Super Hard Cubic Aluminum

Aluminum oxide (Al2-O3) in it’s crystalline form is known as corundum and is second to diamond on the hardness scale. When it includes traces of chromium, creating a red color, it is called ruby and with traces of chromium, titanium, iron or other elements creating other colors, it is called sapphire.

Creating the Heart of a Planet in the Heart of a Gem – [slac.stanford.edu]

Although materials scientists have theorized for years that a form of super-dense aluminum exists under the extreme pressures found inside a planet’s core, no one had ever actually seen it.

Until now.

A team including researcher Arturas Vailionis of SLAC and Stanford blasted tiny bits of sapphire with a new table-top laser device that penetrates crystals and sets off micro-explosions inside them, creating powerful shock waves that compress the surrounding material. Under these extreme conditions – terapascals of pressure and temperatures of 100,000 Kelvin – warm dense matter forms, the state of matter between a solid and a plasma.

Because sapphire is a form of aluminum oxide, or alumina, researchers expected to find evidence of various phases of high-pressure alumina inside the gem. Instead, they observed minuscule amounts of a surprisingly stable, highly-compressed form of elemental aluminum called body-centered cubic aluminum.

Micro-explosion reveals new super-dense aluminium – [anu.edu.au]

An international team of researchers including scientists from The Australian National University have created a new, super-dense version of aluminium that could lead to efficient production of new super-hard nanomaterials at a relatively low cost.In a paper published today in Nature Communications, the group has described how they discovered a way to produce body-centred-cubic aluminium, which is 40 per cent more dense. Super-hard aluminium was predicted to exist more than 30 years ago but has never before been observed.Professor Andrei Rode from the Laser Physics Centre at ANU said the state of any material depends on temperature and pressure. “For example, water turns into ice at low temperatures and hydrogen gas actually becomes metallic under extreme pressure in the middle of a star,” he said.“Lab experiments on producing high pressure and temperature generally use a diamond anvil with a point on one end to produce high pressure but this is limited by the strength of the diamond, which in the case of aluminium, is not hard enough to crush into a new state.

Evidence of superdense aluminium synthesized by ultrafast microexplosion – [nature.com]

Abstract
At extreme pressures and temperatures, such as those inside planets and stars, common materials form new dense phases with compacted atomic arrangements and unusual physical properties. The synthesis and study of new phases of matter at pressures above 100 GPa and temperatures above 104 K—warm dense matter—may reveal the functional details of planet and star interiors, and may lead to materials with extraordinary properties. Many phases have been predicted theoretically that may be realized once appropriate formation conditions are found. Here we report the synthesis of a superdense stable phase of body-centred-cubic aluminium, predicted by first-principles theories to exist at pressures above 380 GPa. The superdense Al phase was synthesized in the non-equilibrium conditions of an ultrafast laser-induced microexplosion confined inside sapphire (α-Al2O3). Confined microexplosions offer a strategy to create and recover high-density polymorphs, and a simple method for tabletop study of warm dense matter.

SEE ALSO:
Diamond Mechanosynthesis
Photonic Colloidal Crystals
Quasicrystals
5-fold Crystal Symmetry

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