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Participating Host List for Summer 2012

Name and Contact Info Summer Research Project

Douglas A. Keszler
Oregon State University

Douglas.Keszler@oregonstate.edu
(541) 737-6736

Website

Title: Characterization of Hafnium Oxysulfate, Zirconium Oxysulfate, and Their Nanolaminates
Description: Hafnium oxysulfate (HafSOx) is a promising new material that has a diverse range of practical applications. Capacitors, field effect transistors, and photoresists for use in photolithography can be all be made using HafSOx. High-quality thin films of HafSOx are produced by aqueous based methods. We are interested in determining the role of coordination chemistry on film solubility, ion exchange to produce novel materials, and the role of composition on electrical and chemical properties. Investigations will also be performed to evaluate the potential of HafSOx and zirconium oxysulfate (ZrfSOx) and their nanolaminates as solid superacid catalysts.Detailed surface characterization of these materials is essential in order to better understand their physical and chemical properties and thus facilitate its use in next generation electronic devices and catalytic systems. Temperature programmed desorption, thermogravimetric analysis, secondary ion mass spectroscopy, and x-ray photoelectron spectroscopy will be the main techniques used to characterize thin films and nanolaminates to enhance the current knowledge of these materials.

David C. Johnson
University of Oregon

davej@uoregon.edu
(541) 346-4612

Website

 

Title: Synthesis and investigation of physical properties of extended inorganic solids. Project A.
Description: A Grand Challenge in chemistry is preparing extended solids with designed structures that have desired properties. We recently have shown that it is possible to prepare many compounds that do not exist on equilibrium phase diagrams. These compounds self-assembly from a designed layered reactant. These compounds include structural isomers - extended inorganic solids that consist of two crystallographically aligned constituents with structurally precise layering schemes and turbostratic disorder between the constituents. Our key hypothesis is that the compositional wavelength (λc) and the compositional waveform (what element is where) (ϖc) built into the modulated elemental reactant is sufficient to kinetically trap a desired solid that consists of a pattern of interwoven layers of two or more different structures that self-assembles from the precursor. Figure 2 shows that we are able to use this approach to successfully synthesize structural isomers - compounds with the same number structural units but a different connectivity. The three STEM Z-contrast images shown in Figure 1, for example, are 3 of the 5 isomers of Nb4Pb4Se12.This project seeks to understand how structure and properties evolve as a function of n, m and the ordering of layers in structural isomers. We will prepare these new isomers of [(PbSe)1+δ]m[NbSe2]n compounds, determine their structures and correlate structural distortions, related to the interplay between surface, interface and bulk free energies, with nanostructure. We will also correlate electrical and superconducting properties with nanostructure, measuring electrical properties to derive carrier concentrations and mobility. This is an exciting new area of research to explore

David C. Johnson
University of Oregon

davej@uoregon.edu
(541) 346-4612

Website

 

