Future Directions in Rare Earth Research: Critical
Materials for 21st Century Industry
Thomas Lograsso Division of Materials Science &
EngineeringThe Ames Laboratory
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Research Opportunities• Separation and extraction
– Selective separation chemistry– Direct conversion from oxides– Recycling
• Improved processing– Selective separations– Energy efficient– Environmentally friendly– Nano-particulate processing
• Fundamental property and functionality– Fundamental chemistry/physics of 4f-3d electron interactions– New materials discovery – Substitution for RE
• RE reduction• RE-free
– Additives• Improved properties/performance
Historical Developments and Requirements
• Nd-Fe-B• Co added to
increase Tc• Add Dy to
increase anisotropy
• In a magnet for operation at 180 C, Dy is 70% of the materials cost
Research in Permanent Magnet Materials
• Performance– Higher energy products (new material discovery) – Better high temperature performance (substitution/additive)– Higher electrical resistivity (eddy current losses) (additive)– Enhanced mechanical properties (additive/processing)
• Cost– Raw materials costs
• Decrease or eliminate RE constituent(s) (new materials/nanoprocessing)
– Processing costs (direct conversion, selective separations)• Recycling
– Manufacturing scrap – swarf (processing/selective separations)– Post-consumer (processing)
Rare Earth Phosphors
Fig. 1. Emission spectrum of Y2O3:Eu. Fig. 4. Emission spectrum of Mg4GeO5.5F:Mn.
C.R. Ronda et al. / Journal of Alloys and Compounds 275 –277 (1998) 669 –676
Research in Phosphors• New phosphors
– high-efficiency optical transitions in non-rare-earth materials (new materials discovery)
– Lower dopant content (substitution?)
• Novel classes of wavelength conversion materials (downshifted LED or OLED emitters) for white light (new materials discovery
• Improved quantum efficiency / energy transfer (additives)• Nanoparticulate processing for shape/size control of
color
SUBSTITUTIONDifficult, if Not Impossible
Most critical applications – phosphors, magnetsDepends on the 4f electronic levels (each lanthanide is different) and crystal
environment Eu – color TV Nd – lasers Nd, Sm – permanent magents Tb – fiber optics La, Y, Gd – absence of 4f level – optical & electronic
Applications of unseparated rare earthsDepend upon the valence state and average atomic size of the rare earths in
the mixture petroleum cracking catalysts
alloy additives – Mg, Al, cast iron
Mixed valence applicationsCE(III)-CE(IV) – glass polishing, UV resistant glass, catalytic converters
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SUBSTITUTION/DISCOVERYYES or NO EXAMPLES
YESMischmetal for La in Ni metal hydride batteriesRouge (Fe oxides) for CeO2/Ce2O3 in glass polishing (However Ce is not in short supply – excess)
PARTIAL SUBSTITUTIONPr for Nd in NdFeB magnets; 4Nd atoms per 1Pr in original oreY – high temperature superalloys – used for ~30 years Al, Cr, could be utilized instead of Y
NO (People have been looking – but no luck) Eu – red color in TV; used for ~50 years, yet no substitute Nd – permanent magnets; used for ~27 years, , yet no substitute Sm – permanent magnets; used for over 30 years, , yet no substitute Ce – 3-way catalytic converters (automotive exhaust) – used for ~30 years – yet no
substitute
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SCIENTIFIC & ENGINEERING INFRASTRUCTURE
Training studentsundergraduate, graduate, post-doctorchem., chem. eng., mater. sci. & eng., physics
Research projects fundingNSF, DOE, DOD, NIST
National Research Center for Rare Earths and EnergyEducation institution with a strong tradition on REsLink with industrySubsidiary branches at other universitiesInternational collaborations
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