Bryan Chakoumakos

Bryan Chakoumakos

Position: Instrument Scientist

Beamline: HB-3A

Instrument: Four-Circle Diffractometer

Group: Structure of Matter

Facility: Spallation Neutron Source

Email: chakoumakobc@ornl.gov

Phone: (865) 621-0227

Bryan Chakoumakos is a Distinguished Research Scientist in the Neutron Scattering Division at Oak Ridge National Laboratory (ORNL), where he conducts research on properties of novel and technologically important materials. He employs crystallography and X-ray/neutron diffraction methods and broadly publishes in physics, materials science, chemistry, and mineralogy. He received his Ph.D. in Geological Sciences (mineralogy & crystallography emphasis) at Virginia Tech in 1984, working with Gerry Gibbs.  In 1984-1987 he was a post-doctoral fellow at the University of New Mexico working with Rod Ewing.  He joined ORNL in 1987 initially working in the Solid State Division with Lynn Boatner.  After changing to the Neutron Scattering Group in 1993, he variously has been an instrument scientist for the powder diffractometer and the four-circle diffractometer at the High Flux Isotope Reactor (HFIR), and Group Leader for 11 years for diffraction groups involving instruments at HFIR and the Spallation Neutron Source. He currently is the Leader for the Single-Crystal Neutron Diffraction Team in the Neutron Diffraction Group.  He is Fellow of the Mineralogical Society of America (2007), the American Crystallographic Association (2016), and the American Association of the Advancement of Science (2016). He received the Bau Neutron Diffraction Award in 1992 from the American Crystallographic Association.  He served as Associate Editor (1999-2004) and Letters Editor (2005-2010) for the American Mineralogist and was also a Guest Editor of a special issue on Clathrate Hydrates, American Mineralogist, vol 89 (8-9), 2004.  He served as Secretary of the Mineralogical Society of America (2015-2019). Other activities include serving on the board of Scientific Directors for the National School on Neutron and X-ray Scattering (2008-2018) and the Intense Pulsed Neutron Source Program Advisory Committee (1996-2001). He has past chaired the Neutron Scattering (2001) and Powder Diffraction (2005) Special Interest Groups of the American Crystallographic Association.  He is a member of the Research Committee for the Japan Atomic Energy Agency - U.S. Department of Energy Cooperative Program on Neutron Scattering. 

Education

PhD in Geological Sciences (mineralogy & crystallography) at Virginia Tech

Research

Dr. Chakoumakos studies structure property relationships in technological and natural materials and the synthesis, crystal growth, and characterization of novel materials. He employs crystallography, mineralogy, and single-crystal and powder diffraction methods.

Selected Publications

B.C. Chakoumakos, R. Custelcean, J. O. Ramey, J. A. Kolopus, Rongying Jin, J.S. Neal, D.J. Wisniewski, and L.A. Boatner, Cerium chloride – methanol adduct crystals, CeCl3(CH3OH)4: preparation, crystallography, and scintillation properties, Crystal Growth & Design 8 2070-2072 (2008)

B.C. Chakoumakos and B.C. Sales, Crystal structure response in filled skutterudites, Journal of Alloys and Compounds 407 87-93 (2006)

B.C. Chakoumakos, C.J. Rawn, A.J. Rondinone, L.A. Stern, S. Circone, S.H. Kirby, Y. Ishii, C.Y. Jones, B.H. Toby, and D.C. Dender, Temperature dependence of polyhedral cage volumes in clathrate hydrates, Canadian Journal of Physics 81 183-189 (2003)

B.C. Chakoumakos, B.C. Sales, D. Mandrus, and G.S. Nolas, Structural disorder and thermal conductivity of the semiconducting clathrate Sr8Ga16Ge30, Journal of Alloys and Compounds 296 80-86 (2000)

B.C. Sales, B.C. Chakoumakos, D. Mandrus, and J.W. Sharp, Atomic displacement parameters and the lattice thermal conductivity of clathrate-like thermoelectric compounds, Journal of Solid State Chemistry 146 528-532 (1999)

B.J. Kennedy, C.J. Howard, and B.C. Chakoumakos, Phase transitions in perovskite at elevated temperatures - a powder neutron diffraction study, Journal of Physics, Condensed Matter 11 1479-1488 (1999)

V. Keppens, D. Mandrus, B.C. Sales, B.C. Chakoumakos, P. Dai, R. Coldea, M.B. Maple, D.A. Gajewski, E.J. Freeman, and S. Bennington, Localized vibrational modes in metallic solids, Nature 395 876-878 (1998)

B.C. Sales, D. Mandrus, B.C. Chakoumakos, V. Keppens and J. R. Thompson, Filled skutterudite antimonides: Electron crystal and phonon glasses, Physical Review B 56 15081-15089 (1997)

D.P. Norton, B.C. Chakoumakos, J.D. Budai, D.H. Lowndes, B.C. Sales, J.R. Thompson, and D.K. Christen, Superconductivity in SrCuO2/BaCuO2 superlattices: Formation of artificially-layered super-conducting materials, Science 265 2074-2076 (1994)

B.C. Chakoumakos, M.A. Abraham, and L.A. Boatner, Rietveld structure refinements of zircon-type MVO4 (M = Sc, Y, Ce, Pr, Tb, Ho, Er, Tm, Yb, Lu) using neutron diffraction data, Journal of Solid State Chemistry 109 197-202 (1993)

B.C. Chakoumakos and G.R. Lumpkin, Pressure-temperature constraints on the crystallization of the Harding pegmatite, Taos County, New Mexico, Canadian Mineralogist 28 287-298 (1990)

B.C. Chakoumakos, T. Murakami, G.R. Lumpkin, and R.C. Ewing, Alpha-decay induced fracturing in zircon: the transition from the crystalline to the metamict state, Science 236 1556-1559 (1987)

B.C. Chakoumakos, Systematics of the pyrochlore structure type, ideal A2B2X6Y, Journal of Solid State Chemistry 53 120-129 (1984)

Awards, Honors and Memberships

Bau Neutron Diffraction Award from the American Crystallographic Association (2019)