Title: Synthesis and investigation of physical properties of extended inorganic solids. Project B.
Description:
Do you want to make compounds that have never been made before? Researchers in my laboratory have discovered that a broad new class of materials can be systematically prepared with turbostratic disorder between crystallographically aligned constituents with a variety of different structure types. Figure 1 shows a STEM image of an example compound, [(PbSe)0.99]2[WSe2]1. We refer to this new state of matter – layered structures with in-plane crystallinity, chemically and structurally abrupt interfaces, layer-to-layer misregistration, and turbostratic disorder ¬– as ferecrystals (from Latin fere, meaning almost). We prepare these compounds using modulated elemental reactants – a synthesis technique developed in my laboratory that provides new parameters that can be used to control the kinetics of solid-state reactions, avoiding thermodynamically stable reaction intermediates. By controlling layer thicknesses, the ratio of layer thicknesses and the order of the layers we have shown that it is possible to prepare compounds that do not exist on equilibrium phase diagrams that form by self-assembly from the layered reactant. Our key hypothesis is that the compositional wavelength (λc) and the compositional waveform (what element is where) (ϖc) built into the modulated elemental reactant is sufficient to kinetically trap a desired solid that consists of a pattern of interwoven layers of two or more different structures. The targeted compounds must be at least local free energy minima, as illustrated in figure 2. Modulated elemental reactants can be designed to contain the correct ratio of atoms, the correct number of atoms to form a specific thickness of each substance, and a long range ordering that approximates that of the desired compound. This project seeks to understand how properties evolve as a function of n, m and the ordering of layers in structural isomers at each composition. We will use the [(PbSe)1+?]m[TiSe2]n compounds as a baseline for structure and property comparisons for the other targeted systems. We will compare the evolution of structural distortions between the [(PbSe)1+?]m[TiSe2]n and [(SnSe)1+?]m[TiSe2]n compounds, since SnSe does not exist with a rock salt structure as a binary compound but has a rock salt structure within ferecrystals, to explore the interplay between surface/interface and bulk free energies. We will seek to determine the m value where the SnSe reverts back to the bulk structure rather than adopting the rock salt structure. Synthesizing LaSe and CeSe containing compounds would permit us to examine the effect of charge transfer between constituents on structure and on physical properties, initially through comparing carrier concentrations for PbSe, SnSe, LaSe and CeSe containing ferecrystals with identical n and m values. We will also test the limit of stability of [MSe]m[TSe2]n compounds where M=Ce or La, as either large values of m or large m to n ratios may be unstable due to charge transfer between constituents.

David C. Johnson
University of Oregon

davej@uoregon.edu
(541) 346-4612

Website

 

Title: Synthesis and investigation of physical properties of extended inorganic solids. Project C.
Description:
The surprising discovery of superconductivity at 26 K in layered iron oxypnictides has reinvigorated research on high Tc superconductivity. In addition to the identification of a new class of high Tc candidate materials, the intriguing interplay of magnetism and superconductivity in these materials has raised new questions of fundamental physics. It is now accepted that the iron pnictide layers in these materials are of key importance to the observed superconductivity. Shortly after the initial discovery of superconductivity in iron oxypnictides, Hsu et al. reported that FeSe, crystallizing in the PbO structure type, also displays superconductivity with a transition temperature of 8 K. The layered crystal structure of PbO-type FeSe is characterized by covalently bonded Fe2Se2 layers that are remarkably similar to the Fe2As2 layers present in the quaternary REOFePn (RE = rare earth, Pn = P or As) compounds. Indeed, FeSe can be considered as the parent compound of the iron oxypnictides and pnictides, and also enables the investigation of analogous structure-property relationships in a structurally simpler material system. Studies of FeSe and FeSe1-xTex have confirmed the importance of the iron chemistry in the emergence of superconductivity in layered iron-based materials in general and the importance of controlling the doping.Our group developed the ability to synthesize ferecrystals with a broad range of constituents and a wide range of n and m values over the past several years. This is the first real opportunity for inorganic chemists to prepare large families of structurally related compounds, opening an exciting new area of chemistry to explore.The discovery of iron based superconductivity provided the initiative for us to explore the synthesis of [(FeSe)1+?]m[TSe2]n based ferecrystals. Ferecrystals are a broad new class of materials with turbostratic disorder between crystallographically aligned constituents discovered in our laboratory. We refer to this new state of matter – layered structures with in-plane crystallinity, chemically and structurally abrupt interfamayehces, layer-to-layer misregistration, and turbostratic disorder ¬– as ferecrystals(from Latin fere, meaning almost). We have just begun to explore the preparation of FeSe containing ferecrystals. As shown in the STEM Z-contrast image of [(FeSe)1+?]m[NbSe2]n shown in Figure 1, these materials can be prepared from modulated elemental reactants. This project will involve both preparing[(FeSe)1+?]m[TSe2]n based ferecrystals, varying m, n and the transition metal diselenide, and characterize their electrical properties. We expect that for large values of m and small values of n, we will approach the properties of the parent compound FeSe. By decreasing m, varying the transition metal diselenide, and measuring how properties systematically change we hope to gain insight into the superconducting properties as a function of modulation doping. The student working on this project will learn how to prepare the targeted ferecrystals, determine their structures and any structural distortions within the constituent layers and measure electrical and superconducting properties. The goal is to correlate nanostructure, electrical properties (carrier concentrations, mobility and superconductivity), and structural distortions of the constituents. Our group developed the ability to synthesize ferecrystals with a broad range of constituents and a wide range of n and m values over the past several years. This is the first real opportunity for inorganic chemists to prepare large families of structurally related compounds, opening an exciting new area of chemistry to explore.

