Chemistry Behind Diamonds
Chemistry Connections
Episode #11
Welcome to Chemistry Connections, my name is Lilly Wurtz and my name is Annie Stocks Natalias and we are your hosts for episode #11 called The Chemistry Behind Diamonds. Today we will be discussing the structure of diamonds as well as the main method used to create artificial diamonds: the high pressure, high temperature method.
Segment 1: Introduction to DIAMOND STRUCTURE
- Diamonds are made of elemental carbon and are allotropes of carbon. Allotropes are the same element but with different structures and arrangements in space.
- Diamonds form covalent network solids. Each carbon atom is covalently bonded to 4 other carbon atoms with covalent bonds. Covalent bonds involve the sharing of electrons so that the valence shell is satisfied. A repeating pattern forms a 3D network of atoms.
- “Real” diamonds (made naturally) were formed billions of years ago deep in the earth’s mantle and were brought to the surface most likely by a volcanic eruption. They take very long to form, making them essentially nonrenewable.
- Synthetic (or lab grown) diamonds can grow in just one week in a lab. These diamonds are not often used for jewelry but rather used industrially.
Segment 2: The Chemistry Behind CREATING SYNTHETIC DIAMONDS
- There are many methods used to create diamonds. This includes high pressure, high temperature, chemical vapor deposition, detonation of explosives, and ultrasound cavitation.
- These methods use something called diamondoids, which are very small pieces of diamond.
- In the High Pressure, High Temperature method, the large amount of pressure needed is supplied by the “press”.
- In the high pressure, high temperature method, diamond seeds are placed at the bottom of a press. The press is heated above 1400 °C which melts a solvent metal. The metal then causes the high purity carbon source to dissolve. This solution is transferred to the small diamond seeds and the precipitate grows the diamondoid into a large, synthetic diamond.
- The reason you are able to dissolve the carbon into the metal is because of the strength of the various intermolecular forces. Adding heat and pressure, adds so much energy that the intermolecular forces are overcome. This causes the particles to separate because the forces holding them together are weakened. These weakened forces in both the carbon and the metal allow the solution to form.
- The solute-solvent attractions are stronger than both the solute-solute attractions and the solvent-solvent attractions. This creates an alloy, which is normally a metal dissolved into another metal but it can also be created with carbon dissolved into a metal. This solution becomes supersaturated, meaning that the metal can’t hold any more carbon. The carbon then precipitates in the form of a crystal, growing the diamondoid.
Segment 3: Personal Connections
- You can condense a sometimes multi billion year process into less than a week.
- Many of the diamonds found in the past and those used today can be dated back to the formation of the earth and being able to recreate something formed by such a profound event as the creation of the planet in a simple lab is amazing.
- Even though they have not been widely adopted by jewelers, they look identical to the naked eye. This is because they are chemically identical and are diamonds. This is why using the words “real” and “fake” aren’t accurate. They are both real, one is just lab grown. Because synthetic diamonds are, in fact, “real” diamonds, they will last forever, which is the main allure of diamonds in the first place.
- Diamonds aren’t a complicated compound but rather the form of a single element. Imagine the fact that graphite and diamonds are the same thing just in different forms.
- They are incredibly important in industrial settings as well as because of their use in engagement rings and jewelry.
Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.
Sources:
https://en.wikipedia.org/wiki/Synthetic_diamond
https://www.azom.com/article.aspx?ArticleID=8494
https://www.impressjewelers.com/blog/how-are-diamonds-made-and-what-are-diamonds-made
https://www.diamonds.pro/education/how-diamonds-are-formed/
Music Credits
Warm Nights by @LakeyInspired
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