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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