A Look Inside the World of Chemistry: Developments and Applications of Yttrium

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Another major area of research and development involving yttrium is in the area of materials science, particularly in the development of superconductors. Superconductors are materials that, when cooled below a critical temperature, exhibit no resistance to electric current7. The earliest superconductors were metals and metal alloys, which had to be cooled using liquid helium or hydrogen to near-zero Kelvin. A breakthrough occurred with the discovery of the superconductive properties of yttrium barium copper oxide (YBCO), a ceramic material which was not expected to exhibit such behaviour. The researchers who made the discovery at IBM labs in Zurich were working towards a material based on just the first three compounds, only to discover that the sample, after being exposed to great heat, was “contaminated” by oxygen. Through a stroke of sheer luck they decided to test the contaminated ceramic material nonetheless, only to find that the material was superconductive and moreover, that its critical temperature for superconductive-behaviour was 90 K! This was unprecedentedly high, and provided a gateway for the application of superconducting materials in engineering and technology. Why? Because now superconductive materials could be developed that would work within the conditions of liquid nitrogen cooling, as liquid nitrogen has a boiling point of 77 K. Thus it was not possible to use a relatively cheap and abundant refrigerant as opposed to the very expensive liquid helium. This ceramic material can by synthesized via the following reaction8:

4 BaCO3 + Y2(CO3)3 + 6 CuCO3 + (1−x)/2 O2 → 2 YBa2Cu3O7−x + 13 CO2

One particular use of YBCO is in Maglev trains9. A Maglev train (abbreviated from “Magnetic levitation”) employs the use of the Meissner Effect to levitate the train above a magnetic track, achieving nearly zero friction as a result. The Meissner Effect is a characteristic of superconductors such as YBCO wherein a magnet becomes trapped within the magnetic field of the superconductor, “pinning” the magnet at one height relative to the superconductor9. The magnet can even be pinned into position from below the superconductor! In one particular design8, The superconducting YBCO plates are attached to the vehicle, cooled within a liquid nitrogen vessel, and levitated above a magnetic track. The advantages of such a vehicle design is that no controls for levitation or guidance are necessary, as the vehicle will simply follow a magnetic track and remain at a fixed height (so long as the material stays below its critical temperature, of course), and that no lubrication is required in such a design due to the incredibly low level of friction experienced by the vehicle being levitated this way.[pic 5][pic 6]

Another example of the use of YBCO superconductors is in the development of viable magnetic-sail spacecraft technology11. Magnetic-sails are a conceptual design for deep-space crafts that employ the use of solar winds- high energy plasmas emitted by the sun- to be converted into thrust, using YBCO-coated coils in order to transfer momentum from the solar winds to the vessel using the magnetic field produced from the coil. The thrust produced is in proportion to the magnetic moment, μ, of the coil. The YBCO-coated coil is currently the ideal candidate for such magnetic sails; with the large diameter and thin-walled structure of the coil described, the YBCO coil has the optimal magnetic moment with minimal hoop stress and maximized thermal stability. One ideal feature of a YBCO coil is that due to the cold environment of space (~20 K ) no refrigerant is needed to place the YBCO in a superconductive state- it is kept cool enough by its surroundings in this application.

Part of the beauty of the discovery of YBCO was its accidental nature, which is a common theme amongst some of the most amazing and revolutionary scientific leaps. The economically feasible use of superconductors was brought about by a whimsical test done by scientists who had considered themselves to have made some “mistake”, however that mistake resulted in an outcome which was miraculous and entirely unanticipated, and led to the incredible and diverse applications described above. Before this, it was believed that ceramic material could not possibly be superconductive. As it turns out, they happen to be some of the best and most useful superconductors currently known to exist.

I believe the example of Yttrium reveals much of the nature of scientific inquiry, and demonstrates the attractive and rewarding qualities that such work possesses. The famous biochemist and prolific author Isaac Asimov once said: “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘That’s funny…’” In both its very discovery as well as the development of YBCO superconductors, one can see the truth reflected in his words. Science leads us to discover things that we cannot even anticipate, and often those chance discoveries are some of the greatest and most ground-breaking, progressive discoveries to be made. It also demonstrates the utility and benefit of scientific study to society: in the applications of radioactive isotopes and the recent uses developed for YBCO such as Maglev transport systems and spacecraft propulsion mechanisms, the study and understanding of these compounds has come to benefit many through clever, creative applications of these compounds. And all of this is incredible work just a small fraction of that done on one of the 108 elements upon the periodic table. For each and every one there exists a equal- if not larger- body of research that is always expanding; with each question answered arises several more that need the attention of many bright, curious minds to grapple with them, so that further discoveries and developments such as those above can be made.

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Bibliography

- “Yttrium Element Facts”. http://www.chemicool.com/elements/yttrium.html

- “Blogging the Periodic Table” by Sam Kean. http://www.slate.com/articles/health_and_science/elements/features/2010/blogging_the_periodic_table/ytterby_the_tiny_swedish_island_that_gave_the_periodic_table_four_different_elements.html

- “Abundance of Elements in Earth’s Crust”. http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth's_crust

- “Beta: More Information” http://www.darvill.clara.net/nucrad/morebeta.htm

- “Y-90 liver cancer-busting treatment: Safe, fast, extends life, study finds”. http://www.sciencedaily.com/releases/2011/03/110328092409.htm

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