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.