Diamond anvil cell

The diamond anvil cell emerged because high-pressure physics was imprisoned by opacity—existing pressure devices crushed samples in total darkness, allowing no optical observation of transformations. Diamond, uniquely among materials strong enough to reach extreme pressures, is also transparent.

In 1958, a team at the National Bureau of Standards in Washington—Charles E. Weir, Alvin Van Valkenburg, Ellis R. Lippincott, and E.N. Bunting—constructed a manual screw-driven device using gem-quality diamonds as opposing anvils. Two precisely cut diamond faces squeezed a sample between them, concentrating enormous force on a tiny area. Initial versions achieved pressures exceeding 30,000 atmospheres (about 3 gigapascals).

Van Valkenburg's key insight came while preparing a sample for infrared spectroscopy. Nervous about diamond alignment, he checked through a polarizing microscope. To his astonishment, he saw colored bands and fringes—he was the first person to directly observe pressure-induced changes in real time. The transparent anvils transformed high-pressure research from blind compression to visible science.

Van Valkenburg also pioneered the gasket technique: placing a washer-shaped foil of metal (rhenium or tungsten) between the diamond faces. Under extreme pressure, the metal flows and fills the central hole with fluid, creating hydrostatic conditions that distribute pressure evenly across the sample.

The seminal 1959 paper—'Infrared studies in the 1- to 15-micron region to 30,000 atmospheres'—launched a revolution. Simultaneously and independently, John Jamieson at the University of Chicago developed a similar device, confirming the concept's inevitability.

Subsequent decades pushed pressures higher: 100 GPa by the 1970s, megabar pressures (100 GPa) by the 1980s, and eventually pressures exceeding those at Earth's core (360 GPa). The DAC enabled discovery of new phases of matter, simulation of planetary interiors, and synthesis of novel materials.

In 1986, the Franklin Institute awarded Van Valkenburg the John Price Wetherill Medal, recognizing that the DAC 'has revolutionized high-pressure research, by allowing static pressures equivalent to that in the earth's core to be produced in the laboratory.' Van Valkenburg died in 1991, the last surviving co-inventor of an instrument now considered world-class for scientific research.