Rare-Earth Elements (REEs)
Context:
Countries worldwide are increasingly seeking control over Rare-Earth Elements (REEs) due to their critical role in green technologies, electronics, and defense systems.
What are they?
REEs are a set of 17 metallic elements in the periodic table
o They comprise the 15 lanthanides (from lanthanum to lutetium) plus scandium and yttrium
The lanthanides are typically shown as a separate row beneath the main table, while scandium and yttrium are located in the main table in Group 3
They are not necessarily scarce in the earth's crust but are called rare because they are dispersed in low concentrations and are difficult to separate from one another.
Magnetic Chemistry:
REE atoms have electrons in the 4f shell that are localised (stay close to the nucleus) unlike other electrons that form bonds
These localised 4f electrons maintain a strong magnetic moment, behaving like small, stable magnets
This unique structure allows REE magnets to have both high magnetisation(strength) and high stability (resistance to demagnetisation by heat or vibration).
Thus, REE magnets (e.g., Neodymium-Iron-Boron) are used in high-performance motors and generators
Optical Behaviour: The 4f electrons also allow REEs to emit light at sharp, specific frequencies when excited, making them ideal for producing stable colors in screens and lights.
Applications:
The most common application is Neodymium-iron-boron magnets (Permanent Magnets) which are essential for motors and generators (including in EVs and wind turbines)
They are used in electronics and optics for lasers, fiber optics and phosphors for screens
They are utilized in catalysts and ceramics like polishing powders, glass manufacturing, and chemical catalysts.
Why are they called Rare and issues with extraction?
Separation is difficult because neighbouring REE ions behave similarly in solution.
The industry uses solvent extraction which is a repetitive process to separate elements by their slight differences in solubility
Ores often contain radioactive thorium or uranium, and processing requires strong acids that generate hazardous waste.