Superdiamonds? - Scientists discover superconductivity in diamond

Scientists working at the Russian Academy of Sciences and the Laboratory announced last week the discovery of superconductivity at ultracold temperatures in cubic diamond. The discovery offers the potential for a new generation of diamond-based device applications and even suggests that superconductivity in silicon or germanium, which also forms in the diamond structure, may be possible.

In findings published in the scientific journal Nature, the Russian - American team of scientists report their discovery of superconductivity in a boron-doped diamond-structured carbon material that had been synthesized at very high pressures and temperatures. The diamond material was fabricated in Russia by scientists working at the Institute for High Pressure Physics (IHPP) at the Russian Academy of Sciences and brought to Los Alamos where superconductivity in diamond was discovered.

According to Vladimir Sidorov of Condensed Matter and Thermal Physics (MST-10) and IHPP, "gem diamonds are desired for their sparkling brilliance and extreme hardness. This discovery of a totally unexpected new facet of diamond enhances its desirability, not to the well-attired, but to science and technology."

Optical and scanning electron microscopy images of the cubic diamond material. Top image shows cubic diamond material synthesized by subjecting graphite and boron carbide (B4C) to high pressure, high-temperature conditions. D is diamond and G is graphite. Bottom image shows scanning electron microscope view of the synthesized boron-doped diamond. Images courtesy of Vladimir Sidorov

Diamonds conduct heat more effectively than copper and can withstand very high electric fields. These properties are the result of the ways in which electrons arrange themselves in the atomic structure of diamond. This same electron arrangement makes it impossible for diamond to conduct electricity. However, by subjecting a graphite and boron carbide mixture to pressures of nearly 100,000 atmospheres and temperatures of roughly 4,000 to 4,600 degrees Fahrenheit, scientists were able to transform diamonds from a 'supergem' to a superconductor that carries electricity with no resistance at a temperature of minus 450 degrees Fahrenheit.

Boron atoms have one less electron than carbon atoms and because of their small atomic radius, boron atoms are relatively easily incorporated into the diamond atomic structure. Separately, both boron and diamond are not electrical charge conductors, but instead are quite good insulators. Once they are combined, the resulting diamond becomes doped with electrical charge carriers. Incorporating a small number of these charge carriers in diamond allows fabrication of transistors, but adding more carriers creates superconductivity.

While there is a great deal of research yet to do, the discovery of superconductivity in diamond-structured carbon suggests that new forms of diamond-based integrated circuits may be possible.

Silicon or germanium, which also form in the diamond structure, may also exhibit superconductivity under certain conditions. Although it is highly speculative at this point, this means that someday scientists might be able to create a form of superconducting silicon that would allow computers to operate even faster than imagined.

-- Todd Hanson

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