Copper mine in Bor, Serbia.
Copper mine in Bor, Serbia.

Scientists have warned that many of the metals used to make gadgets such as smartphones have no adequate substitute, and that shortages caused by war or disaster could set technology back decades.

The paper, written by researchers at Yale University, identified 62 metals or metalloids used to make a range of products.

They found that of the metals tested none had a substitute that worked equally well, and for 12 no substitute at all could be found.

The 12 included rhenium, used in turbo engines and radiation screens, lanthanum, used in hybrid car batteries, and europium, used for lasers.

"The best substitute for a metal in a particular use is not always readily apparent," wrote professor Thomas Graedel, who led the study.

"It is paradoxical that the materials complexity of modern products brings with it a heightened level of risk," he wrote.

The study identified the US, South Africa, Australia, Congo and Canada as the countries with the largest metal reserves. "A national disaster or extended political turmoil in any of them would significantly ripple throughout the material world in which we live," said Graedel.

The study warns that growing populations and expanding demand for hi-tech devices risked "straining the resource capacities on which we draw," and that the dependence countries have on one another for these metals increases the risk of "geopolitical machinations" over their supply.

This was highlighted in 2010, when China announced restrictions on the export of a number of rare metals but allowed Chinese companies to continue using them freely.

The move caused the prices of the metals and the gadgets that contain them to rise.

In 2011, Malcolm Preston, PricewaterhouseCoopers' global sustainability leader, said that the increasing scarcity of commodities key to technology production was a "ticking time bomb".

"Many businesses now recognise that we are living beyond the planet's means," he told the Telegraph.