Subramanian, Mas

Signature Faculty Fellow, Oregon Nanoscience and Microtechnologies Institute (ONAMI)

Education:
B.S. University of Madras, India (1975)
M.S. University of Madras, India (1977)
Ph.D. Indian Institute of Technology, Madras, India (1981)
Post-Doctoral Fellow, Texas A&M University (1982-84)

Awards:
DuPont Charles Pedersen Medal Award for Excellence in Scientific and Technical Achievement (2004)
Ralf Busch Materials Science Seminar Award, OSU (2007)

Research Group Web Site  

Research Interests: Materials Chemistry

Our research efforts focus on designing new inorganic solid state functional materials for emerging applications in electronics, solid-state energy conversion and other areas. In this quest, we rely on rational design of solids through fundamental understanding of crystal structure/property relationships as well as empirical and theoretical models. We are particularly inspired by the challenges involved in developing design concepts for functional materials with conflicting or "contraindicating" property requirements as seen in thermoelectrics, multiferroics, temperature independent high K dielectrics and materials exhibiting negative thermal expansion.

Our synthetic strategies extend beyond making bulk solid-state materials (single-crystals and ceramics), to building nanoparticulates and self-assembled nanostructures from solutions, solvothermal/hydrothermal methods and other 'bottom-up' synthetic routes.

Our work has resulted in many breakthrough discoveries. Some recent examples are: temperature independent colossal dielectrics (e.g. CaCu₃Ti₄O₁₂), ferromagnetic semiconductors with a Curie temperature close to room temperature (e.g. La₂NiMnO₆), a giant magnetodielectric response at room temperature in LuFe₂O₄, high ZT thermoelectric materials based on skutterudites with indium "rattlers" (e.g. In_0.2Co₃Sb₁₂) for converting waste-heat to electricity, and a "greener" synthetic route for hydrofluorocarbons via rationally designed inorganic fluorides.

Representative Publications

• Bi_2/3Ce_1/3Rh₂O₅: A New Mixed-Valent Rh Oxide with Hitherto Unknown Structure, J Solid State Chem., 2008, 181 (1), 56-60.
• Partial Charge Ordering in the Mixed-Valent Compound (Bi₆O₅)Rh₈³⁺Rh₄⁴⁺O₂₄, J Solid State Chem., 2007, 180 (12), 3463-3468.
• First Principles Investigation of the Electronic Structure of La₂MnNiO₆: An Insulating Ferromagnet, J. Mag. Mag. Mat., 2007, 308 (1), 116-119.
• Structural Model of Planar Defects in CaCu₃Ti₄O₁₂ Exhibiting a Giant Dielectric Constant, Chem. Mater., 2006, 18 (14), 3257-3260.
• Thermoelectric Properties of La_1-xA_xCoO₃ (A=Pb, Na), Solid State Sciences, 2006, 8 (5), 467-469.
• Thermoelectric Properties of Indium-Filled Skutterudites, Chem. Mater., 2006, 18 (3), 759-762.
• Magnetocapacitance and Magnetoresistance Near Room Temperature in a Ferromagnetic Semiconductor: La₂NiMnO₆, Advanced Materials, 2005, 17 (18), 2225-2227.
• A Novel Route to Toluene-Soluble Magnetic Oxide Nanoparticles: Aqueous Hydrolysis Followed by Surfactant Exchange, Chem. Mater., 2004, 16 (1), 118-124.
• Magnetodielectric Effects from Spin Fluctuations in Isostructural Ferromagnetic and Antiferromagnetic Systems, Phys. Rev. Lett., 2003, 91, 257208.
• A “Greener” Synthetic Route for Fluoroaromatics via Copper (II) Fluoride, Science, 2002, 297 (5587), 1665.
• ACu₃Ti₄O₁₂ and ACu₃Ru₄O₁₂ perovskites: High dielectric constants and valence degeneracy, Solid State Sciences, 2002, 4 (3), 347-351.