Andrew Chizmeshya - US grants

This proposal requests funds for the acquisition of a 64-node Linux cluster for bio- and nano-materials simulations. The cluster will be a shared facility to be used by four interdisciplinary research groups in Physics, Materials Science and Engineering, and Chemical Engineering. It will be maintained in partnership with NC State's High Performance Computing group, and used primarily by graduate and postdoctoral students in fullfillment of their research requirements. Current research of the group cuts across computational physics, materials science, and structural biology, with an emphasis on nanotechnology and biophysics applications. Research projects for which the cluster will be used include simulations of biomolecules such as solvated DNA and proteins, dynamics of protein aggregation and molecular recognition phenomena, investigation of quantum transport through molecular electronic systems, studies of nanoindentation, nanofluidics, smart materials, and many more. The research cuts across many length and time scales, and therefore typically requires a multiscale approach. Simulation technology in use ranges from state-of-the art quantum chemistry methods at its most accurate, to finite-element and phase-field approaches at the continuum length scale.


This is an Instrumentation for Materials Research (IMR) proposal aimed at acquiring a computer cluster to be used as a research tool for bio- and nano-materials modeling and student training. The cluster is to be shared by four research groups at NC State, and will maintain and enhance the research competitiveness of the groups. While expecting to use all of the computational cycles that this cluster would bring, any excess cycles will be donated free of charge to the larger NC State research community, thereby ensuring maximum impact and utilization of this important computational resource. The research that will take advantage of this facility will have a broad impact on the development of new materials and simulation technology for bio- and nanotechnology. The latter include topics such as materials with optimized microstructures, probes for the sub-micron scale, mechanical properties of materials relevant for the microelectronics industry, and molecular systems for nanoelectronic applications. Biological research applications include new understanding of protein aggregation, microarrays, the chemical and mechanical properties of DNA and solvated proteins, and understanding of molecular recognition phenomena.

0907600
Menendez

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
Technical. This Focused Research Group (FRG) project explores energy applications of group-IV (Si, Ge) semiconductor materials incorporating Sn. The combination of Sn with Si and Ge may allow desirable structural and electronic properties with advantageous opportunities in photovoltaics and thermoelectricity. Fundamental studies of the Si-Ge-Sn system are planned for the specific purposes: a) designing multijunction solar cells with fully optimized band gaps; b) exploring the potential of the Si-Ge-Sn system for intermediate band photovoltaics; c) designing materials with dramatically enhanced impact ionization rates; d) fabricating structures with ultra-low thermal conductivities; and e) engineering enhanced Seebeck coefficients. The size of the compositional space being explored, combined with possible nanostructural arrangements for a given composition, benefit from a multidisciplinary FRG approach. Theoretical simulations will be used to identify the most promising structures which will be synthesized using CVD methods introducing new precursors and modifications as required. Electrical and contactless optical characterization methods will be employed.
Non-Technical. The project addresses fundamental research issues in a topical area of electronic/photonic materials science having energy related technological relevance. Additionally, the project will include several education/outreach efforts: hosting a regional workshop "Semiconductors and Society" for high school pre-seniors to (i) research student perceptions of how science and engineering innovations impact high-tech products relying on semiconductors (ii) elucidate how intellectual innovations can impact future manufacturing technologies to preserve the semiconductor sector as the major high-technology industry in Arizona and (iii) increase student interest in science and engineering and encourage the pursuit of advanced education in related technical fields. Also, new courses in materials and solid-state chemistry will be developed at ASU with integrated simulation and experimental components. These will be included in the undergraduate curriculum of a newly established "Science Master's in Nanoscience" program. Teaching modules and workshop materials will also be developed and disseminated through the project's web page.

