Rare Earth Elements

Lanthanides, which occupy the elements from near the bottom of the Periodic Table (atomic numbers 57 to 71), and the metals scandium and yttrium, which often occur in the same ore deposits and have comparable chemical properties, are among the 17 rare earth elements (REEs). The lanthanides are split into two groups: light rare earth elements (LREE), which include lanthanum through europium, and heavy rare earth elements (HREE), which include gadolinium through lutetium and yttrium.

The most commercially important REE deposits are located in or connected to alkaline igneous rocks and carbonatite and are associated with magmatic processes. The geochemical features of the REEs meant that they were rarely found concentrated in economically exploitable ore deposits, and they were assumed to be "rare" despite the fact that we now know otherwise.

Initially, REEs piqued people's curiosity almost entirely for academic reasons. The new elements appeared to have little commercial or industrial applications, and extracting them from their ores was too costly to be economically viable on a large scale. However, since the mid-twentieth century, the REEs' distinctive chemical features have led to their widespread use in a variety of technological applications and a significant increase in their economic value.

When a miner in Ytterby, Sweden, discovered an uncommon black rock in 1788, he coined the name rare earth. The ore was given the names "rare" and "earth" since it had never been seen before and because "earth" was the 18th-century geology term for acid-soluble rocks. Johan Gadolin, a chemist, named this hitherto unknown "earth" yttria after the town where it was discovered in 1794. Mines in the area of Ytterby mined rocks over time, yielding four elements named after the town (yttrium, ytterbium, terbium, and erbium).

During the 19th century, identifying new elements was a renowned but controversial activity for European chemists. In 1803 and 1828, Jöns Jacob Berzelius isolated and called cerium and thorium, respectively. Carl Gustaf Mosander, a Swedish scientist, began carefully analyzing the mixed rare earths in 1839, discovering and naming lanthanum, erbium, and terbium. Spectroscopy was created by chemists Gustav Kirchhoff and Robert Bunsen in the second half of the 19th century as a technique for identifying elements by studying light spectra. Finding techniques to separate rare-earth atoms was a major challenge in rare earth chemistry, both then and now.

In 1880, Carl Auer von Welsbach was a student of Robert Bunsen, the inventor of the Bunsen burner, at Heidelberg University in Germany. Welsbach began working with rare earth elements while he was there. He demonstrated that didymium, previously assumed to be an element, was actually an alloy of two rare earth elements that he termed neodymium and praseodymium. Welsbach became the first person to establish a commercial use for rare earth elements as he shifted his focus to industrial issues.

He realized that the rare earth elements' incandescent qualities could be valuable. ("Incandescence" refers to the visible light that is emitted when a material is heated.) Welsbach created a gas mantle (lamp) that generated strong light and could be mass-produced using an incandescent substance. More than five billion mantles had been manufactured by 1935, but the lamps were difficult to light, and the mountains of rare earth debris left over after production were prone to catching fire. Welsbach discovered a means to alloy, or combine these rare earth wastes with iron, resulting in ferrocerium, a "flint stone" that lit when struck. This substance was commonly utilized in cigarette lighters and automotive ignition systems. The ore used to supply these rare earth elements came mostly from Brazil, India, and North Carolina (USA), resulting in the world's first rare earth element commerce.

Rare earths are vital materials that are used in a wide range of modern products. The following trends are expected to drive up demand for rare earths in the next years:

• Transition towards more renewable energy;
• Developments in consumer electronic technology;
• Low emission technology concepts;
• Progress in automotive and future mobility trends.

In important growing industries such as clean energy technology, automotive technology, and consumer electronics, rare earths enable and promote magnetic, optical, catalytic, and electrical applications. Additionally, through 2025 and beyond, the oil refining, healthcare, lighting, industrial, aerospace, and robotics industries are likely to contribute significantly to global rare earths demand. They are known as "the seeds of technology" in Japan and they are referred to as "technology metals" by the US Department of Energy. They enable the high-tech world we live in today, from the shrinking of electronics to the enablement of green energy and medical technologies, as well as the support of a wide range of critical telecommunications and defense systems. They are the elements that, due to their particular magnetic, phosphorescent, and catalytic capabilities, have become indispensable in our technological world.

Cerium is the 25th most prevalent element in the earth's crust, at 68 parts per million. Rare earth elements are relatively numerous in the planet's crust. As a result, it is as plentiful as copper. Rare earth elements are typically scattered due to their geochemical characteristics. This means they are not frequently discovered in dense enough clusters to be worth mining. Because of their rarity, these minerals are referred to as rare earths.

Rare earths are powerful reducing agents chemically. The majority of their compounds are ionic and have high melting and boiling temperatures. When rare earths are in their metallic state, they are soft, but those with a higher atomic number are harder. Rare earth elements combine with other metallic and non-metallic elements to generate compounds with distinct chemical properties. In many electrical, optical, magnetic, and catalytic applications, this makes them indispensable and non-replaceable. Under UV light, rare earth compounds are typically fluorescent, which can aid in their identification. Rare earths can also form hydrogen gas when they react with water or diluted acid.

With developments in atomic physics over the 20th century, rare earth elements gained a new scientific and later geopolitical significance. It was uncertain how many rare earth elements there might be due to the difficulty of isolating them from ore and one another. Using X-ray spectroscopy, British physicist Henry Moseley discovered 15 elements in the lanthanide series (atomic numbers 57 through 71) in 1913.