Why rare earth elements important?

1. What are rare earth elements?

Rare earth elements (REE) are made up of 17 elements, including scandium, yttrium and the lanthanides. Among them, seven elements including lanthanum, cerium, praseodymium, neodymium, promethium, samarium and europium are light rare earth elements (LREE), while terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium and yttrium are heavy rare earth elements (HREE). Because rare earths have the same outermost electron configuration, they have very similar properties.

The most abundant rare earth elements are found in the Earth's crust in amounts equal to nickel, copper, zinc, molybdenum or lead. Cerium is the 25th most abundant element of the 78 common elements found in the Earth's crust. Even the two least abundant rare-earth elements (thulium and lutetium) are nearly 200 times more abundant than gold. In general, rare earth elements are more abundant than silver and similar to copper and lead. But they are rare in the sense that mineralogists call them "dispersions" because they are mostly scattered around the Earth in relatively low concentrations. Rare earths are commonly found in alkaline volcanic rocks, carbonate rocks, hydrothermal veins, sedimentary sandstones and mine waste. Only a few places have large quantities of rare earths -- and most of them are in China.

In 2018, the cost of neodymium oxide with atomic number 60 was $107,000 per ton. By 2025, the price is expected to climb to $150,000. Europium costs the most - around $712,000 per tonne. Part of the reason they are so expensive is that rare earth elements are chemically symbiotic and difficult to separate from each other to make pure materials.

2. What are the applications of rare earth elements?

Many applications of rare earth elements are highly specific and alternatives are poor or unknown:

* Color cathode ray tubes and liquid crystal displays used in computer monitors and televisions use europium as a red fluorescent.

* Terbium is a green phosphor used in flat-screen TVS and lasers.

* Lanthanum is critical to the refining industry, which uses it to make fluid cracking catalysts that are 7 percent more efficient at converting crude oil into refined gasoline.

* Rechargeable batteries.

* Automotive pollution control catalyst.

* Neodymium is the key to making high-strength permanent magnets for efficient electric motors.

Two other rare earth minerals - terbium and dysprosium - are added to neodymium to keep it magnetic at high temperatures.

* Fiber optic cables can transmit signals over long distances because they contain erbium-doped fibers with periodic interval lengths that can be used as laser amplifiers.

* Cerium oxide is used as a polish for glass. Almost all polished glass products, from ordinary mirrors and eyeglasses to precision lenses, are finished with CeO2.

Gadolinium is used in solid-state lasers, computer memory chips, high temperature refractories and low temperature refrigerants to improve the high temperature characteristics of iron, chromium and related alloys.

* Yttrium, lanthanum, cerium, europium, gadolinium and terbium are used in energy-saving fluorescent lamps. The bulbs produce 70 percent less heat and are 70 percent more efficient at using electricity.

REE is used in metallurgy as an alloying agent in desulfurized steel, as a nodule agent in nodular cast iron, as a lighter flint, and as an alloying element to improve the properties of superalloys and magnesium, aluminum, and titanium alloys.

* Rare earth elements are used in the nuclear industry for control rods, thinners, shields, detectors and counters.

* Rare metals can reduce the friction of the power cord, thus reducing leakage.

Military applications of rare earth elements include:

Rare earths: gadolinium, samarium, yttrium are needed for RF circulators used in magneto-controlled radars and electronic signal streams in missiles for Patriot missile air defense systems.

Rare earths: dysprosium, erbium, europium, neodymium, praseodymium, terbium and yttrium for lasers and avionics terminals used in on-board systems such as tanks and armored vehicles.

Precision guided munitions (PGM) involve a variety of missiles, including cruise, anti-ship (ASM) and surface-to-air (SAM) as well as bunker busters, requiring rare earths: dysprosium, neodymium, praseodymium, samarium and terbium.

The guidance and control systems for missiles and bombs toward their targets require rare earths: terbium, dysprosium, samarium, praseodymium and neodymium.

High capacity power supplies, batteries and electronic jamming devices in electronic warfare require rare earth: yttrium iron garnet.

The permanent magnet motors in destroyers require rare earths: terbium, dysprosium, samarium, praseodymium and neodymium.

The F-22 Raptor and F-35 Lightning II stealth fighters use 6% rhenium in their engines, and erbium is also added to the vanadium steel. The electrical system in the aircraft uses samarium cobalt permanent magnets to generate electricity.

3. The importance of rare earths

The reason why people attach importance to rare earth is that each member of rare earth has its own characteristics, unique skills and unique abilities in the field of high-tech. For example, cerium alloy is resistant to high heat, which can be used to make jet propeller parts. As a glass additive, it can absorb ultraviolet and infrared rays. It can be applied to the catalyst of automobile exhaust purification, which can effectively prevent a large amount of automobile exhaust gas from being discharged into the air. For medical purposes, gadolinium's water-soluble paramagnetic complex improves human MRI signals; Thulium can be used as a source for portable medical X-ray machines to make portable blood radiographs, which emit X-rays that illuminate the blood and cause white blood cells to drop, thereby reducing early organ transplant rejection. Thanks to its high affinity for tumor tissue, thulium can also be used in the clinical diagnosis and treatment of tumors.

Scientists find new uses for rare earths almost every three to five years, and they are responsible for one out of every six inventions. In the process of steelmaking, adding just a small amount of rare earths can make otherwise fine steel "stronger" and increase its lifespan. In the military field, rare earth can greatly improve the alloy tactical performance of weapons and equipment, for example, in the Gulf War, the addition of rare earth lanthanum night vision became the source of overwhelming superiority of American tanks. In the field of nuclear energy, the rare earth element gadolinium and its isotopes are the most effective neutron absorbers, and can be used as a chain-reaction level inhibitor to control nuclear power plants, becoming the "safety god" of nuclear reactors. With the development of science and technology and the expansion and extension of rare earth science and technology, rare earth elements will have a broader utilization space.