Cassidy will study the interface of silicon carbide and diamond composites. She will explore different types of grain boundaries and investigate how adding different atoms affect the strength of the composite.
Year: 2019
Trujillo Will Intern This Summer At The Army Research Lab
Dennis will use first-principles and machine learning methods to develop relationships between the electronic properties and strength in silicon carbide-based armor.
Dr. Alpay gave an invited talk at the Army Research Lab
The presentation was titled ‘Design using Atomistic and Mesoscale Models’.
Our research group was awarded a $5.4 million R&D contract by the AFRL
Alpay’s research group, in collaboration with Hebert’s research group and other researchers, will work to provide the next generation manufacturing solutions for the aerospace sector. The project, titled “Simulation-Based Uncertainty Quantification of Manufacturing Technologies,” will help the U.S. Air Force develop more efficient manufacturing processes. The goal is to understand each and every step of the manufacturing process to eliminate failures in specialized aerospace parts. Better understanding the manufacturing process will lead to reduced costs, improved component and system quality, and enhanced industrial capability.
https://today.uconn.edu/2019/03/uconn-receives-major-contract-air-force-rd-advanced-manufacturing/
Dr. Alpay gave an invited talk at Worchester Polytechnic Institute
Publication on Doped Bismuth Ferrite in Scientific Reports
Dr. Alpay gave an invited talk at the Air Force Research Lab
The presentation was titled ‘Accelerating Materials Development using Atomistic and Mesoscale Models’.
Co and Nayak published in Phys. Rev. B
Great work Kevin and Dr. Nayak! They published in Physical Review B, Polarization rotation in Bi4Ti3O12 by isovalent doping at the fluorite sublattice.
Abstract
Bismuth titanate, Bi4Ti3O12 (BiT), is a complex layered ferroelectric material that is composed of three perovskitelike units and one fluoritelike unit stacked alternatively along the transverse direction. The ground-state crystal structure is monoclinic with the spontaneous polarization (∼50μC/cm2) along the plane. BiT typically grows along the c direction in thin-film form, and having the polarization vector aligned with the growth orientation can be beneficial for several potential device applications. It is well known that judicious doping of ferroelectrics is an effective method in adjusting the magnitude and the orientation of the spontaneous polarization. Here, we show using first-principles density-functional theory and a detailed phonon analysis that Bi atoms in the fluoritelike layers have significantly more impact on the magnitude and orientation of the spontaneous polarization vector as compared to the perovskitelike layer. The low-energy hard-phonon modes are characterized by fluoritelike layers experiencing transverse displacements and large changes in Born effective charges on Bi atoms. Thus, the breaking of symmetry caused by doping of Bi sites within the fluoritelike layer leads to the formation of uncancelled permanent dipole moments along the transverse direction. This provides an opportunity for doping the Bi site in the fluoritelike layer. Isovalent dopants P, As, and Sb were studied. P is found to be most effective in the reorientation of the spontaneous polarization. It leads to a threefold enhancement of the out-of-plane component of polarization and to a commensurate rotation of the spontaneous polarization vector by 36.2° towards the transverse direction. DOI: https://doi.org/10.1103/PhysRevB.99.014101