research

Promise in Computational Chemistry Winner

Uchenna Anene won the “Promise in Computational Chemistry” award for speaking at the Women Make COMP symposium of the American Chemical Society, Fall 2021.

Women are under-represented in science and this symposium aimed to address this gender-gap by ensuring that young women in the field had the mentorship to pursue academia and industry fields.

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UConn-Technion Collaboration Develops Model for Affordable Fuel Cell Catalysts

UConn researchers and collaborators at Technion – Israel Institute of Technology developed a theoretical model that will expediate the development of affordable fuel cells, a key technology for sustainable energy.

Radenka Maric, UConn’s vice president for research, innovation and entrepreneurship; Dario Dekel from Technion’s Chemical Engineering Department; S. Pamir Alpay, UConn’s associate dean for research and industrial partnerships; and Sanjubala Sahoo, a research scientist in Alpay’s group published their findings in ACS Catalysis in February.

UConn and Technion Collaborate on the Development of Next Generation Fuel Cells

June 3, 2020

Radenka Maric, UConn’s vice president for research, innovation and entrepreneurship, Dario Dekel from Technion’s Chemical Engineering Department and S. Pamir Alpay, UConn’s associate dean for research and industrial partnerships are working on advanced concepts that will provide novel solutions in catalysis and energy research.

Read the full article here.

Development of New Aluminum Alloys

Our group working with Collins Aerospace developed new aluminum alloys. The research was highlighted by ASM International.

https://www.asminternational.org/home/-/journal_content/56/10180/40278982/NEWS 

Study indicates AlCe and AlCo aluminum binary alloys could be suitable for 3D-printing

April 20, 2020
Source: ASM International

Researchers from the University of Connecticut, Pratt & Whitney, and Collins Aerospace collaborated in an 18-month study in which they used computational tools and a variety of experimental methods to develop simple aluminum binary alloys with properties similar or superior to commercial 6xxx aluminum alloys for additive manufacturing.

The goal was to identify binary systems of the type Al-X that promise hardness advantages after processing under conditions found in a typical metal additive manufacturing environment. DFT and laser surface glazing experiments were used to identify alloy additions to aluminum that induce lattice strains around solute atoms, and that can yield extended solid solubilities.

Given the non-equilibrium nature of rapidly quenched alloys, solid solutions with extended solubilities are metastable in nature and might transform further, for example, into microstructures with clusters or second-phase precipitates. The current work therefore represents an approach to the design of new aluminum alloys specific to non-equilibrium process technologies such as additive manufacturing.

Results show conclusively that cerium and cobalt are promising elements in next-generation aluminum alloys that make use of non-equilibrium processing conditions such as additive manufacturing.

The investigation started with an analysis of solid solution strengthening using first-principles calculations to determine elastic property changes and local lattice distortions from the introduction of different elements into a host aluminum lattice. These results, coupled with both equilibrium and nonequilibrium solubility data, led to the selection of cerium and cobalt as the primary candidate alloying elements. Alloys of Al\\Ce and Al\\Co at concentrations of 0.5, 1.0, and 3.0 at. % were then synthesized and subjected to laser glazing to produce non-equilibrium microstructures.

The microstructure and solid solution characteristics were determined using a combination of scanning electron microscopy and transmission electron microscopy. Hardness was measured by nanoindentation testing, which showed that both candidate systems harden significantly after glazing. In addition, Al-1.0Co at. % achieves a hardness comparable to Al6061-T6.

Following are comments from distinguished materials scientists regarding this study:

Prof. Rainer Hebert, Director – Pratt & Whitney Additive Manufacturing Center, Department of Materials Science and Engineering, University of Connecticut

“This is a comprehensive study where we developed simple Al-binary alloys with similar (if not superior) properties compared to commercial 6xxx series Al alloys. We collaborated extensively with Collins Aerospace and Pratt & Whitney. As such, this is also a great example of industry and academia working side by side in addressing a fundamental problem in metallurgy.”