Technical Description: The project investigates the fabrication and properties of (III-V)-IV alloys based on the recent discovery of a synthesis approach that eliminates phase segregation effects in these alloys. The essential idea is to build the alloy crystal from pre-formed molecular units containing three group-IV atoms and a single III-V pair in tetrahedral geometry. Growth is done using chemical vapor deposition on readily available silicon or germanium substrates. The research includes determination of the atomic level structure of the alloys, systematic study of their optical properties, investigation of compositional and doping control for potential semiconductor applications, and generalization of the approach to include most group III, IV, and V materials. An additional goal is to develop other classes of materials based on the concept of molecular building blocks.

Non-technical Description: Modern research in materials science is strongly focused on the design and synthesis of materials not available in nature. The molecular approach to crystal growth exemplified by this project represents a new tool for this quest that may lead to materials with unique properties. In particular, some of the materials to be studied, including alloys of Al, P, N, and Si, are expected to have lattice dimensions similar to a silicon crystal and could form the basis for Si-based tandem solar cells. Single-layer silicon solar cells dominate the current photovoltaics market but their efficiency is limited to about 25%. The cell efficiency could exceed 30% in tandem structures, with large societal impact. The uniqueness of the molecules-to-solids approach also creates opportunities for multidisciplinary education. The project includes the development of new courses that allow students to become familiar with the chemistry and physics concepts needed to pursue materials research. Provisions are also being made to create a database of chemical precursors, to be made available to the community at large, which insures that other researchers have access to the synthetic innovations developed under this project.

This project is funded jointly by the Electronic and Photonic Materials (EPM) and Solid State and Materials Chemistry (SSMC) Programs in the Division of Materials Research.

For more than half a century, scientists have known that the Earth's core - the 3500-km large ball of mostly iron at the center of the planet - has a density 5-10% lower than that of pure iron. This is because the core contains light elements, such as Si, O, S, C, and H. While the core cools down forming the solid inner core, light elements segregate preferentially in the liquid outer core. This process powers in part the magnetic field which shields us from the solar wind. Furthermore, knowing the composition of the core is critical to constrain its formation and evolution. Light elements in metallic iron have, thus, been extensively studied at the extreme pressure and temperature conditions of the deep Earth. However, because of experimental limitations, the effect of hydrogen on core materials is still largely unknown. Here, the researchers investigate how hydrogen affect the properties of the core. Taking advantage of recent technical developments, they study the iron-hydrogen system at the high pressure and temperature of Earth's interior. The experiments, carried out at national synchrotron facilities, quantify the melting temperature and density of iron-rich alloys. Theoretical calculations at the atomic level guide the experimental approach and the data analysis. The results improve current models of the core with implications for the understanding of its formation, evolution and present-day magnetic field, with numerous ramifications in Earth Sciences. This two-year project provides support for an early-career female scientist and a graduate student, and training opportunities for undergraduate summer interns in state-of-the art Mineral Physics. It also increases the public awareness of the important role of hydrogen in the Earth through presentations during open-house events at Arizona State University.

Here, the team investigates Fe-H, Fe-Ni-H and Fe-Si-H alloys in the laser-heated diamond anvil cell (DAC), where specimens are compressed at the tips of two opposing diamonds and heated by focused laser beams. Target pressures and temperatures are up to 150 GPa (~1.5 million atm) and in excess of 2000 K. Quantifying hydrogen-iron alloys at these conditions in the DAC has been challenging because H2 tends to break the anvils on heating. The team has recently demonstrated that this issue can be overcome by pulsed laser heating. This technique, coupled with an improved X-ray detection system at synchrotron facilities, allows the researchers to quantify in situ the effect of hydrogen on the structure, equation of state, bulk modulus and melting temperatures of iron-rich alloys. Run products are investigated by electron microscopy to study their texture and the partitioning of Si and Ni among the phases in presence. Ab initio calculations guide the experimental approach and the data analysis. The key questions leading the research are: (1) Does hydrogen change the crystal structures of iron metal and alloys in the Earth's core? What is the effect of hydrogen on (2) the equations of state of iron metal and alloys and (3) their melting temperatures at core conditions?

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.