Diamonds have a lot of interesting properties.
They hold the number one spot on the Mohs scale, for instance, which makes them the hardest material in the world. They form under extreme heat and pressure and can handle temperatures of up to 700 degrees Celsius before being affected at all.
Crazy, isn’t it?
And while we’re on the subject of heat, there is one more property we want to mention – thermal conductivity. Diamonds are extremely efficient thermal conductors, which sort of makes sense when you think about it.
After all, it takes so much heat to make them, and they can withstand even more.
But why can diamond conduct heat?
Well, we’re here to answer that question. There are a few things we’ll have to cover first – like what thermal conductivity is in the first place. But don’t worry; we won’t go too far down the physics rabbit hole.
Anyways, enough of the chitter-chatter, let’s get this show on the road.
Why Can Diamonds Conduct Heat?
Alright, so this question is one that deserves a longer explanation. But we feel the obligation to give the simple answer right away – just to put the whole thing into perspective before going any further.
To put it simply, heat is all about vibrations – and diamonds can vibrate a lot. We know it sounds weird – but let us explain.
See, all heat does is make the atoms of any substance vibrate. The more the atoms vibrate, the hotter they will get. Once the atoms vibrate more than the bonds between them can handle, the substance will start changing its physical state from a solid to a liquid.
The same goes when you turn things around: If atoms aren’t vibrating, it gets colder.
That is actually how most thermal measuring scales are set up: On the Celsius scale, 0 represents the temperature at which water freezes while it starts to boil at 100 degrees.
On the other hand, the Kelvin scale gives us some different temperatures to work with: When converted to Celsius, 0 Kelvins translates to -273.15 degrees.
Now, that number might sound random – but it’s far from it. That is a temperature called absolute zero.
What does that have to do with thermal conductivity? Well, a lot actually.
See, at -273.15 degrees, there are absolutely no vibrations between the atoms, which means that there is – well, nothing. It’s a temperature that can’t exist in reality since there has to be some movement of the atoms for anything to exist.
Okay, so how do we translate that to diamonds and thermal conductivity? Well, it’s simple, really. Remember how we said that diamonds form under extreme heat and pressure?
Due to those conditions, the carbon atoms are packed together tightly and in crystal matrixes, meaning that the covalent bonds between those atoms are very strong. And because of this, if one atom starts to vibrate, all the other ones that are bonded with it vibrate as well.
The vibration gets spread out quickly and efficiently throughout the crystal structure, and with it, the thermal energy gets evenly distributed, too. That, in essence, is what makes diamonds such great conductors.
We know – but that’s as simple as we can go, we promise!
What Is Thermal Conductivity?
Alright, so, with all that vibration talk in mind – what exactly is thermal conductivity?
Well, it’s the ability of something to conduct heat. Or, to translate that into regular terms, it’s the measurement of how quickly or slowly materials will take heat from another object – and how quickly or slowly they will cool down after that.
Good thermal conductors will take the heat and pass it through the atom bonds quickly, while thermal insulators don’t transfer the vibrations that we talked about earlier very well.
Most metals, for instance, are pretty good thermal conductors, while materials like styrofoam would be good thermal insulators. That’s why it’s often used for isolating walls of houses.
Let’s say that you managed to warm up your house during a cold winter night.
If you have a thermal insulator spread out on your walls, it won’t conduct that heat through itself very well, which means that your house will stay warm. But if you have a thermal conductor on your walls, it will conduct the heat through itself and pass it on to whatever’s on the other side.
Due to the second law of thermodynamics, heat will always flow from a hot environment to a cold one until the two are eventually evened out.
If you put a solid object between those two environments, you will either speed up or slow down the process. If you’re looking to keep your house warm – like in the example from a moment ago – that solid object should be an insulator.
But if you want to speed up the process, you’d go with a conductor.
Diamonds are great at conducting heat – although they’ll probably eat away at your budget if you decide to use them in an industrial project. That is why metals like copper will always be the more popular option.
There’s also the issue of shape and size.
Diamonds are great conductors, but they’re hardly practical. If you’re looking for something you can shape and mold into whatever you want, metal will always be a better option.
Diamonds can’t melt easily, and even if you manage to make them do so, they’ll start vaporizing before they actually melt. It’s a very interesting process, we admit – but not what you would want in your conductor.
But the fact is that they conduct heat extremely well, so they are still used in many fields and industries – even if their application is limited.
Can Diamonds Conduct Electricity?
So, that’s pretty much how thermal conduction works.
We could go deeper into the thermodynamics of the whole deal, but we’d like to cover one more subject – electrical conductivity – quickly.
Can diamonds conduct electricity? And are the two things connected in a way?
Well, while diamonds are great thermal conductors, they’re terrible at electrical conduction. That is to say; they’re pretty darn great electrical isolators.
We know, again with this!
See, the two fields do have some similarities – but there’s one crucial difference: The atoms of a certain material need to vibrate in order to conduct thermal energy. But electrical energy works a bit differently.
While those atoms vibrate, the electrons – and other particles around them – can hold or conduct an electrical charge. Not only that, the two can affect each other at times.
