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Full-Text Articles in Engineering
Effect Of Surface Roughness On Ultrasonic Inspection Of Electron Beam Melting Ti‐6al‐4v, Evan T. Hanks, Anthony N. Palazotto, David Liu
Effect Of Surface Roughness On Ultrasonic Inspection Of Electron Beam Melting Ti‐6al‐4v, Evan T. Hanks, Anthony N. Palazotto, David Liu
Faculty Publications
Experimental research was conducted on the effects of surface roughness on ultrasonic non-destructive testing of electron beam melted (EBM) additively manufactured Ti-6Al-4V. Additive manufacturing (AM) is a developing technology with many potential benefits, but certain challenges posed by its use require further research before AM parts are viable for widespread use in the aviation industry. Possible applications of this new technology include aircraft battle damage repair (ABDR), small batch manufacturing to fill supply gaps and replacement for obsolete parts. This paper aims to assess the effectiveness of ultrasonic inspection in detecting manufactured flaws in EBM-manufactured Ti-6Al-4V. Additively manufactured EBM products …
Deep Donors And Acceptors In Β-Ga2O3 Crystals: Determination Of The Fe2+/3+ Level By A Noncontact Method, Christopher A. Lenyk, Trevor A . Gustafson, Larry E. Halliburton, Nancy C. Giles
Deep Donors And Acceptors In Β-Ga2O3 Crystals: Determination Of The Fe2+/3+ Level By A Noncontact Method, Christopher A. Lenyk, Trevor A . Gustafson, Larry E. Halliburton, Nancy C. Giles
Faculty Publications
Electron paramagnetic resonance (EPR), infrared absorption, and thermoluminescence (TL) are used to determine the Fe2+/3+ level in Fe-doped β-Ga2O3 crystals. With these noncontact spectroscopy methods, a value of 0.84 ± 0.05 eV below the conduction band is obtained for this level. Our results clearly establish that the E2 level observed in deep level transient spectroscopy (DLTS) experiments is due to the thermal release of electrons from Fe2+ ions. The crystals used in this investigation were grown by the Czochralski method and contained large concentrations of Fe acceptors and Ir donors, and trace amounts of Cr …
Nonlinearities And Carrier Dynamics In Refractory Plasmonic Tin Thin Films, Heather George, Jennifer Reed, Manuel R. Ferdinandus, Clayton Devault, Alexei Lagutchev, Augustine Urbas, Theodore B. Norris, Vladimir M. Shalaev, Alexandra Boltasseva, Nathaniel Kinsey
Nonlinearities And Carrier Dynamics In Refractory Plasmonic Tin Thin Films, Heather George, Jennifer Reed, Manuel R. Ferdinandus, Clayton Devault, Alexei Lagutchev, Augustine Urbas, Theodore B. Norris, Vladimir M. Shalaev, Alexandra Boltasseva, Nathaniel Kinsey
Faculty Publications
Titanium nitride is widely used in plasmonic applications, due to its robustness and optical properties which resemble those of gold. Despite this interest, the nonlinear properties have only recently begun to be investigated. In this work, beam deflection and non-degenerate femtosecond pump-probe spectroscopy (800 nm pump and 650 nm probe) were used to measure the real and imaginary transient nonlinear response of 30-nm-thick TiN films on sapphire and fused silica in the metallic region governed by Fermi-smearing nonlinearities. In contrast to other metals, it is found that TiN exhibits non-instantaneous positive refraction and reverse saturable absorption whose relaxation is dominated …
Optical Response Of Bifeo3 Films Subjected To Uniaxial Strain, Andrew Herklotz, Stefania Rus, Changhee Sohn, Santosh Kc, Valentino Cooper, Er-Jia Guo, Thomas Ward
Optical Response Of Bifeo3 Films Subjected To Uniaxial Strain, Andrew Herklotz, Stefania Rus, Changhee Sohn, Santosh Kc, Valentino Cooper, Er-Jia Guo, Thomas Ward
Faculty Publications
The impact of single-axis lattice expansion on the optical response of BiFeO3 films is examined. Low-energy He implantation is used to tailor morphotropic phases of BiFeO3 films and study changes in their optical spectra with continuously increasing lattice expansion. He ion implantation of epitaxial rhombohedral (R)- and tetragonal (T)-like BiFeO3 films induces uniaxial out-of-plane strain that, on R-like films, eventually leads to a complete R-T phase transition. This approach allows us to provide insights into the optical response of BiFeO3 films. Strain doping of T-like films leads to a significant redshift of the optical absorption spectra that is theoretically explained …
Non-Conventional Mechanism Of Ferroelectric Fatigue Via Cation Migration, Anton Ievlev, Santosh Kc, Rama Vasudevan, Yunseok Kim, Xiaoli Lu, Marin Alexe, Valentino Cooper, Sergei Kalinin, Olga Ovchinnikova
Non-Conventional Mechanism Of Ferroelectric Fatigue Via Cation Migration, Anton Ievlev, Santosh Kc, Rama Vasudevan, Yunseok Kim, Xiaoli Lu, Marin Alexe, Valentino Cooper, Sergei Kalinin, Olga Ovchinnikova
Faculty Publications
The unique properties of ferroelectric materials enable a plethora of applications, which are hindered by the phenomenon known as ferroelectric fatigue that leads to the degradation of ferroelectric properties with polarization cycling. Multiple microscopic models explaining fatigue have been suggested; however, the chemical origins remain poorly understood. Here, we utilize multimodal chemical imaging that combines atomic force microscopy with time-of-flight secondary mass spectrometry to explore the chemical phenomena associated with fatigue in PbZr0.2Ti0.8O3 (PZT) thin films. Investigations reveal that the degradation of ferroelectric properties is correlated with a local chemical change and migration of electrode ions into the PZT structure. …
Tuned Photomechanical Switching Of Laterally Constrained Arches, Matthew L. Smith, J Gao, A A. Skandani, N Deering, D H. Wang, A A. Sicard, M Plaver, L-S Tan, T J. White, M R. Shankar
Tuned Photomechanical Switching Of Laterally Constrained Arches, Matthew L. Smith, J Gao, A A. Skandani, N Deering, D H. Wang, A A. Sicard, M Plaver, L-S Tan, T J. White, M R. Shankar
Faculty Publications
Laterally constrained arches driven between stable states by light, represent a unique space for compliant mechanism design. Exploiting mechanical multistability can overcome limitations of functional photomechanical actuators, which include limited repeatability, actuation speed, and positioning characteristics. Here, the addition of lateral constraints to an elastic bistable arch system is proposed as a method for toggling between bifurcated states by controlling the location of actinic irradiation. This approach expands the design space for photomechanical, mutistable structures and actuators. Arch behavior as a function of system parameters is simulated, including conditions leading to multistability. An experimental demonstration and exploration of a constrained …