🎯 Terras-Raras
Em poucas palavras
Grupo de 17 elementos químicos (15 lantanídeos mais escândio e ítrio) conhecidos por suas propriedades magnéticas e condutoras únicas, fundamentais para a indústria de alta tecnologia.
📝 Notas e Desenvolvimento
- São chamados de “raros” não pela escassez na crosta terrestre, mas pela dificuldade técnica de encontrá-los em concentrações economicamente viáveis e pelo complexo processo de separação química.
- Possuem importância estratégica global, sendo componentes indispensáveis na fabricação de superímãs, baterias de veículos elétricos, turbinas eólicas e smartphones.
- A mineração e o processamento desses elementos envolvem desafios ambientais significativos devido à geração de resíduos tóxicos e, por vezes, radioativos.
Resumo dos Elementos
| Z | Symbol | Name | Etymology | Selected applications | Abundance23(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-24)[[24]]\(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-25) (ppmb(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-26)) |
|---|---|---|---|---|---|
| 21 | Sc | Scandium | from Latin Scandia (Scandinavia). | Light aluminium-scandium alloys for aerospace components, additive in metal-halide lamps and mercury-vapor lamps,25(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-CRC\_ed89\_elements-27) radioactive tracing agent in oil refineries | 22 |
| 39 | Y | Yttrium | after the village of Ytterby, Sweden, where the first rare-earth ore was discovered. | Yttrium aluminium garnet (YAG) laser, yttrium vanadate (YVO4) as host for europium in television red phosphor, YBCO high-temperature superconductors, yttria-stabilized zirconia (YSZ) (used in tooth crowns; as refractory material - in metal alloys used in jet engines, and coatings of engines and industrial gas turbines; electroceramics - for measuring oxygen and pH of hot water solutions, i.e. in fuel cells; ceramic electrolyte - used in solid oxide fuel cell; jewelry - for its hardness and optical properties; do-it-yourself high temperature ceramics and cements based on water), yttrium iron garnet (YIG) microwave filters,25(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-CRC\_ed89\_elements-27) energy-efficient light bulbs (part of triphosphor white phosphor coating in fluorescent tubes, CFLs and CCFLs, and yellow phosphor coating in white LEDs),26(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-28) spark plugs, gas mantles, additive to steel, aluminium and magnesium alloys, cancer treatments, camera and refractive telescope lenses (due to high refractive index and very low thermal expansion), battery cathodes (LYP) | 33 |
| 57 | La | Lanthanum | from the Greek “lanthanein”, meaning to be hidden. | High refractive index and alkali-resistant glass, flint, hydrogen storage, battery-electrodes, camera and refractive telescope lenses, fluid catalytic cracking catalyst for oil refineries | 39 |
| 58 | Ce | Cerium | after the dwarf planet Ceres, named after the Roman goddess of agriculture. | Chemical oxidizing agent, polishing powder, yellow colors in glass and ceramics, catalyst for self-cleaning ovens, fluid catalytic cracking catalyst for oil refineries, ferrocerium flints for lighters, robust intrinsically hydrophobic coatings for turbine blades27(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-29) | 66.5 |
| 59 | Pr | Praseodymium | from the Greek “prasios”, meaning leek-green, and “didymos”, meaning twin. | Rare-earth magnets, lasers, core material for carbon arc lighting, colorant in glasses and enamels, additive in didymium glass used in welding goggles,25(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-CRC\_ed89\_elements-27) ferrocerium firesteel (flint) products, single-mode fiber optical amplifiers (as a dopant of fluoride glass) | 9.2 |
| 60 | Nd | Neodymium | from the Greek “neos”, meaning new, and “didymos”, meaning twin. | Rare-earth magnets, lasers, violet colors in glass and ceramics, didymium glass, ceramic capacitors, electric motors in electric automobiles | 41.5 |
| 61 | Pm | Promethium | after the Titan Prometheus, who brought fire to mortals. | Nuclear batteries, luminous paint | 1×10−1528(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-30)[[c]]\(https://en.wikipedia.org/wiki/Rare-earth\_element#cite\_note-31) |
| 62 | Sm | Samarium | after mine official, Vasili Samarsky-Bykhovets. | Rare-earth magnets, lasers, neutron capture, masers, control rods of nuclear reactors | 7.05 |
| 63 | Eu | Europium | after the continent of Europe. | Red and blue phosphors, lasers, mercury-vapor lamps, fluorescent lamps, NMR relaxation agent | 2 |
| 64 | Gd | Gadolinium | after Johan Gadolin (1760–1852), to honor his investigation of rare earths. | High refractive index glass or garnets, lasers, X-ray tubes, computer bubble memories, neutron capture, MRI contrast agent, NMR relaxation agent, steel and chromium alloys additive, magnetic refrigeration (using significant magnetocaloric effect), positron emission tomography scintillator detectors, a substrate for magneto-optical films, high performance high-temperature superconductors, ceramic electrolyte used in solid oxide fuel cells, oxygen detectors, possibly in catalytic conversion of automobile fumes. | 6.2 |
| 65 | Tb | Terbium | after the village of Ytterby, Sweden. | Additive in neodymium based magnets, green phosphors, lasers, fluorescent lamps (as part of the white triband phosphor coating), magnetostrictive alloys such as terfenol-D, naval sonar systems, stabilizer of fuel cells | 1.2 |
| 66 | Dy | Dysprosium | from the Greek “dysprositos”, meaning hard to get. | Additive in neodymium based magnets, lasers, magnetostrictive alloys such as terfenol-D, hard disk drives | 5.2 |
| 67 | Ho | Holmium | after Stockholm (in Latin, “Holmia”), the native city of one of its discoverers. | Lasers, wavelength calibration standards for optical spectrophotometers, magnetic fields,permanent magnets. | 1.3 |
| 68 | Er | Erbium | after the village of Ytterby, Sweden. | Infrared lasers, vanadium steel, fiber-optic technology | 3.5 |
| 69 | Tm | Thulium | after the mythological northern land of Thule. | Portable X-ray machines, metal-halide lamps, lasers | 0.52 |
| 70 | Yb | Ytterbium | after the village of Ytterby, Sweden. | Infrared lasers, chemical reducing agent, decoy flares, stainless steel, strain gauges, nuclear medicine, earthquake monitoring | 3.2 |
| 71 | Lu | Lutetium | after Lutetia, the city that later became Paris. | Positron emission tomography – PET scan detectors, high-refractive-index glass, lutetium tantalate hosts for phosphors, catalyst used in refineries, LED light bulb | 0.8 |
🔗 Conexões e Contexto
- Atlas: MdC - Tecnologia
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🎯 Terras-Raras
Em poucas palavras
Grupo de 17 elementos químicos (15 lantanídeos mais escândio e ítrio) conhecidos por suas propriedades magnéticas e condutoras únicas, fundamentais para a indústria de alta tecnologia.