Bulk Structure and Structure-Property Relationships in Metal-Rich Intermetallics and Metal-Rich Solid-State Inorganic Compounds
Program Scope: The goal is to elucidate the atomic positions in complex metal-rich solids, and in some cases to understand how this structure relates to physical properties, such as thermoelectric or magnetocaloric properties.
Major Program Achievements:
(1) Toward quasiperiodicity in one-dimension: Exploration of the Zn1-xPdx binary system (0.15 ≤ x ≤ 0.25) identified a series of structures with unit cells showing two sides with common lengths and the third varying greatly, some with distances in excess of 100 Å. We could interpret these structures as intergrowths based on two different icosahedral blocks, and have developed an “algorithmic” method to prepare new structures that may lead to a one-dimensional quasiperiodic system. Four structures were solved using super-space group methods. Electron diffraction studies also show superstructures. These structures are related to the Hume-Rothery gamma-brasses, and similar behavior occurs in Mn1+δGa1-δ. (See also Electronic Stabilization)
(2) Itinerant icosahedral magnets: Crystalline CrGa, MnGa, FeGa and the new compounds CrxFe1-xGa (0 < x < 1) were identified, structurally characterized by X-ray and neutron diffraction, and studied for their magnetic properties. This isostructural series is a set of approximants for icosahedral quasicrystals rich in transition metals. There is a change from antiferromagnetic to ferromagnetic behavior along the binary sequence, while Cr and Fe order according to local magnetic exchange seen in MnGa. Mn1+δGa1-δ shows formation of the cubic gamma-brass type.
(3) Defect-driven distortions: Defect Heusler-type intermetallics in the Ti-Ni-Ga system show a new superstructure that creates linked icosahedra, and further establishes the relationship between bcc-type structures and icosahedral quasicrystals. Other phases in V-Co-Ga and Nb-Rh-Ga systems exist.
(4) Technique Development. A technique for performing high-temperature, single crystal X-ray diffraction of air-sensitive compounds was developed and applied to study the high-temperature phase changes in Gd5Si2Ge2 and related phases. The technique involves using silica capillaries with inserted silica rods and creating a small volume for a “getter.” Using this technique we have solved numerous problems in phase transitions associated with magnetic responsive materials, Gd5(SixGe1-x)4 and Gd5(GaxGe1-x)4.
(5) Phase Changes in “Zn13Sb10: Zn13Sb10 undergoes a solid-solid phase transition at 767 K and then decomposes into ZnSb and Sb before reaching its “melting temperature” of 841 K. The structure of Zn13Sb10 is characterized by disorder at many Zn sites and show two distinct phase transitions below room temperature. Characterization of its temperature-dependent physical properties corroborate the structural characterization.
Program Impact: This research continues a strong tradition within the Materials Chemistry Program at the Ames Laboratory of the discovery of new metal-rich phases, the delineation of their structure, as well as their structural variation with temperature and with conditions of formation.
Contact Information:
Gordon Miller
Selected Publications
| Gourdon, O.; Bud'ko, S. L.; Williams, D.; Miller, G. J. "Crystallographic, Electronic and Magnetic Studies of z2 -GaM (M = Cr, Mn, or Fe): From Antiferromagnetism to Ferromagnetism," Inorg. Chem. 2004, 43 , 3210-3218. | Reprint |