Darren W. Johnson
University of Oregon

dwj@uoregon.edu
(541) 346-1695

Website

Title: Synthesis and characterization of inorganic metal clusters (thin film precursors)
Description:
Current methods used to create precursors for the development of thin films transistor and semiconductor devices require either extreme temperature and pressure conditions or organic ligands for high-ordered structures. In the CSMC we are developing techniques to synthesize inorganic metal cluster species as precursors for these applications that have several features: 1) Compact and volatile organic ligands that can be eliminated in the fabrication of materials devices and allow for smooth and defect-free films with high performance characteristics, 2) Variable size and metal composition to affect the stoichiometry and electronic properties of the precursors, and 3) Synthesis at ambient temperature and pressure for low-energy processing. By understanding the current high performing materials in targeted industries (such as semiconductors and solar materials), we try to tailor the composition and stoichiometry of our clusters to directly meet their needs while using low cost, sustainable approaches.Characterization of these materials typically involves identification with single-crystal x-ray diffraction, but recent investigations into the solution state of previously synthesized clusters indicates they remain intact in solution. To date we are using various solution techniques including single angle x-ray scattering (SAXS), nuclear magnetic resonance (NMR) spectroscopy, and infrared (IR) spectroscopy among other techniques to explore the kinetics of cluster formation. Utilization of a combination of these analytical techniques will produce a screening process for cluster development that will decrease synthesis time by eliminating the crystallization process. In the summer a student will have the opportunity to work with a diverse team of grad students, post-docs and faculty in the area of inorganic, solid state and materials chemistry and device engineer learning these characterization techniques as well as help developing and optimizing synthetic procedures for cluster development.

Paul Cheong
Oregon State University

paul.cheong@oregonstate.edu
(541) 737-6760

Website

Title: Using computational tools to discover, explain, and quantify factors that control the stability of mixed metal hydroxo clusters. Project A.
Description: Thin film materials generated from aluminum hydroxo clusters are set to revolutionize the electronics industry. Numerous isomers of these aluminum clusters are known, but only the flat tridecamer isomer is useful for materials applications. It is known that these larger oligomers are formed from monomeric aluminum species, but the mechanism of formation of any of these larger hydroxo metal clusters are still virtually unknown. In this project, the student will learn to apply state-of-the-art theoretical methods to discover, explain, and quantify the detailed atomistic process involved in the formation of these aluminum clusters. Students will learn how to apply and improve these computational tools to obtain the key molecular properties, such as structures, spectra, solubilities, and energies. They will also learn how to properly analyze and interpret the data as well as present the findings in a formal research setting.

Sophia E. Hayes
Washington University

hayes@wustl.edu
(314) 935-4624

Website

Title: Experimentally characterize the structure of inorganic clusters (used as thin-film precursors) by applying both solution-phase and solid-state NMR.
Description: We propose to experimentally characterize the structure of inorganic clusters (used as thin-film precursors) by applying both solution-phase and solid-state NMR. The aim is to provide structure and dynamics information about species such as the [Al13(μ3-OH)6(μ-OH)18 (H2O)24]15+ (“Al13”) and [Ga13(μ3-OH)6(μ-OH)18(H2O)24]15+ (“Ga13”) clusters synthesized by teams at UofO and OSU, and other structural variants. NMR is an inherently element-selective, quantitative, non-destructive form of spectroscopy that provides a unique window into reactions. We intend to examine species in the solid-state—which are particularly important for thin film characterization. We also intend to explore solution-phase NMR to locate sites on the cluster for ligand exchange, degradation, and potentially metal- or oxygen-exchange. Skills that will be used include solid-state NMR and solution-phase NMR of less common nuclei (such as 69/71Ga, 27Al), and abundant 1H species. Students can expect to learn techniques for data analysis and sample handling. We have access to a full array of materials characterization facilities at WashU that a student intern may also be able to utilize (i.e., XRD, TEM, SEM).

