Advances and Discoveries in Non-equilibrium Driven Nanomaterials and Thin Films: 2-dimensional Materials and Thin Films
Sponsored by: TMS Functional Materials Division, TMS: Energy Conversion and Storage Committee
Program Organizers: Ritesh Sachan, Oklahoma State University; Srinivasa Rao Singamaneni, University of Texas at El Paso; Amit Pandey, Lockheed Martin Space; Nuggehalli Ravindra, New Jersey Institute of Technology
Monday 2:30 PM
February 24, 2020
Room: Solana
Location: Marriott Marquis Hotel
Session Chair: Amit Pandey, Ansys; Ritesh Sachan, Oklahoma State University
2:30 PM Invited
Tunable 2D Materials from Synthesis to Applications: Wonbong Choi1; 1University of North Texas
Recent advances in atomically thin two-dimensional (2D) materials, specially transition metal dichalcogenides (TMDs), have led to a variety of promising technologies for nanoelectronics, energy storage, and opto-electronics, to name a few. Alloying 2D TMDs is a promising avenue for band gap engineering. The amount of W content (x) in the Mo1-xWxS2 alloy is systemically controlled by the co-sputtering technique. The post-laser process allows layer-by-layer thinning of the Mo1-xWxS2 alloys down to a single-layer; such a layer exhibits tunable properties with the optical band gap ranging from 1.871 to 1.971 eV with the variation in the W content, x = 0 to 1. We also observe stable Li electrodeposition and the suppression of dendrite nucleation sites by 2D MoS2 coating on Li-metal. Our approach can lead to the realization of high energy density and safe Li-metal rechargeable batteries.
3:00 PM Invited
Formation of Reduced Graphene Oxide/amorphous Carbon P-N Junctions via Highly Nonequilibrium Route of Nanosecond Laser Irradiation: Siddharth Gupta1; Jagdish Narayan1; 1North Carolina State University
The device integration of reduced graphene oxide is impeded by scalability and high temperature (>2000 K) required for effective reduction. We present a novel approach for direct laser writing of heavily rGO by nanosecond laser melting of amorphous carbon. Ultrafast quenching from the undercooled melt state results in the conversion of amorphous carbon into large-area rGO. Low undercooling in the melt state, triggers transformation of liquid carbon into graphene. The rGO films exhibit 2600 S cm-1 electrical conductivity and electron mobility as high as 220 cm2/Vs. The ultrafast regrowth of rGO creates an atomically sharp interface between n-type rGO and p-type amorphous carbon, forming p–n junctions with 0.3 V turn-on voltage, 110 @±1.5V rectification ratio and 0.13 eV diode activation energy. This unique method solves the problems of traps and defects associated with equilibrium-based rGO fabrication methods, providing insights into the fundamental mechanism driving laser writing of graphene-based materials.
3:25 PM
Understanding the Effects of Lattice Strain on MoS2 through Irradiation: Kory Burns1; 1University of Florida
The properties of two-dimensional (2D) materials can differ from their bulk counterparts. Throughout their lifetime, 2D materials can be exposed to various harsh environments, which can dramatically alter the structure-property relationships and degrade their physical properties. In this contribution, 2D material of interest is MoS2-the most widely studied transition metal dichalcogenide (TMD) that has wide range of chemical, physical, electrical, and optical properties. This presentation will report experimental high-resolution transmission electron microscopy (HR-TEM) data obtained from MoS2 irradiated to various fluences with 5 MeV Au ions. We investigate the physical processes occurring at multiple length scales in MoS2, determine the structural stability of this 2D material, and correlate the lattice strain to irradiation-induced defects in irradiated MoS2.
3:50 PM
Development of Reactive Molecular Dynamics (MD) and Hybrid Reverse Monte Carlo (HRMC) Modeling to Synthesize Amorphous Boron Carbide: Ridwan Sakidja1; Rajan Khadka1; Nirmal Baishnab1; George Opletal2; 1Missouri State University; 2CSIRO
We performed a systematic computational study on the synthesis process and the resultive structures of amorphous boron carbide (a-BxC) using Reactive Molecular Dynamics(MD) and Hybrid Reverse Monte Carlo technique (HRMC). The Reaxtive MD was used as the means to asess the formation process of the radical species resulted from the ionic bombardments of the ortho-carbone organic precursor and the subequent condensation process. We correlated the effect of partial hydrogenation of the precursor toward the density of the aggregates. For the HRMC study, we used the S(Q), RDF and bond lengths of the sample comparable to the experimental and ab initio models. HRMC adopted the experimental as well as energy-based constraints to help reconstruct more realistic and energetically favorable structures of amorphous solids. A reasonably accurate agreement of structural information between HRMC and Reactive MD generated models was found. The support from DMREF (NSF) Grant No. 1729176 is gratefully acknowledged