Terbium

"Myanmar is the world's third-largest source of rare earths after China and the US, and last year it accounted for almost half of the global mining of two especially important elements: dysprosium and terbium, which are essential for electric vehicles, wind turbines and certain military gear. […] The most important application of dysprosium and terbium, which belong to a subgroup known as the heavy rare earths, is in devices called neodymium boron magnets, or neo magnets for short. In small quantities, dysprosium and terbium allow neo magnets to operate at far higher temperatures than they otherwise could. Thus improved, they're key components in the drivetrains of EVs; the stronger the magnets, the more efficient an electric motor can be. They can also enhance the rotation of wind turbines and are used in the precision targeting systems of missiles."