graphitetodiamond

Graphite to diamond refers to the transformation of carbon from graphite, where carbon atoms are arranged in layered sp2 bonds, to diamond, which features a three-dimensional sp3 lattice. This conversion occurs naturally under extreme pressures and temperatures deep in Earth's mantle and can be replicated industrially through high-pressure high-temperature methods or chemical vapor deposition.

In industrial contexts, two main routes are used: high-pressure high-temperature (HPHT) and chemical vapor deposition (CVD). HPHT mimics mantle conditions by applying large pressures, typically around 5 to 6 gigapascals, and temperatures near 1200 to 1600°C. A metal catalyst is often employed to facilitate the transformation, and a diamond seed may be used to nucleate growth. HPHT commonly yields polycrystalline industrial diamonds or, with precise control, single-crystal gems. Impurities and defects influence color and quality.

CVD approaches transform graphite-derived carbon in a gas phase at lower pressures, using methane or other hydrocarbons in hydrogen, activated by microwave or RF plasma. Carbon deposits on a substrate, forming diamond films or crystals through controlled growth. CVD enables selective layering, improved purity, and the production of coating-grade diamonds as well as specialized single-crystal components for electronics and optics.

Properties of diamond produced from graphite include exceptional hardness and high thermal conductivity, with performance dependent on crystal quality and impurities. Applications span cutting and grinding tools, wear-resistant coatings, optical components, heat spreaders, and emerging quantum sensing uses involving NV centers.

Historically, synthetic diamond production began in the 1950s with HPHT methods, expanding in later decades to include CVD, which broadened applications beyond industrial abrasives to high-tech fields.