Shannon Boettcher
University of Oregon

swb@uoregon.edu
(541) 346-2543

Website

Title: Solution deposition of metal-oxide thin films for solar energy conversion and storage
Description:
Research in the Boettcher lab focuses on materials for solar energy conversion and storage. In particular, we are interested in using solar energy to electrochemically split water into oxygen and hydrogen gas. Your project would be to make and characterize thin films of electrocatalysts for the oxygen evolution half-reaction. We are currently exploring catalyst thin films of earth-abundant transition metal oxides and mixed-metal oxides. We have shown that some of these films, which are made by a solution spin-coating deposition method and are approximately 2 nm thick, show remarkably high activity for oxygen evolution. You research would be to investigate thin films of new materials, including optimization of solution deposition, making electrodes and performing electrochemical measurements, and performing fundamental film characterizations, such as thickness, crystallinity, composition, and morphology. Additionally, for highly active materials, you would be exploring the catalyst activity as a function of several tunable parameters such as film thickness, composition, and micro- and nano-structuring of the films. Undergraduate students in our lab learn about the chemistry of metal oxides, thin film deposition and characterization techniques, and fundamentals of electrochemistry and x-ray crystallography. You will get hands-on experience in our lab with electrochemistry, spin-coating, and film characterization with a quartz-crystal microbalance, as well as hands-on experience with state-of-the-art characterization techniques in the CAMCOR facilities at the UO, including scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Undergraduate students in our lab learn about the chemistry of metal oxides, thin film deposition and characterization techniques, and fundamentals of electrochemistry and x-ray crystallography. You will get hands-on experience in our lab with electrochemistry, spin-coating, and film characterization with a quartz-crystal microbalance, as well as hands-on experience with state-of-the-art characterization techniques in the CAMCOR facilities at the UO, including scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM).

Cathy Page
University of Oregon

cpage@uoregon.edu
(541) 346-4693

Website

Title: Increasing the dielectric constant of solution deposited metal oxide thin films
Description:
Research in the Page lab mainly deals with metal-oxide thin-films deposited from aqueous solutions. We are currently working on dielectric films with the specific aim of increasing the dielectric constant which is related to the polarizability. Typically, the dielectric constants of metal-oxides are relatively low. Incorporation of alkali-metals can increase the dielectric constants far beyond those of simpler systems while retaining many of the desirable properties of the original metal-oxide. Relatively mobile ions within the metal-oxide framework should introduce new variables, so a range of alkali-metals will be investigated. The goal is to correlate film properties to the identity of the alkali-metal introduced into the films. We will develop a simple procedure for producing such alkali-metal metal-oxide films from aqueous solution (in the absence of organics) and characterize them using a variety of instrumentation and device configurations. Research in the Page lab mainly deals with metal-oxide thin-films deposited from aqueous solutions. We are currently working on dielectric films with the specific aim of increasing the dielectric constant which is related to the polarizability. Typically, the dielectric constants of metal-oxides are relatively low. Incorporation of alkali-metals can increase the dielectric constants far beyond those of simpler systems while retaining many of the desirable properties of the original metal-oxide. Relatively mobile ions within the metal-oxide framework should introduce new variables, so a range of alkali-metals will be investigated. The goal is to correlate film properties to the identity of the alkali-metal introduced into the films. We will develop a simple procedure for producing such alkali-metal metal-oxide films from aqueous solution (in the absence of organics) and characterize them using a variety of instrumentation and device configurations.

This project offers a great introduction to some basic solid-state chemistry, exposure to a variety of techniques commonly used to characterize materials and a chance to fabricate and characterize simple electronic devices. The simplicity of film production and device fabrication process will allow plenty of time for data collection and interpretation.

