Scientists have used a new technique to synthesize diamonds at normal, atmospheric pressure and without a starter gem, which could make the precious gemstones much easier to grow in the lab.
Natural diamonds form in Earth’s mantle, the molten zone buried hundreds of miles beneath the planet’s surface. The process takes place under tremendous pressures of several gigapascals and scorching temperatures exceeding 2,700 degrees Fahrenheit (1,500 degrees Celsius).
However, the high pressures and temperatures are difficult to produce and maintain. Plus, the components involved affect the diamonds’ size, with the largest being about a cubic centimeter, or about as big as a blueberry. Besides, HPHT takes a fairly long time — a week or two — to produce even these tiny gems. Another method, called chemical vapor deposition, eliminates some requirements of HPHT, like high pressures. But others persist, like the need for seeds.
The new technique eliminates some drawbacks of both synthesis processes. A team led by Rodney Ruoff, a physical chemist at the Institute for Basic Science in South Korea, published their findings April 24 in the journal Nature.
The researchers housed the crucible in a home-built chamber maintained at sea-level atmospheric pressure, through which superhot, carbon-rich methane gas could be flushed. Designed by co-author Won Kyung Seong, also of the Institute for Basic Science, this 2.4-gallon (9 liters) chamber could be readied for experimentation in just 15 minutes, allowing the team to rapidly undertake runs with different concentrations of metals and gases.
