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P. Shiv Halasyamani
Associate Professor and Graduate Chairman
Office: 12 SR-1
Phone: (713) 743-3278
Email: psh@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)


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
Sivakumar, T., Chang, H.Y., Baek, J., and Halasyamani, P.S., Two New Non-Centrosymmetric Polar Oxides: Synthesis, Characterization, Second-Harmonic Generating, and Pyroelectric Measurements on TlSeVO5 and TlTeVO5, Chem. Mater., 19, 4710-4715, 2007.

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, 7005-7011, 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., Halasyamani, P.S. Distortions in Octahedrally Coordinated d0 Transition Metal Oxides – A Continuous Symmetry Measures Approach, Chem. Mater., 18, 3176-3183, 2006.

Ok, K.M. and Halasyamani, P.S. Synthesis, structure, and characterization of a new one-dimensional tellurite phosphate, Ba2TeO(PO4)2, J. Solid State Chem., 179, 1345-1350, 2006.

Sivakumar, T., Ok, K.M., and Halasyamani, P.S. Synthesis, Structure, and Characterization of Novel Two- and Three-Dimensional Vanadates: Ba2.5(VO2)3(SeO3)4 • H2O and La(VO2)3(TeO6) • 3H2O, Inorg. Chem., 45, 3602-3605, 2006.

Chi, E., Ok, K.M., Porter, Y., and Halasyamani, P.S. Na2Te3Mo3O16: A New Molybdenum Tellurite with Second-Harmonic Generating and Pyroelectric Properties, Chem. Mater., 18, 2070-2074, 2006.

Ok, K.M. and Halasyamani, P.S., New Metal Iodates: Syntheses, Structures, and Characterizations of Noncentrosymmetric La(IO3)3 and NaYI4O12 and Centrosymmetric ß-Cs2I4O11 and Rb2I6O15(OH)2 • H2O, Inorg. Chem., 44, 9353, 2005.

Kim, Y., Martin, S.W., Ok, K.M., and Halasyamani, P.S., Synthesis of the Thioborate Crystal ZnxBa2B2S5+x (x ~ 0.2) for Second Order Nonlinear Applications, Chem. Mater., 17, 2046, 2005.

Muller, E.A., Cannon, R.J., Sarjeant, A.N., Ok, K.M., Halasyamani, P.S., and Norquist, A.J., Directed Synthesis of Noncentrosymmetric Molybdates, Cryst. Growth and Design, 5, 1913, 2005.

Ok, K.M. and Halasyamani, P.S., New Mixed-Metal Tellurites: Synthesis, Structure, and Characterization of Na1.4Nb3Te4.9O18 and NaNb3Te4O16, Inorg. Chem., 44, 3919, 2005.

Ok, K.M and Halasyamani, P.S., New d0 Transition Metal Iodates: Synthesis, Structure, and Characterization of BaTi(IO3)6, LaTiO(IO3)5, Ba2VO2(IO3)4 . (IO3), K2MoO2(IO3)3, and BaMoO2(IO3)4 • H2O, Inorg. Chem., 44, 2263, 2005.

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