David E. Nikles - US grants

This is an award to the University of Alabama Tuscaloosa for the acquisition of a Rheometrics ARES Rheometer. This instrument will be used by an interdisciplinary group of four investigators and their students in the Materials for Information Technology Center at the University of Alabama for a variety of research projects in the general area of advanced materials development and processing as related to information storage technology. The projects include (1) investigation of the microstructure and microstructure evolution of magnetic dispersions, so as to enable the revolutionary advances necessary for step increases in information storage capacity (2) exploration and characterization of the constitutive behavior of magnetic dispersions, so as to provide the enabling science for development of next generation coating processes, and (3) development of solventless, electron- beam-cured formulations that will eliminate the large release of volatile organic compounds typically associated with magnetic media manufacture. Knowledge of the rheological properties of the materials involved is critical to each of these projects. In addition, the rheometer will be used in an undergraduate chemical engineering course in conjunction with a laboratory demonstration module and a numerical analysis project to educate undergraduate engineers on the importance of non-Newtonian behavior in fluid processing operations.

This is an award to the University of Alabama Tuscaloosa for the acquisition of a Rheometrics ARES rheometer. This instrument will be used by an interdisciplinary group of four investigators and their students in the Materials for Information Technology Center at the University of Alabama for a variety of research projects in the general area of advanced materials development and processing as related to information storage technology. In addition, the rheometer will be used in an undergraduate chemical engineering course in conjunction with a laboratory demonstration module and a numerical analysis project to educate undergraduate engineers on the importance of non-Newtonian behavior in fluid processing operations.

With support from the Chemistry Research Instrumentation and Facilities (CRIF) Program, the Department of Chemistry at the University of Alabama in Tuscaloosa will acquire a nanosecond transient absorption spectrometer. Research will focus on photoinduced electron transfer studies, including a) measurement of electron transfer rates in redox-gradient dendrimers; b) use of fast spectroscopy to understand the phylloquinone cofactor in Photosystem I; and c) investigations of photochemistry in novel chromophores for optical data storage.

Transient absorption spectroscopy is an extremely versatile tool that can be used to probe fundamental photophysical and photochemical processes. These studies will have an impact in a number of areas including materials science and biochemistry.

Non-technical: The atom probe is a microscope that allows three dimensional rendering of individual atoms in a material. By being able to image how atoms cluster together, scientists are able to understand and thereby engineer materials for improved energy conversion, electrical conduction or magnetic data storage. The University of Alabama (UA) has key research programs in these and other areas that require this type of atomic level imaging. UA researchers are working on coatings that can improve the life cycle for turbine blades used in advanced power generators and aircraft engines. Additionally, faculty researchers have sponsored efforts in developing materials for fuel cells. UA houses a government and industrial sponsored magnetic recording research center. This center has active programs in developing materials for high storage densities, high sensitivity sensors and faster logic devices, such as transistors. Most of these materials for these new technologies use oxide-based materials, which are poor electrical conductors. Historically, atom probes required materials that were electrically conductive (metals). Recent advances in laser pulsing has allowed atom probes to image poor electrical conductors, such as semiconductors and insulators. The requested laser attachment to UA's atom probe will subsequently expand the range of materials that can be characterized in these strategic programs. The laser attachment provides a unique capability in fostering collaboration with several regional institutions, including historically black colleges and universities. Additionally, it serves in recruitment of students into the materials science discipline at UA.

Technical: The ability to pin-point an individual atom in a three-dimensional microstructure has become an essential need in materials characterization to link experimental observations to atomic scale modeling. The atom probe instrument field evaporates atoms from a specimen of interest which are collected on a position-sensitive, mass-spectrum detector. By reconstructing the trajectory path and impact position of each ion, a volumetric reconstructed rendering of the material is generated with near atomic precision for each individual atom. Historically, atom probe specimens needed to be conductive in order for the high voltage pulse to propagate to the apex of the specimen to field evaporate the surface atoms. The commercial advent of the laser now allows poor conductors (ceramics and semiconductors) to be thermally assisted in the evaporation process. The University of Alabama (UA) has several research programs that utilize dielectric materials. The ability to characterize these materials by atom probe microscopy would significantly advance these programs. For example, UA's efforts on high-k dielectric HfO2 for next-generation gate-values has shown that nitrogen-doping can significantly reduce intermixing between HfO2 and Si; however, an underlying understanding has been hampered by the inability to characterize subtle composition changes at the interface. UA has a track-record of being leaders in spintronic research for giant magnetoresistance sensors and tunneling magnetoresistance devices. The atom probe's ability to characterize buried oxide interfaces within these thin film stacks would further facilitate our linkage between measured properties and modeling. The laser would also allow us to field evaporate brittle intermetallics, like FePt, that are candidates for ultrahigh magnetic storage media. Finally, UA has active energy-based research programs. The laser attachment to our atom probe would allow us to characterize PtRu alloys on their catalytic support structures, such as graphite and alumina. Similarly, the laser will increase the capability to characterize oxide scale formation in thermal protective coatings used for power generation turbine blades. UA's supporting infrastructure and personnel is exceptionally well equipped to develop atom probe specimens and advance the usage of the laser to a wide range of materials. The increased capability will maintain UA as a national analytical facility and continue to foster our existing outreach research activities with HBCU institutions.