When electrical energy is being conducted in between the atoms, they tend to get shaken up. There can’t be more electrical energy than the atoms can handle without consequences. That is why, for instance, a cable can start to melt if there’s too much electricity going through it.
Cables are actually pretty good examples of both fields working together:
There are electrical conductors that are made to go from their own electrical source to whatever machine needs the power at the moment. There’s copper wire, which is a thermal and electrical conductor, on the inside of the cable – and the whole thing is surrounded by rubber, which is a great thermal and electrical insulator.
The copper can conduct electricity efficiently, meaning that it has free particles running through it in between its atoms at incredibly high speeds.
But because this makes the atoms vibrate a whole lot, the rubber is used to keep the heat from spreading around – which helps those free particles sprint through the cable more efficiently.
Diamonds can conduct heat well, as we already said, but they are electrical insulators, meaning that no free particles can manage to go through its dense carbon matrix.
In fact, the only type of diamond that can work as an electrical semiconductor is the natural blue diamond. These have traces of boron in them, meaning that there’s room between them and the carbon.
Because of this, there are free particles roaming around with the addition of charged holes in between. And in case you were wondering, blue diamonds are still pretty great thermal conductors, though they’re not as good at it as regular diamonds are.
Can Diamonds Melt?
How about we get back to the thermal part of the story? That is, after all, why we’re here today.
Now that we know that diamonds are good thermal conductors, how about we talk about what happens to them when they get exposed to high amounts of heat? They’re formed under some pretty extreme conditions, so this might leave you wondering: How much heat can they take?
Well, a lot, as it turns out.
Not that it comes as a big surprise, but diamonds are pretty darn resilient to heat. You might’ve noticed that we mentioned them starting to get affected only at about 700 degrees Celsius.
But it’s essential to note that that’s the point at which they start to show any change whatsoever. It’s only when the temperatures start going over that number that they get truly affected by the extreme heat.
What’s pretty interesting is that they are actually prone to shattering when they receive a blow from an object like a hammer – but they will show no signs of weakness when they get tossed in magma.
Most materials would melt, explode, or evaporate. Diamonds, however, just kind of float in the rivers of lava and magma. Not only that – they can sometimes get brought up to the surface in magma.
It’s vital to say magma and not lava; these two aren’t the same, contrary to popular belief. Lava is the liquid form of magma, and magma is the solid form of lava. Diamonds can float in lava but as a part of a rock that hasn’t yet melted.
By the way, that’s pretty much all that lava and magma are – just rocks that have been exposed to so much heat that they started to liquify. Mind-blowing, right?
But unlike your usual minerals and rocks, diamonds stay diamonds – when cooled off, that is – and that’s how they end up using eruptions as a transportation system to the surface.
We’re not often looking for diamonds in magma or lava; let’s get that straight. But it’s interesting to think that they come up in such an extreme manner.
So not only can diamonds conduct heat incredibly quickly and efficiently – they don’t get affected by it, no matter how high the temperatures rise!
How Are Diamonds Formed?
We mentioned multiple times that diamonds are formed under extreme heat and pressure – but how does it actually work? And how does it affect their thermal conductivity?
Well, let’s find out.
There is a lot of carbon underneath the Earth’s surface, and it’s pretty darn common all around us, as well. Because of the extreme conditions found inside the Earth – mainly the heat and the pressure – the carbon atoms are pushed together until they form a strong bond.
The more carbon happens to be in one pocket of the Earth’s crust, the bigger a diamond will be.
They often take a long time to form; sometimes, it takes them thousands of years. And the more time they spend forming, the bigger they become.
There are often impurities and imperfections on the inside (and on the surface) of the diamonds, which makes sense since the conditions that they grow in are hardly perfect.
Because of this, not all diamonds can be perfectly translucent and colorless. The imperfections don’t allow the light to travel through the material.
But the one thing that all those imperfections don’t affect is its thermal conductivity.
The atoms are still arranged in the same manner, no matter how pure or imperfect a diamond is. The appearance of the diamond only comes into consideration if it gets prepared for sale in the jewelry industry.
But when it comes to industrial purposes, the only thing that matters is the hardness and the thermal conductivity. Luckily, diamonds are pretty famous in both of these fields.
We mentioned that they’re good at conducting heat – but we have yet to mention how good. And let us tell you, diamonds are champions of sorts in this category: Diamonds have the highest thermal conductivity of any natural material at 22 W/(cm·K).
That means that those tightly packed carbon atoms are so perfectly arranged that there’s no other material in our world that can transfer heat better than them.
You probably don’t want to use diamonds to insulate your house – but they’re a lifesaver if you’re trying to transfer some heat from one place to another quickly.
Learn More: Diamond History: How They Form And How They’re Found
So, there you have it! We did as much research as we could and dug up all the available info about the thermal conductivity properties of our favorite gem.
And as you’ve probably noticed, there’s a lot to talk about here. Diamonds aren’t the perfect material, and they do have their flaws and weaknesses.
But their atomic structure is something that should be admired. It’s incredible that they managed to form all on their own in nature.
All that’s left for us to do is admire them – and we hope that we managed to inspire that sense of admiration with this article!