Diamonds are one of the rarest materials known to mankind with marvelous physical as well as chemical characteristics. They showcase extreme hardness, durability, and possess extreme electrical and thermal properties. Before discussing the thermal properties of a diamond. Let us first know what is meant by thermal conductivity.
The thermal conductivity of any material can be describe as its ability to transfer heat from a region of high temperature to low temperature. Solids that have crystalline structures have high thermal conductivity than other solids which are amorphous in the state. This is the same reason why metals showcase greater thermal conductivity than nonmetals, liquids, and gases in particular.
The molecules in amorphous solids are irregularly order. Therefore they have lesser thermal conductivity than those regularly arranged molecule metals.
Moreover, due to the vibratory motion of the crystal lattice. There is an additional transfer of heat in solids towards the decreasing temperature. This is also why gases have far less thermal conductivity than liquids and metals. The molecules in gases are placed far apart from each other.
Diamonds have a highly crystallized structure as compared to other metals. The perfectly arranged atoms in them make it possible for them to conduct heat more rapidly and easily than other metals.
Thermal Conductivity of Diamond
Diamonds have strong covalent bonding and low phonon scattering. The diamonds originated from nature has a thermal conductivity of about 2200W/(m-K). Which is five times more than the most thermally conductive metal known, i.e. silver. The thermal conductivity of monocrystalline synthetic diamonds. Which are enriched to 99.9 percent of the 12C is even higher, measuring up to 3320 W/(m-K).
In the case of synthetically or artificially formed diamonds. The thermal conductivity that they showcase is even higher than the naturally form ones due to their level of purity.
Such diamonds, which are produce by the CVD or the Chemical Vapor Deposition process has opened door to various possibilities and needs they can suffice industrially. One such need of CVD formed diamonds is to spread out heat to a single larger piece of diamond or larger pieces of diamond. For this to be done, the diamonds need to serve as platforms for high power diodes and solid-state lasers. Because of the diamonds being of the state of the art quality as they are. The thermal resistances are reduce to the lowest form possible.
Another possible use of these CVD formed diamonds is to spread the heat entirely by fabricating the device within the entire diamond. In this case, the fabrication gets hamper due to the lack of suitable electronic donors.
Usage of the Diamond’s Thermal Conductivity
- Because of such high conductance diamonds are already being used in the semiconductor manufacturing industries to prevent any form of overheating. It should also be noted that, when the temperature is lower, the conductivity even becomes better, reaching up to the mark of 41000 W/(m-K) recorded at a temperature of 104 K.
- Jewelers and gemologists use this criterion of thermal conductivity of diamond’s to distinguish them from the fake ones or lookalikes. They use electronic thermal probes which consist of a pair of battery-powered thermistors. These thermistors are mount in a fine copper tip. One of the thermistors heats the diamond or works as the heating device while the other measures the temperature of the copper tip. If the stone or gem being test as a real diamond, then the temperature will drop considerably on the copper tip. The whole testing procedure takes about two to three seconds and delivers firm results. The older devices and probes, however, were fooled when moissanite was tested with them. As moissanite showcase similar thermal conductivities as diamonds and are themselves a crystalline form of silicon carbide.
What Causes Diamond Feel Warm To The Touch?
To answer the above question more appropriately, we have to understand some simple chemical terms.
The first one to be talk over is known as “Specific Heat”. The specific heat of any substance is the amount of heat or thermal energy require to raise the temperature of the particular substance per unit of mass. It is also one of the physical properties that any substance possesses.
The next one to be discussed is known as “Thermal Conductivity”. The thermal conductivity of any material or substance can be simply define as the substance’s ability to conduct heat. According to the second law of thermodynamics; we know that heat is something that flows from a hot environment or body to a cold environment. Ultimately balancing out the temperature difference between to former and the latter cases. It is also one of the physical properties that anybody or material possesses.
Thermal or Heat conductors
Diamonds are one of the best thermal or heat conductors known to mankind. Heat is nothing but the vibration of energized molecules inside a substance. Diamonds have a very rigid tetrahedral crystalline structure meaning groups of carbon atoms form up small triangles with their neighboring atoms forming a three-dimensional structure. Triangles are believe to be the most rigid shapes present. And this is exactly why they are used to form mechanical constructions such as bridges. Now, when an atom of a diamond gets “heat up” or energized. It quickly and instantaneously transfers its energy to the neighboring atom and the next to the latter. This whole procedure happens very fast as a whole, and the diamond gets heat up instantly.
Whenever they come in contact with any heated surface than them they follow the second law of thermodynamics. And rapidly take away the heat from the surface in contact or surrounding, making themselves warm.
The Diamond Feel Warm to The Touch
So, whenever we go and touch a diamond, they take away some amount of heat from our finger’s portion that is in contact with it and raises its temperature. On the other hand, the part of our finger that comes in contact with the diamond loses its temperature. Resultantly, the diamond feel warm to the touch.
To speak truly, there are so many interesting minuscule happenings. That go on happening everywhere in our nature without even thinking about it. Just like our human body, every material or substance in this world, be it metal or nonmetal, have specific properties of their own.
Diamonds are one of the rarest wonders that we have come to know as humankind. As they showcase such beauty and preciousness; it is bound to be that these stones also have some special kinds of physical and chemical properties of their own. The aforementioned feel is one of such display of its beautiful physical properties; nothing more.