Terbium
A heavy rare-earth metal used in small additions to raise high-temperature coercivity of NdFeB magnets for under-hood and high-duty EV motors. Extremely supply-constrained relative to light rare earths.
Overview
Terbium (symbol Tb, atomic number 65) is a silvery heavy rare-earth metal with a density of about 8.23 g/cm³ and a melting point near 1356°C. In automotive electrification it is valued as a grain-boundary and magnetocrystalline anisotropy enhancer: even 1–3 wt% terbium (often alongside dysprosium) in NdFeB magnets markedly improves coercivity at elevated temperature, reducing demagnetisation risk in compact, high-power-density traction motors and actuators. Terbium also underpins green phosphors (Tb3+), magneto-optic materials and some solid-state devices. Heavy rare-earth feed is scarcer than light REEs; historically much of the marketable terbium originated from ionic-adsorption clay deposits in southern China and Myanmar, with limited diversified supply. OEMs treating magnet thermal derating as a design constraint therefore treat terbium as a strategic, high-cost micro-addition and actively pursue grain-boundary diffusion, Dy/Tb thrifting and Tb-free high-coercivity magnet grades where feasible.
Automotive Applications
Similar Materials
Lanthanum
Rare Earth Element
The lightest rare-earth metal, used in nickel–metal hydride battery electrodes, FCC and automotive catalysts, optical glasses and polishing compounds. Abundant among REEs but still tied to concentrated separation capacity.
Praseodymium
Rare Earth Element
A light rare-earth metal co-produced with neodymium and used primarily in NdPr (didymium) feedstock for NdFeB permanent magnets that power EV traction motors and automotive actuators.
Samarium
Rare Earth Element
A rare-earth metal used as feedstock for samarium–cobalt (SmCo) permanent magnets that retain performance at high temperature and in corrosive environments. Distinct from finished SmCo magnet products already catalogued separately.
Scandium
Rare Earth Element
A light rare-earth / transition metal used in Al-Sc alloys for high-strength lightweight structures and increasingly in additive manufacturing. Supply is limited and concentrated in China, Russia and emerging Australian projects.
Properties
Category
Type
Rare Earth Element
Available Colors
Available Forms
Key Properties
- Heavy rare earth that strongly raises NdFeB coercivity
- Effective at low weight-percent additions and via GBD
- Enables higher motor operating temperatures
- Far scarcer than light rare earths (Nd/Pr)
- Supply historically concentrated in China/Myanmar ionic clays
- High unit cost; priority thrifting target for OEMs
Technical Specifications
Density
8.23 g/cm³
Tensile Strength
Not used as a structural metal; consumed as magnet micro-addition
Temperature Resistance
Melts at ~1356°C; enables NdFeB magnet grades rated for higher continuous motor temperatures (often 150–200°C class depending on design)
Sustainability
Sustainability Rating
Terbium recovery from end-of-life NdFeB magnets is technically established but collection and dismantling rates from vehicles remain low. Primary ionic-clay mining carries significant environmental and social risk. Magnet design thrifting, grain-boundary diffusion and recycling are the primary levers to reduce primary Tb demand intensity per vehicle.