Diamond info

Diamond has a unique combination of outstanding material properties. It is extremely hard, yet light, wear-resistant, chemically inert, electrically non-conductive and has a particularly low coefficient of friction. This makes diamond ideal for the most demanding mechanical applications.


General properties

Diamond fascinates with its unique combination of outstanding material properties and thus occupies a special position among all materials. Diamond is the material with the highest thermal conductivity at room temperature (4-5 times higher than the thermal conductivity of copper) and at the same time has excellent electrical insulation properties. At the same time, diamond has the greatest hardness of all available materials.

In addition to an extremely low coefficient of friction, diamond has a low coefficient of thermal expansion. Diamond is resistant to all known acids and bases. In addition, diamond is transparent from the ultraviolet to the far infrared spectral range. With a band gap of 5.45eV, diamond belongs to the group of semiconductors and can be doped both p-type and n-type.

Despite its extreme material properties, diamond only played a subordinate role as a material for a long time. The main reasons for this were the low natural occurrence and the high cost of producing diamond artificially at high pressures and temperatures. Another disadvantage of diamond was the small size of the single crystals, which largely limited its technical application to drilling and cutting tools and its use as an abrasive.

It was not until the early 1980s that the possibility of diamond synthesis at low pressures (a few mbar) and at relatively low temperatures (700°C-900°C) was discovered, triggering lively scientific and industrial interest. For the first time, it was now possible to deposit diamond from a gas mixture of hydrogen and methane, for example, over a large area as a polycrystalline layer on external substrates.

GFD is one of the first companies in the world to master the industrial manufacture of high-quality diamond coatings on a production-relevant scale.

Grid constant0.356 nm
Thermal expansion coefficient1.1 (10-6/K)
Density3.515 (g/cm3)
Charge carrier mobility Hole1600 cm2/(V s)
Charge carrier mobility Electron2200 cm2/(V s)
Break-through field strength107 V/cm
rel. Dielectric constant5,7
Band gap5.45 eV
Spec. Resistance10-3 – 1016 Ωcm
Thermal conductivity20 W/(cm K)
Refractive index2,42
Transparencyfrom IR to UV (225 nm)
Hardness10000 (kg/mm2)
E-modulus1140 GPa
Speed of sound17500 m/s

Mechanical properties

Diamond is the hardest material in the world and has exceptional wear resistance. Coupled with a very low coefficient of friction, diamond is ideal for the production of cutting edges for machining and non-cutting material processing. Furthermore, diamond is the “material of choice” for the production of microtechnologically manufactured components. Applications include diamond micro gears.

Diamond is an extremely chemically resistant material. It is resistant (inert) to all known acids and bases, even at high temperatures. In pure oxygen, diamond begins to oxidize at around 400°C. With a lower oxygen supply, e.g. in air, oxidation only begins at approx. 500°C. When in contact with iron, ensure that the contact point is well cooled. The exceptionally high chemical resistance is an ideal prerequisite for the use of diamond in many areas of technology, medicine and chemistry.

Electrical properties

The specific electrical resistance of undoped diamond at room temperature is around 10 orders of magnitude higher than that of monocrystalline ultra-pure silicon due to the large band gap of 5.45 eV between the valence and conduction band. Doping with acceptor atoms (e.g. boron) for p-type diamond has been mastered for several years. The production of n-type diamond, on the other hand, is still a challenge. At low dopant concentrations, the charge carrier mobility in diamond is 2200 cm2/Vs for electrons and 1600 cm2/Vs for holes and is therefore around 1.5 and 2.7 times greater than in silicon.

Thermal properties

In addition to its electrical properties, it is the thermal properties that make diamond interesting for industrial applications in the semiconductor industry. At room temperature, the thermal conductivity of diamond is approx. 20-25 W/cmK and is therefore approximately 4-5 times greater than that of copper and 15 times greater than that of silicon. The maximum of 50-60 W/cmK is reached at a temperature of approximately 80 K.

The thermal expansion coefficient of diamond is almost linear with temperature and is approx. 1.1×10-6/K at room temperature and is therefore comparable to that of Si and Invar (65% Fe + 35% Ni). The high thermal conductivity and high electrical insulation capacity of diamond enable it to be used as a heat spreader in high-performance electronic components.

In combination with the high optical transparency of diamond, its high thermal conductivity enables it to be used as a window material for high-power lasers or other intensive radiation sources.

Optical properties

Another impressive property of diamond is its high transparency over an extremely wide optical range. The transparency ranges from the far infrared to the deep ultraviolet spectral range (220 nm) and is only slightly impaired in the 2-6 µm range. These properties are retained even at high temperatures. In combination with its high thermal conductivity and low coefficient of thermal expansion, diamond is an ideal window and lens material for high radiant power.

Other interesting fields of application arise when the broadband transparency and the very high mechanical and chemical stability of diamond are combined. Windows for extreme ambient conditions are possible.


Diamond is ideal for the most demanding applications due to its extremely high sharpness and wear resistance.