P. Shiv Halasyamani

P. Shiv Halasyamani
Associate Professor
	Office: 12 SR-1 Phone: (713) 743-3278 Email: psh at uh.edu Education B.S., University of Chicago, 1992 Ph.D., Northwestern University, 1996 Postdoctoral Fellow, Oxford University, 1997-1998 Honors, Fellowships, etc. Junior Research Fellow, Oxford University: 1998-2000 NSF Early Faculty CAREER Award: 2001-2006 Beckman Young Investigator: 2002-2005 ExxonMobil Solid-State Faculty Award: 2003 Award for Excellence in Research and Scholarship: 2004 Editorial Advisory Board: Inorganic Chemistry (2007 - Present) Materials Research Bulletin (2008 - Present) Award for Excellence in Research and Scholarship: 2009

Research Interests

      Synthetic solid-state chemistry, structure-property relationships, nonlinear optics, ferroelectrics, piezoelectrics
     A broad area that we are exploring is the synthesis and characterization of new non-centrosymmetric (NCS) oxides. NCS materials possess a host of interesting symmetry dependent properties, including chirality, ferroelectricity, and non-linear optical behavior (frequency doubling, i.e. SHG) - see the figure below. In order to ascertain if there are common features in NCS oxides we reviewed these materials, and determined the influence of a SOJT distortion. With respect to crystal chemistry, SOJT distortions are observed in oxide environments of d⁰ transition metals, e.g. Ti⁴⁺, Nb⁵⁺, and W⁶⁺ and cations with non-bonded electron pairs, e.g. Sn²⁺, Sb³⁺, and Te⁴⁺. We are interested in utilizing this distortion toward the synthesis of new ferroelectric-SHG oxide materials. We utilize a range of diffraction (powder and single crystal X-ray) and non-diffraction (TG/DTA and powder-SHG) measurements to characterize the materials. We have synthesized several SHG active materials, many with efficiencies of > 400 x SiO₂.
     We are expanding this area of research to include ferroelectric, piezoelectric, and pyroelectric measurements. We have recently discovered a series of new tungsten-bronze type oxides that exhibit SHG and ferroelectric behavior. We are currently examining their piezoelectric and pyroelectric behavior.

     Another research area we are investigating is the synthesis of new materials utilizing supercritical hydrothermal techniques. Here we are using both acidic and basic media to synthesize the new materials. In using this technique, we have discovered a new family of open-framework oxides that are related to the tellurite mineral Zemannite. Experiments indicate ion-exchange and reversible hydration properties.

Recent Publications

Chang, H.Y, Kim, S.H., Halasyamani, P.S., and Ok, K.M., Alignment of Lone-Pairs in a New Polar Material: Li₂Ti(IO₃)₆ – Synthesis, Characterization, and Functional Properties, J. Am. Chem. Soc., 131, 2426, 2009.

Frau, A., Kim, J.H., and Halasyamani, P.S., Na₃Ga₃Te₂O₁₂: Synthesis, Single Crystal Structure and Characterization, Solid State Sci., 10, 1263, 2008.

Chang, H.Y., Sivakumar, T., Ok, K.M., and Halasyamani, P.S., Polar Hexagonal Tungsten Bronze-type Oxides: KNbW₂O₉, RbNbW₂O₉, and KTaW₂O₉, Inorg. Chem. 47, 8511, 2008. [Preface: Overview of the Forum on Functional Inorganic Materials, P. Shiv Halasyamani and Kenneth R. Poeppelmeier, pp 8427 – 8428.]

Kim, Y., Seo, I-s., Baek, J., Halasyamani, P. S., and Martin, S. W., New Infrared Nonlinear Optical Crystal, LiGaGe₂S₆: Second-Harmonic Generation with High Laser Damage Threshold, Chem. Mater., 20, 6048, 2008.

Pan, S., Smit, J.P., Marvel, M. R., Stampler, E.S., Haag, J.M., Baek, J., Halasyamani, P.S., and Poeppelmeier, K.R., Synthesis, crystal structure, and nonlinear optical properties of Bi₂Cu₅B₄O₁₄, J. Solid State Chem., 181, 2087, 2008.

Kim, J. H. and Halasyamani, P.S., A Rare Multi-Coordinate Tellurite, NH₄ATe₄O₉ . 2H₂O (A = Rb or Cs): The Occurence of TeO₃, TeO₄, and TeO₅ polyhedra in the same material, J. Solid State Chem. 181, 2108, 2008.

Chang, H. Y., Ok. K. M., Kim, J. H., Stoltzfus, M., Woodward, P., and Halasyamani, P.S., Synthesis, Structure, Characterization, and Calculations of Two New Sn²⁺-W⁶⁺-oxides, Sn₂WO₅ and Sn₃WO₆, Inorg. Chem., 46, 7005, 2007.

Ok, K.M., Chi, E.O., and Halasyamani, P.S. Bulk Characterization Methods for Noncentrosymmetric Materials: Second-Harmonic Generation, Piezoelectricity, Pyroelectricity, and Ferroelectricity, Chem. Soc. Rev., 35, 710-717, 2006.

Casanova, D., Llunell, M., Alemany, P., Alvarez, S., Ok, K.M., and Halasyamani, P.S. Distortions in Octahedrally Coordinated d⁰ Transition Metal Oxides – A Continuous Symmetry Measures Approach, Chem. Mater., 18, 3176-3183, 2006.