fire is challenging; thus, it is primarily done in industrial applications. However, each diamond is unique, and the quality of the diamond, as well as other external factors, will affect how it burns.

Does Diamond Melt in Fire?

If oxygen is present, a diamond will melt at a temperature of 1252(700°C). Diamonds will melt at a minimum temperature of roughly 8132°F (4500°C) without oxygen. Every material has a melting point, and a diamond is no different. However, molten diamonds are uncommon; most people probably haven’t heard of them.

Because diamonds cannot melt under normal atmospheric pressure, a laboratory might be necessary. Diamonds can be challenging to melt because they will first transform into graphite before melting into liquid without oxygen. Before melting, you must create high-pressure conditions to stop the diamond from converting to graphite.

The process of melting diamonds is as highlighted below:

  1. When you introduce oxygen, the diamond burns at a modest red heat.
  2. As the temperature rises, the diamond transforms into a white heat.
  3. The diamond continues to burn with a light blue flame even after you remove the oxygen heat source.
  4. The diamond crystals get smaller until they ultimately disappear.
  5. The flame will eventually go out after flickering briefly. If the diamond were pure, there would be no trace of it.

It is important to remember that diamond is a very brittle material and that melting it is likely to damage it. Carbon compounds such as diamonds often become a gas at high temperatures without first becoming a liquid.

Conclusion

The ability of diamonds to conduct heat but not electricity seems to be one of its unique features. It relies on lattice vibrations because it lacks free electrons, whose vibration could have allowed it to transport heat. Doping appears to help alter the structure of diamonds so they can conduct electricity.