Matt Beekman
University of Oregon

matt.beekman@oit.edu
(541) 885-1940

Title: Structure Function relationships in tin chalcogenide nanolaminates, establishing relationships between the chemistry, structure, and physics of new semiconducting ferecrystal materials synthesized using CSMC thin film deposition techniques
Description:
The unconventional synthesis techniques developed in the CSMC, which allow access to kinetic as opposed to thermodynamic products, have recently resulted in the discovery of a new state of matter that is intermediate between an amorphous and crystalline solid. These nanostructured inorganic intergrowths, referred to as “ferecrystals,” have been synthesized in a wide range of compositions and present unique systems in which nanostructure can precisely controlled by chemical design. This project focuses on understanding the influence of this nanostructure, in particular layer sequence and size, on the electrical and optical properties of tin chalcogenide ferecrystals. This understanding is expected to open new pathways to achieving high performance in electronic, optical, and renewable energy technologies.An undergraduate researcher engaged in this project will contribute to establishing relationships between the chemistry, structure, and physics of new semiconducting ferecrystal materials they synthesize using CSMC thin film deposition techniques. To understand the structural and chemical properties of the materials prepared, the researcher will utilize state of the art techniques available in the Center for Advanced Materials Characterization in Oregon (CAMCOR), including electron microprobe analysis and X-ray diffraction. The researcher will have access to variable temperature measurement systems to analyze the electrical properties such as electrical resistivity and Hall coefficient, with the aim to discover the relationships between the structural, chemical, and electronic properties. The undergraduate researcher will collect, analyze, and interpret their own data under the guidance of their CSMC mentor.

Chris Knutson
University of Oregon

cknutson@uoregon.edu
(541)346-2524

Title: Electrical Properties Study of Amorphous Metal Thin Films
Description:
Recently, amorphous metal thin films have been shown to be useful in tunneling diode switches and anisotropic-dispersion optics. We are interested in increasing the diversity of amorphous metals utilized in these devices, and characterizing the properties of our new systems. Students who choose this project will have the opportunity to assist a graduate student in the study of interdiffusion of ultra-thin metallic layers to form amorphous metal thin films, and perhaps tunneling diode devices. Students will characterize morphology, conductivity, composition and thermal behavior of these films using X-ray diffractometer, electron microprobe analyzer, transmission electron microscope, differential scanning calorimeter and an electrical probe station in order to best match them with suitable applications in nanotechnology.

Greg Herman
Oregon State University

greg.herman@oregonstate.edu
(541) 737-2496

Website

Title: Characterization of Hafnium Oxysulfate, Zirconium Oxysulfate, and Their Nanolaminates
Description: Hafnium oxysulfate (HafSOx) is a promising new material that has a diverse range of practical applications. Capacitors, field effect transistors, and photoresists for use in photolithography can be all be made using HafSOx. High-quality thin films of HafSOx are produced by aqueous based methods. We are interested in determining the role of coordination chemistry on film solubility, ion exchange to produce novel materials, and the role of composition on electrical and chemical properties. Investigations will also be performed to evaluate the potential of HafSOx and zirconium oxysulfate (ZrfSOx) and their nanolaminates as solid superacid catalysts.Detailed surface characterization of these materials is essential in order to better understand their physical and chemical properties and thus facilitate its use in next generation electronic devices and catalytic systems. Temperature programmed desorption, thermogravimetric analysis, secondary ion mass spectroscopy, and x-ray photoelectron spectroscopy will be the main techniques used to characterize thin films and nanolaminates to enhance the current knowledge of these materials.

Bill Casey
University of California, Davis

whcasey@ucdavis.edu
(530) 752-0124

Website

Description: We will start by having the student attempt to make metal-substituted versions of aluminum-hydroxide clusters; these are intended to augment the beautiful aluminum-, indium- and gallium-clusters that Prof. Johnson's lab has pioneered. They will then have to characterize the products using X-ray scattering and electrospray-ionization mass spectroscopy, and voltammetry. The method employed is perfect for an undergraduate as it is not toxic and requires no bizarre expertise. We will attempt to make other types of clusters (e.g., Co(III); Rh(III)).