TECHNICAL SUMMARY:

This project will discover methods to synthesize AlMn nanoparticles in the tau phase. Bulk tau-AlMn is ferromagnetic (Ms = 950 emu/cc) with a high magnetocrystalline anisotropy (Ku ~ 1 x 107 erg/cc). These particles are expected to have ideal magnetic properties necessary to support the growth in data storage capacity for magnetic tape beyond the year 2020. This technology demands tight compositional and size distributions. From previous work on FePt it has been determined that a two-step nucleation process can be used to control the compositional uniformity. One metal forms the seed from which the other metal atom heterogeneously nucleates. In this project the approach is to nucleate the formation of Mn seed particles, followed by a heterogeneous reduction of Al3+ at the particle surface. The nucleation step will either be a thermal decomposition of an organometallic manganese compound (e.g., Mn2(CO)10) or reduction of Mn2+. Cyclic voltammetry will be used to determine the reduction potentials for the Mn2+ and Al3+ precursors, thereby providing a means of identifying the reducing agents for the nucleation and growth steps. The particles will be prepared in the presence of trioctylphosphine capping ligands to provide a dispersion of particles in an organic solvent. Reaction conditions will be identified that provide control over the particle composition and size distribution. High resolution TEM images will be used to measure the distributions of particle sizes and EDAX on individual particles will provide their compositions. Post synthesis heat treatment in an inert atmosphere will determine conditions for obtaining the chemically ordered, ferromagnetic tauphase with high magnetocrystalline anisotropy. Time-dependent remnant coercivity measurements will provide values of important magnetic properties, i.e, Ms, Hk, Ku, and V. The effect of particle size, composition and chemical ordering on the magnetic properties will be ascertained.

NON-TECHNICAL SUMMARY:

The world-wide demand for information storage capacity is growing faster than our ability to provide data storage media. Magnetic storage tape is the lowest cost, most reliable and highest volume metric storage density medium for archiving digital data. It is an indispensible component of the overall data storage hierarchy. The Information Storage Industry Consortium (INSIC) has projected that by 2018 current magnetic particles will not support further growth in data storage density. This research project aims at addressing the systematic development of a new class of magnetic nanoparticles that will support further increases in storage density and make tape a viable medium beyond 2018. The particles are a ferromagnetic aluminum-manganese tau phase alloy and this project will discover new chemistry to prepare these particles. The development of these particles will require an essential understanding of compositional, phase and structure stability in multi-component metallic alloys in the nanometer regime. The results will elucidate the intrinsic growth mechanisms of nanoparticles. This will bring to fruition the ability to tailor nanoparticles for applications beyond magnetic storage such as catalysis, hyperthermia cancer treatments, and energy harvesting systems. This project will support a graduate student, who will earn a Ph. D. in Materials Science under the joint direction of D. E. Nikles (chemistry) and G. B. Thompson (metallurgy). The student will have a unique multidisciplinary educational experience at the interface between nanoparticle chemical science and nanoparticle metallurgy. The project will also support a high school student who will spend the summer in doing research as part of a Nanoscience and Engineering High School Internship Program.

The goal of this NUE in Engineering program entitled, "NUE: Societal, Ethical, Economic and Environmental Issues Relevant to Nanotechnology" (a Nano Bio Ethics course), at the University of Alabama (UA) Tuscaloosa, under the direction of Dr. Leila Ladani, is to develop a new multidisciplinary pipeline development co-created course in the University of Alabama's Colleges of Engineering and Arts and Science on nanoscience and its implications with regard to ethics, society, economic considerations and the environment. The course will consist of seven modules consisting of: (1) Introduction to Nanotechnology and Biotechnology, (2) Emerging Applications of Nanotechnology and Biomedicine (3) Seeing is Believing and Micro/Nanofabrication, (4) Economics of Nanotechnology and Biotechnology, (5) Philosophy, Ethics, Science and Engineering, (6) Nanotechnology, Biotechnology and Society, and (7) Nanotechnology, Biotechnology, and the Environment.

The broader impacts of the proposed research address the creation of a pilot pipeline from high schools to major research programs in Alabama. The pipeline will help prepare secondary, two-year and four-year college students for strategic economic sectors in the state tied to emerging technologies while fostering awareness of their implications to society. It is anticipated that the pilot will involve 200 students per year with 40% underrepresented group participation.