Artist’s illustration of gold compressed to ultra-high pressures by laser pulses at the National Ignition Facility.Jacob Long/LLNL
Scientists have achieved the most detailed look ever at how gold behaves when pushed to pressures almost beyond imagination. In a new study highlighted by Phys.org, researchers compressed gold to about ten million times Earth’s atmospheric pressure and recorded the highest-pressure structural measurement ever made for the metal. The results help resolve long-standing disagreements about how gold behaves when squeezed to the limits and strengthen its role as a reference material in high-pressure science.
These conditions are similar to the crushing environments deep inside giant planets, and recreating them on Earth demands extraordinary tools. The experiments were led by Lawrence Livermore National Laboratory in collaboration with other institutions. To reach the needed pressures, the team relied on carefully tailored laser pulses generated at the National Ignition Facility and the OMEGA EP Laser System. The lasers compressed gold samples so rapidly that the metal stayed cool enough to remain solid, allowing scientists to capture clear atomic-scale snapshots.
Using ultrafast X-ray diffraction, the researchers measured how the atoms rearranged within a billionth of a second. According to LLNL scientist Amy Coleman, this is the first definitive look at gold’s crystal structure under such extreme compression. She explained that facilities only recently gained the capability to both create these pressures and take accurate structural snapshots, which finally allowed scientists to settle debates between theoretical predictions and earlier experiments.
Gold normally forms what is known as a face-centered cubic structure. This pattern has long been considered stable even under intense pressure, yet models disagreed on when it might begin to break down. The new measurements show that the structure remains intact to far higher pressures than some predictions suggested, surviving well beyond conditions found at Earth’s core. At even greater compression, the researchers observed the first signs of a transition toward a body-centered cubic structure. Instead of one pattern replacing the other outright, the two structures briefly coexist, revealing the exact way the shift begins.
Understanding this transition has practical implications. Gold is widely used as a pressure calibrant, and errors in its behavior at extreme pressures can ripple outward into other scientific measurements. Coleman noted that knowing its structural limits with precision helps ensure accuracy in experiments ranging from planetary interior studies to the design of new materials.
The full study is available in Physical Review Letters.
