Today, let’s take a look at interesting facts about Yttrium and answer the following questions: “Why Is Yttrium Considered A Rare Earth Element?”, and “Why Is Yttrium Considered A Critical Raw Material?”

Why Is Yttrium Considered A Rare Earth Element?

Yttrium is considered a rare earth element despite not being a lanthanide due to its remarkably similar chemical and physical properties to the lanthanide elements. Yttrium (atomic number 39) shares chemical and physical similarities and has affinities with the lanthanides. This similarity is so pronounced that yttrium typically occurs in the same deposits as other REEs, making it naturally associated with the lanthanide group in geological settings.

The chemical basis for including yttrium with the rare earth elements lies in its ionic characteristics. Yttrium has a similar 3+ ion with a noble gas core and has both atomic and ionic radii similar in size to those of terbium and dysprosium. This means that despite having an atomic number of 39, yttrium’s ionic radius falls within the range of the heavy rare earth elements (HREEs), specifically between terbium (atomic number 65) and dysprosium (atomic number 66). This similarity in ionic size and charge allows yttrium to substitute for the heavier lanthanides in crystal structures, explaining why it is generally found in nature with lanthanides.

From a practical standpoint, yttrium is grouped with the heavy rare earth elements in classification systems. Yttrium, although light (atomic number 39), is included with the HREE group because of its common chemical and physical affiliations with the other HREEs. This classification makes sense given that yttrium’s abundance in the Earth’s crust is 33 parts per million, placing it within the range of other rare earth elements. For comparison, gadolinium has 6.2 ppm, terbium has 1.2 ppm, and dysprosium has 5.2 ppm.

The geological occurrence of yttrium further justifies its inclusion with the rare earth elements. The mineral xenotime (YPO4), a yttrium phosphate, is one of the principal ore minerals for rare earth elements. Because yttrium has similar charge and ionic radius to other HREEs, xenotime generally contains substantial amounts of the HREEs alongside yttrium. This co-occurrence in nature, combined with similar extraction and processing requirements, makes it practical to consider yttrium as part of the rare earth element group from both scientific and industrial perspectives. In nature, REEs do not exist individually but instead occur in minerals as either minor or major constituents, and yttrium consistently follows this pattern by occurring alongside the lanthanides in REE deposits.

Why Is Yttrium Considered A Critical Raw Material?

Yttrium is considered a critical raw material due to its essential role in numerous high-technology applications combined with significant supply chain vulnerabilities. As a heavy rare earth element, yttrium is fundamental to modern technologies including phosphors for LED lighting and displays, lasers, metal alloys, and various electronic components. The glass industry relies heavily on yttrium, with specific applications in optical glass where yttrium greatly increases the refractive index. Yttrium is irreplaceable in fiber-optic telecommunication cables, where erbium-doped fibers containing yttrium function as laser amplifiers, enabling long-distance signal transmission. Additionally, yttrium-aluminum-garnet (YAG) doped with cerium serves as the most common LED phosphor, while yttrium, europium, and terbium phosphors create the red-green-blue combinations used in many light bulbs, panels, and televisions.

The criticality of yttrium is amplified by severe supply concentration and geopolitical risks. Between 2011 and 2017, China produced approximately 84% of the world’s rare earth elements, with the United States contributing only about 4% of global supply during its limited production period from 2012-2015. China’s dominance extends beyond raw material production to processing capabilities, as nearly all REE separation and refining occurs within China. When China announced intentions to reduce REE exports in 2010 through quotas, licenses, and taxes, it sent shockwaves through industries dependent on these materials. The ion-adsorption clay deposits in southern China serve as the world’s primary source of heavy rare earth elements including yttrium, with these deposits being economically viable due to easy extraction methods despite relatively low concentrations of 0.03-0.2% REEs.

