TcSUH
Warning: Undefined variable $events_postname in /home1/tcsuh570/public_html/events_select2.php on line 105
Bi-Weekly Seminar
Electropolymerizable Dendrimer and Hybrid Nanomaterials
by: Prof. Rigoberto Advincula
Date: Friday May 08, 2009
Time: 12:00 pm – 1:00 pm
Location: Houston Science Center – Building 593 — Room 102
Overview
In this talk, we describe the investigation of dendrimeric precursor and hybrid nanomaterials towards the formation of conjugated polymer nanoparticles, networks, nanopatterning, and nanobjects. Electropolymerizable precursor polymer materials have been widely reported by our group and have been used to modify electrode surfaces with the formation of conjugated polymer network films. Most of these materials are based on linear polymers and block/graft copolymers. Very few reports have been given on dendritic precursor materials utilized for their electrochemical activity. In this talk, we will describe several strategies in which we have synthesized dendritic precursor polymers. These materials have applications for conducting polymer-based energy transfer materials, nanoelectronics, and sensing.
Download: Event PDF
Back to TcSUH News & Events
Bi-Weekly Seminar
Direct Probe of the Key Building Block of the Fe-based Superconductors with Scanning Tunneling Microscopy/Spectroscopy (STM/S)
by: Dr. Shuheng H. Pan
Date: Thursday April 23, 2009
Time: 12:00 pm – 1:00 pm
Location: Houston Science Center – Building 593 — Room 102
Overview
The recently discovered superconductivity in iron (Fe)-based compounds is another exciting advancement in condensed matter physics since the discovery of high-Tc superconductivity in cuprates. Using a UHV Low Temperature Scanning Tunneling Microscope, we have been studying the structural and electronic properties of the parent and Co-doped BaFe2As2 compound. We find that, by low temperature in situ cleaving, we are able to expose the key building block - the Fe-As layer of this compound, where superconductivity is believed to occur. With STM/S, we directly probe this key building block with spatial resolution down to atomic scale. STM is a surface sensitive technique. Keeping this in mind, I will demonstrate how we use this high real-space resolution and surface sensitive technique to learn the structural and electronic properties within the bulk. I will also discuss our results on the density-of-states (DOS) evolution with doping, the scaling of the superconducting energy gap, and some electronic local effects that may be used to help determine the pairing symmetry.
Download: Event PDF
Back to TcSUH News & Events
Bi-Weekly Seminar
Interface Engineered Nanostructural Metamaterials with Anomalous Physical Phenomena
Date: Tuesday April 14, 2009
Time: 12:00 pm – 1:00 pm
Location: Houston Science Center – Building 593 — Room 102
Overview
Interface engineered material has attracted more and more attention in the multifunctional materials research and active device fabrication. It plays a key role to control the physical properties of advanced nanomaterials and results in the discovery of various new physical phenomena with excellent opportunity for developing new metamaterials for active devices and engineered nanosystems. We have focused on the systematic studies on the formations and the characterizations of various highly epitaxial oxide thin films and multilayered layered structures to understand the nature of interface induced anomalous physical phenomena. Recently, by optimizing the epitaxial conditions we have successfully controlled and systematically investigated the highly epitaxial ferroelectric thin films and highly ionic conductive oxide thin films and the multilayered nanostructures. We have observed strong anisotropic phenomena in highly epitaxial (Pb,Sr)TiO3 thin films, and observed various anomalous physical phenomena such as locked ferroelectric domain formation from the multilayered BaTiO3/SrTiO3 superlattices for memory capacitance device and active actuator applications, extremely high ionic conductivity in the multilayered YSZ/GCO structures solid state fuel cells, and many others. Also, a series of models were developed to understand these interface phenomena. Details will be presented in the talk.
Download: Event PDF
Back to TcSUH News & Events
Bi-Weekly Seminar
Fe-As Based High-Temperature Superconductors: The Breakthrough of the Year (2008)
by: Bernd Lorenz
Date: Friday April 03, 2009
Time: 12:00 pm – 1:00 pm
Location: Houston Science Center – Building 593 — Room 102
Overview
The discovery of superconductivity in rare earth (R) oxypnictides, ROFeAs, by Hosono et al. has revived the field of high-temperature superconductivity. With transition temperatures of up to 55 K the new class of superconducting compounds has given hope to reach even higher Tc's exceeding those of the copper oxide superconductors. At the same time, questions have been raised concerning possible similarities and differences between the two high-Tc systems with the perspective that studying the FeAs superconductors might also help to better understand the cuprates. I will present a brief overview of some recent results and discuss examples of FeAs-based superconductors crystallizing in different basic structure types: (i) The PbFCl-type structure (LiFeAs) and (ii) the ThCr2Si2-type structure (AFe2As2, A=K, Rb, Cs, and the solid solution (K/Sr)Fe2As2). The ternary compounds are all self-doped superconductors. The (K/Sr)Fe2As2 - system reveals an interesting phase diagram that seems to be generic to most FeAs-systems, with a maximum Tc at an optimal composition and a spin density wave (SDW) state at the Sr-rich side. The extrapolation of the SDW phase boundary suggests the possible existence of a quantum critical point. Evidence for quantum critical scaling is found in resistivity and thermoelectric measurements.
Download: Event PDF
Back to TcSUH News & Events
Bi-Weekly Seminar
Electropolymerizable Dendrimer and Hybrid Nanomaterials
by: Prof. Rigoberto Advincula
Date: Thursday March 26, 2009
Time: 4:00 pm – 5:00 pm
Location: Houston Science Center – Building 593 — Room 102
Overview
In this talk, we describe the investigation of dendrimeric precursor and hybrid nanomaterials towards the formation of conjugated polymer nanoparticles, networks, nanopatterning, and nanobjects. Electropolymerizable precursor polymer materials have been widely reported by our group and have been used to modify electrode surfaces with the formation of conjugated polymer network films. Most of these materials are based on linear polymers and block/graft copolymers. Very few reports have been given on dendritic precursor materials utilized for their electrochemical activity. In this talk, we will describe several strategies in which we have synthesized dendritic precursor polymers. These materials have applications for conducting polymer-based energy transfer materials, nanoelectronics, and sensing.
Download: Event PDF
Back to TcSUH News & Events