Prof. Diran Apelian, Distinguished Professor of MSE, Chief Strategy Officer- SSoE, UCI, Irvine, Calif.

“Beauty is usually used as an adjective describing objects, individuals, nature; I will use it here to a manuscript as it exemplifies excellence and a set of standards for us to aspire. A “beautiful” paper in that the hypotheses, the experiments, coupled with a deep dive in ICME calculations, and validation in collaboration with industrial partners, have been executed in a compelling manner. The results are most meaningful and impactful. Accolades to our UConn colleagues.”

Prof. Lesley Frame, Director – Center for Materials Processing Data (CMPD), an ASM International Consortium; Department of Materials Science and Engineering, University
“Successful studies that identify improved methods for materials discovery like this one, illustrate the need for reliable methods of characterizing transient properties of the novel materials. CMPD is taking on the challenge of generating and validating the materials processing data that will support rapid transition from materials discovery to manufacturing application.”

Image: Ball-stick models for supercells constructed from a) 3 × 3 × 3 unit cell and b) 2 × 2 × 2 unit cell, containing 108 atoms and 32 atoms, respectively. The aluminum atoms are represented as smaller yellow balls and the X atom, where X represents elements with atomic number 1–94 (H\\Pu) other than aluminum in the periodic table, is represented by larger blue ball. The ball sizes are not representation of atomic sizes. Substituting one X atom in the supercells leads to concentration of 0.926 at. % and 3.13 at. % for 108 atoms and 32 atoms supercells, respectively.

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Full paper citation:

C. J Hung, S. K. Nayak, Y. Sun, C. Fennessy, V. K. Vedula, S. Tulyani, S.-W. Lee, S. P. Alpay, and R. J. Hebert, “Novel Al-X Alloys with Improved Hardness,” Materials & Design, 192, 108699 (2020); https://doi.org/10.1016/j.matdes.2020.108699

Tulsi & Kevin Publish in the Journal of Applied Physics

Congratulations to Tulsi & Kevin on their publication, “Ferroelectric Films on Metal Substrates: The Role of Thermal Expansion Mismatch on Dielectric, Piezoelectric, and Pyroelectric properties”, in the Journal of Applied Physics for their findings on the role of metallic substrates on the functional properties of PZT solid solutions.

 

Ferroelectric Films on Metal Substrates: The Role of Thermal Expansion Mismatch on Dielectric, Piezoelectric, and Pyroelectric properties
T. A. Patel, K. Co, R. J. Hebert, and S. P. Alpay, J. Appl. Phys. 126, 134103 (2019)
DOI: DOI: https://doi.org/10.1063/1.5116134

ABSTRACT
We present here a comprehensive analysis of the effect of thermal stresses on the functional properties of ferroelectric oxides on metal substrates. We use a Landau-Devonshire formalism to quantitatively assess the role of in-plane thermal strains that arise from the coefficient of thermal expansion (CTE) mismatch between lead zirconate titanate [PbZrxTi1–xO3, PZT x/(1 – x)] films and Al, Cu, Fe, Ni, and Ti-based substrates. Specifically, we compute Curie transition temperatures, spontaneous polarizations, dielectric permittivities, piezoelectric coefficients, and pyroelectric responses of tetragonal PZT compositions as a function of the growth/processing temperature. To provide a rapid evaluation, we also develop Ashby diagrams of property coefficients as a function of PZT composition, processing temperature, and CTE of the substrate. Our results show that thermal strains in PZT may significantly alter the ferroelectric transition temperature, dielectric, piezoelectric, and pyroelectric properties. For example, for PZT 50/50 films on Ni-based superalloys processed/annealed at 700 °C, we predict monodomain intrinsic dielectric, piezoelectric, and pyroelectric responses to be 234, 152 pC/N, and 0.021 μC cm−2 °C−1, respectively, compared to bulk PZT 50/50 values of 381, 326 pC/N, and 0.045 μC cm−2 °C−1. These are substantial variations which show that thermal strains must be considered in the design and development of built-in functionality obtained through ferroelectric films in structural, aerospace components.