The strategic importance of yttrium extends to critical defense and clean energy applications. Yttrium is used in jet fighter engines, missile guidance systems, satellite power and communication systems, and various military electronic countermeasures. In clean energy technologies, yttrium is essential for wind turbine generators and electric vehicle components. The concentration of yttrium supply in China raises significant concerns for nations dependent on high-technology manufacturing. Expert panels convened by the National Research Council, U.S. Department of Energy, and European Commission have consistently ranked rare earth elements including yttrium as having high “criticality” – meaning they combine high technological and economic importance with high supply-side risk. The limited number of economically viable deposits (for example, only 6 of 500 known carbonatites are mined for REEs) and the complexity of REE separation processes further compound supply vulnerabilities.

The combination of yttrium’s irreplaceable properties in advanced technologies and its concentrated supply chain makes it a quintessential critical material. With yttrium’s crustal abundance at 33 parts per million and its occurrence primarily in deposits controlled by a single nation, any supply disruption could force significant changes in many technological aspects of modern society. The mineral xenotime (YPO4), a principal source of yttrium, typically contains the element alongside other heavy rare earth elements, making independent yttrium production challenging. Recovery efforts are further complicated by the need for sophisticated separation techniques to isolate individual rare earth elements from their naturally occurring mixtures. These factors – essential applications, limited substitutes, supply concentration, and processing complexity – collectively establish yttrium’s status as a critical raw material for advanced economies.

Interesting Facts About Yttrium

1. Yttrium is never found free in nature but always occurs in combination with lanthanide elements, despite not being a lanthanide itself – it’s actually a transition metal that behaves chemically like the rare earth elements.
2. The element has no known biological role in humans, yet yttrium compounds are used in cancer treatments – yttrium-90 is employed in radioimmunotherapy to treat liver cancer and non-Hodgkin’s lymphoma.
3. Yttrium oxide has one of the highest melting points of any compound at 2,425°C (4,397°F), making it valuable for high-temperature applications like jet engine coatings.
4. When alloyed with aluminum and garnet, yttrium forms YAG (yttrium aluminum garnet), which is used as a synthetic diamond simulant and in high-powered laser systems.
5. Yttrium barium copper oxide (YBCO) was the first material discovered to become superconducting above the boiling point of liquid nitrogen (77K), revolutionizing the field of high-temperature superconductors in 1987.
6. The element exhibits unusual magnetic properties – pure yttrium is paramagnetic above 1,500°C but becomes increasingly magnetic as temperature decreases.
7. Yttrium has only one stable isotope (Y-89), making it one of only 26 monoisotopic elements on the periodic table.
8. Despite its atomic number of 39, yttrium’s properties more closely resemble the heavier lanthanides (elements 57-71) due to the lanthanide contraction phenomenon.
9. Yttrium iron garnet (YIG) has the smallest magnetic damping of any known material, making it crucial for microwave and acoustic applications.
10. The element forms compounds in only one oxidation state (+3), unlike many transition metals that exhibit multiple oxidation states.
11. Yttrium oxide nanoparticles are transparent to visible light but strongly absorb ultraviolet radiation, making them useful in UV-blocking applications.
12. Natural yttrium is always radioactive due to trace amounts of yttrium-90, though the stable Y-89 isotope comprises 99.99% of natural samples.
13. Yttrium has an unusually low thermal neutron capture cross-section, making it valuable in nuclear reactor applications as it doesn’t readily absorb neutrons.
14. The element’s name comes from Ytterby, Sweden – a village that gave names to four elements (yttrium, ytterbium, terbium, and erbium), more than any other location.
15. Yttrium phosphors produce red color in LED lights and CRT television tubes – europium-activated yttrium compounds were crucial for color TV development.
16. The element has a unique crystal structure that transitions from hexagonal close-packed at room temperature to body-centered cubic at high temperatures.
17. Yttrium-stabilized zirconia has ionic conductivity at high temperatures, making it essential for oxygen sensors in automotive exhaust systems and fuel cells.
18. Pure yttrium metal oxidizes slowly in air at room temperature but can ignite spontaneously when finely divided or heated above 400°C.
19. Yttrium compounds show strong Lewis acidity, making them effective catalysts for organic polymerization reactions, particularly in producing polylactide plastics.
20. The element’s atomic radius is nearly identical to holmium’s, allowing complete solid solution between these elements – a rare occurrence for elements not adjacent on the periodic table.

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