The search for materials with desired properties concomitantly relies on the discovery of new materials and the subsequent growth of large single crystals. To unequivocally determine the material's innate properties, large single crystals must be grown such that detailed studies can be completed. The growth of high quality single crystalline materials allows the determination of intrinsic properties and for fundamental correlation between structures and unusual magnetic and electrical properties. This research, supported by the Solid State and Materials Chemistry program is focused on synthesizing materials of the ternary intermetallics Ln:M:X (Ln = lanthanide, M = transition metal, X = Al, In) to correlate crystal chemistry and physical properties. The effort is focused on growing high quality single crystals of four families of intermetallics to study the competition of magnetic fluctuations and unusual magnetism, targeting the CeCr2Al20, Ho6Mo4Al43, ThMn12, and YbFe2Al10 structure types. These structures consist of high coordination polyhedra and serve as models for investigating the role of two sublattices and packing on magnetism.
NON-TECHNICAL SUMMARY: The search for materials with desired properties concomitantly relies on the discovery of new materials and systems. The proposed work, supported by the Solid State and Materials Chemistry program involves the synthesis and characterization of novel materials containing rare earth transition metals to understand new physical phenomena. The group's effort is aimed at growing large single crystals to perform measurements and determine intrinsic behavior of new compounds with potential energy applications. The PI's group will continue collaborations with scientists in Japan as there is a natural and mutually beneficial synergy of synthesis and characterization that exists between research groups, as well as a common mentoring of graduate and undergraduate students between the research groups. Research and teaching are integrated by incorporating crystallography and materials science throughout two courses (General Chemistry and Advanced Inorganic Chemistry). The partnership with a local elementary school will lead to continued enhancement in curriculum development. The Chan group will continue to develop hands-on materials-related demonstrations for incorporation into LSU Chem Demo program. An additional aim of this proposal is to involve high school chemistry and physics teachers for a summer research experience in the laboratory. This will offer an invaluable tool to boost teachers' involvement in the sciences and their understanding of how their discipline relates to the children in the classroom.
This research proposal is focused on synthesizing ternary intermetallics Ln:M:X (Ln = lanthanide, M = transition metal, X = Al, In) to correlate crystal chemistry and physical properties. We discovered many new intermetallics and published ~ 41 peer-reviewed articles in the last 3 years in physics (Phys. Rev. Lett., Phys. Rev. B, and J. Phys. Cond. Matt.) and chemistry journals (Chem. Mater., Inorg. Chem., JACS, J. Solid State Chem.), in addition to 4 submitted (in review stage). We have grown and characterized high quality single crystals of four families of intermetallics (CeCr2Al20, Ho6Mo4Al43, ThMn12, and YbFe2Al10 structure types) to study the competition of magnetic fluctuations and other unusual magnetism. These structure types consist of high coordination polyhedra and serve as models for investigating the role of two sublattices and packing on magnetism. During the course of this grant cycle, we mapped out the synthetic parameters to prepare single crystals of compounds adopting the ThMn12, CaCr2Al10, YbFe2Al10, Yb6M4Al43, LnM2Al20, and Ln2Ru3Al15 structure types. We have successfully grew single crystals of several new intermetallics during this reporting period. Intermetallic phases exhibit a rich range of chemical and physical properties, but a limiting factor in developing these compounds into useful materials is our inability to control their crystal structures to optimize their properties. One highlight is our recent paper "Filling in the holes: Structural and magnetic properties of the chemical pressure stabilized LnMnxGa3 (Ln = Ho-Tm; x < 0.15)", where we described a joint experimental and DFT-Chemical pressure analysis of a potential model system for chemically tunable intermetallic phases: compounds adopting the well-known AuCu3 structure type, whose magnetic properties can be modulated through the incorporation of transition metal guest atoms. The results of this work demonstrate the ability of the guest atoms to substantially alter stability and the magnetic properties of the phases, and reveal the driving forces leading to guest atom incorporation by these structures, which may be useful in the future design of magnetic materials. 10 Ph.D. students were supported over this grant cycle. Seven graduate and 6 undergraduate students also completed their degrees and have secured positions. All students presented their work at regional, national, and/or international conferences and several attended workshops (UCSB Summer School, neutron and synchrotron schools at NIST, ANL, and SNS). During this grant period, we began a productive collaboration to perform Mössbauer measurements and recently reported our work on Fe-doped LnM2Al20. Students in our group will continue to perform physical property measurements with physics colleagues, characterize single crystals at Oak Ridge National Laboratory TOPAZ beam line (first extended solids measured and published), collect powder diffraction data at APS, and measure low-temperature properties at Rice and University of Tokyo as needed. All students were active in K-12 outreach activities and plan to continue performing demonstrations to the community.