| Mozharivskyj, Yu.; Pecharsky, A. O.; Bud'ko, S. L; Miller, G. J. "A Promising Thermoelectric Material: Zn4Sb3 or Zn 6-gammaSb5 . Its Composition, Structure, Stability, and Polymorphs. Structure and Stability of Zn1-gammaSb," Chem. Mater. , 2004 , 16 , 1580-1589. | |
| Mozharivskyj, Y.; Pecharsky, A. O.; Pecharsky, V. K.; Miller, G. J.; Gschneidner, K. A., Jr. " Tracking and understanding the first-order structural transition in Er5Si4 ," Phys. Rev. B 2004 , 69 , 144102/1-144102/13. | Reprint |
| Avila, M. A.; Wu, Y. Q.; Condron, C. L.; Bud'ko, S. L.; Kramer, M.; Miller, G. J.; Canfield, P. C. "Anomalous temperature-dependent transport in YbNi 2 B 2 C and its correlation to microstructural features," Phys. Rev. B , 2004 , 69 , 205107/1-205107/7. | Reprint |
| Sebastian, S. E.; Yin, D.; Tanedo, P.; Jorge, G. A.; Harrison, N.; Jaime, M.; Mozharivskyj, Y.; Miller, G.; Krzystek, J.; Zvyagin, S. A.; Fisher, I. R. "High field behavior of the spin gap compound Sr 2 Cu(BO 3 ) 2 ," Phys. Rev. B , 2005 , 71 , 212405/1-212405/4. | Reprint |
| Mozharivskyj, Y., Pecharsky, A. O., Pecharsky, V.K., Miller, G. J. "On the High-Temperature Phase Transition of Gd 5 Si 2 Ge 2 ," J. Am. Chem. Soc. , 2005 , 127 , 317-324. | |
| Gourdon, O., Gout, D., Miller, G.J., "Electronic States of Intermetallic Compounds," in Encyclopedia of Condensed Matter Physics , Eds. G. Bassani, G. Liedl, P. Wyder, Elsevier, Amsterdam, Netherlands, 2005 , pp. 409-422. | |
| Gemmill, W.R., Smith, M.D., Mozharivsky, Y.A., Miller, G. J., zur Loye, H.-C., "Crystal Growth, Structural Transitions and Magnetic Properties of the Fluorite-Related Osmates: Sm3OsO7 , Eu3OsO7 , and Gd3OsO7 ," Inorg. Chem. 2005 , 44 , 7047-7055. | Reprint |
| Gourdon, O., Izaola, Z., Elcoro, L., Petricek, V., Miller, G. J., "Zn1-x Pdx (x = 0.14 to 0.24): A Missing Link between Intergrowth Compounds and Quasicrystal Approximants," Philos. Mag. 2006 , 86 , 419-425 . | |
| Mozharivskyj, Y., Janssen, Y., Harringa, J. L., Kracher, A., Tsokol, A. O., Miller, G. J., "Zn13Sb10 : A Structural and Landau Theoretical Analysis of Its Phase Transitions," Chem. Mater. , 2006 , 18 , 822-831. | |
| Mozharivskyj, Y., Tsokol, A. O., Miller, G. J., "Structural Variations in Gd5Si4 - xSnx : Size vs. Electronic Effects," Z. Kristallogr. , 2006 , 221 , 493-501. | |
| Gourdon, O. and Miller, G. J., "Intergrowth Compounds in the Zn-rich Zn-Pd System: Towards 1D Quasicrystal Approximants," Chem. Mater. , 2006 , 18 , 1848-1856. | |
| Miller, G.J., "Rare-Earth Tetrelides, RE5(Si, Ge)4 : Materials for Magnetic Refrigeration," Chem. Soc. Rev. 2006 , 35 , 799-813. | |
| Misra, S. and Miller, G. J., "On the Distribution of Tetrelide Atoms (Si, Ge) in Gd5(SixGe1 - x)4 ," J. Solid State Chem. 2006 , 179 , 2290-2297. | Reprint |
| Erickson, A. S.; Misra, S.; Miller, G. J.; Gupta, R. J.; Schlesinger, Z.; Harrison, W. A.; Fisher, I. R., "Ferromagnetism in the Mott Insulator Ba 2 NaOsO 6 ," Phys. Rev. B 2006 , submitted for review. | |
| Miller, G.J., "The Coloring Problem in Solids: Implications for Structures and Properties," Z. Anorg. Allg. Chem. 2006 , 632 , 2078. | |
| Gourdon, O.; Gout, D.; Williams, D.J.; Proffen, T.; Hobbs, S.; Miller, G.J. "Atomic Distributions in the g -Brass Structure of the Cu-Zn System: A Structural and Theoretical Study," Inorg. Chem. 2006 , accepted for publication. | |
| Tkachuk, A.V.; Mozharivskyj, Yu., Mar, A. "Low- and High-Temperature Structures of YbCuBi," Z. Kristallogr. 2006 , 221 ,539-542. |
Materials Chemistry and
Biomolecular Materials Program
Ames Laboratory
Iowa State University
142 Spedding Hall
Ames, IA 50011 USA
Phone: 1.515.294.7568
FAX: 1.515.294.4709
