The Chinese government is limiting domestic production of rare earth elements (REEs) in the second half of the year, a move likely to crimp international exports and send prices for the critical materials soaring, according to a report from Reuters, based on information from Adamas Intelligence.

Low-atomic weight REEs, lanthanum and cerium, are used in petroleum-refining catalysts, automotive catalytic converters, and phosphors and as additives in glass for applications such as flat-panel displays, cell-phone screens, and camera lenses. Neodymium, another light REE, is alloyed with iron and boron to make the strongest-known permanent magnets. Other light REEs are used in steelmaking and alloying.

The heavy REE dysprosium is typically added to permanent-magnet alloys at a level of 1–3% to improve magnet operation at elevated temperatures. Terbium is used in green phosphors, which are found in electronics.

For the second half of 2018, China’s quota for rare earth separation and smelting has been cut 36%, an attempt to better control the market, according to Adamas, a research firm that closely tracks the rare earths industry.

China’s decision to limit domestic rare earth production to 45,000 tonnes for the second half of 2018—the lowest in more than five years—provides only enough supply for China’s domestic buyers, according to Adamas.

China is the largest producer and consumer of rare earths; Chinese exports typically supply around 80% of the globe’s rare earth needs, about 156,000 tonnes annually. The move is already forcing manufacturers to search for alternative supplies.

While China is likely to attend to its own needs before exporting, increased exports would require the country to draw on already-low inventories of neodymium (Nd), prasesodymium (Pr) and dysprosium (Dy), used in electric vehicle motors, said Ryan Castilloux of Adamas.

Prices for one key rare earth mineral, PrNd Oxide, could increase by 10% to 50% within the next 12 months, and is on track to double in price within next five years as demand outpaces supply, Castilloux said.