Controlled Synthesis, Processing, and Applications of Structural and Functional Nanomaterials: Nanostructured Films & Properties
Sponsored by: ACerS Basic Science Division, ACerS Electronics Division, ACerS Engineering Ceramics Division
Program Organizers: Haitao Zhang, University of North Carolina at Charlotte; Gurpreet Singh, Kansas State University; Kathy Lu, University of Alabama Birmingham; Edward Gorzkowski, Naval Research Laboratory; Jian Shi, Rensselear Polytechnich University; Michael Naguib, Tulane University; Sanjay Mathur, University of Cologne
Tuesday 8:00 AM
October 11, 2022
Room: 320
Location: David L. Lawrence Convention Center
Session Chair: Edward Gorzkowski, Naval Research Laboratory; Haitao Zhang, University of North Carolina at Charlotte
8:00 AM Invited
Ferroelectricity in Hf0.5Zr0.5O2 Films – Processing Options to Achieve Better Ferroelectric Performance: Jacob Jones1; Alex Hsain1; Youghwan Lee1; Gregory Parsons1; 1North Carolina State University
HfO2 has revealed unanticipated dielectric and ferroelectric behavior, creating exciting new opportunities for thin film devices. Enhancing the functional properties of these materials on a variety of substrates, e.g., non-planar and porous, as well as at low processing temperatures opens opportunities for high-efficiency capacitors, integrated devices on flexible and wearable electronics, and novel applications in energy conversion. The vision of our work in HfO2-based ferroelectric films is to enable new functional applications of ferroelectric thin films (10-30 nm) based on doped HfO2 and HfxZr1-xO2 by advancing the underlying processing science, mostly associated with Atomic Layer Deposition (ALD). This presentation will review the dependence of composition (x) in HfxZr1-xO2 (DOI: 10.1063/5.0002835), a new process for depositing TiN electrodes in ALD, a processing process we called Sequential, No-Atmosphere Processing (SNAP) (DOI: 10.1063/5.0029532), and our recent results on the control of texture and it’s effect on ferroelectric properties.
8:30 AM Invited
Quantifying the Electrode Clamping Effect and Its Role on Phase Stability in Ferroelectric Hafnium Zirconium Oxide: Jon Ihlefeld1; Shelby Fields1; Truong Cai2; Samantha Jaszewski1; Kyle Kelley3; Helge Heinrich1; M. Henry4; Brian Sheldon2; 1University of Virginia; 2Brown University; 3Oak Ridge National Laboratory; 4Sandia National Laboratories
Ferroelectric hafnia-based films hold unprecedented promise for advancing the use of ferroelectrics in microelectronics owing to their lack of size effects and compatibility with mainstream semiconductors. Ferroelectric response is attributed to a metastable orthorhombic phase, whose origin is widely debated. The impact of biaxial tensile stress on phase stability will be discussed. It will be shown how the presence of a top electrode during the crystallization anneal imparts a different stress state to the film/substrate stack during heating than that without the top electrode. The differences were quantified at each processing stage and the stress within the hafnia layer was isolated via XRD sin2(Ψ) analyses. It will be shown that the activation barrier for transformation from the metastable ferroelectric phase to the equilibrium monoclinic phase is 12 meV/f.u., on the basis of elastic energy analysis. The results provide a path toward preparing phase-pure ferroelectric hafnia films needed for reliable performance.
9:00 AM
Structural and Magnetic Properties of Fe-Ga-Zr Nanocrystalline Alloys: Mohammad Tauhidul Islam1; Ria Nandwana1; Jonathan Healy1; Jenna Jaklich1; Bowen Dong1; Matthew Willard1; Alexander Yu2; Yumi Ijiri2; Emily Moore3; Scott McCall3; 1Case Western Reserve University; 2Oberlin College; 3Lawrence Livermore National Laboratory
Galfenol alloy (Fe1-xGax, x=0.1-0.3) has been widely studied in single crystal form because of its considerable magnetostriction, which is desirable in various sensor applications. However, single crystals are expensive and time consuming to prepare and their substantial coercivity (293 A/m for Fe83Ga17) requires significant magnetic fields to access the full magnetostriction in sensor applications. For these reasons, nanocrystalline Fe-Ga alloys have been considered to enhance magnetic softness and reduce manufacturing cost. We investigated eleven (Fe1-xGax)92Zr8 alloys with varying Ga concentration (x) between 0.15-0.36, which were prepared by rapid solidification. Subsequent annealing resulted in nanocrystalline BCC grains. The saturation magnetization value decreases from 124 Am2/kg to 51 Am2/kg as the Ga content increase from x=0.15 to x=0.36. The alloy with x=0.26 annealed at 550°C for 1 hour shows a peak magnetostriction of 10 ppm with saturation magnetization of 108 Am2/kg and coercivity of 260 A/m. (Supported by LLNL under Contract DE-AC52-07NA2)
9:20 AM
Optimizing Magnetostriction Coefficients in (FeGa)B Nanocrystalline Alloys: Jenna Jaklich1; Mohammad Tauhidul Islam1; Matthew Willard1; Bowen Dong1; Alexander Yu2; Yumi Ijiri2; Emily Moore3; Scott McCall3; 1Case Western Reserve University; 2Oberlin College; 3Lawrence Livermore National Laboratory
Galfenol, an (Fe,Ga)-based alloy, is interesting for sensor technologies because of its sizable magnetostriction coefficient; however, in order to be effective in these applications, the material’s magnetic softness must be improved. To reduce the coercivity, we have prepared a series of nanocrystalline galfenol-like alloys and examined their magnetic and structural properties. We report studies on a series of four synthesized (Fe80Ga20)100-xBx samples with x=8-17 prepared by rapid solidification and subsequent isothermal annealing. Samples were annealed at temperatures between 425°C and 550°C for up to four hours to examine the effects heat treatment has on the crystallinity of the samples. The sample with x=17 annealed at 450°C for 30 minutes was found to have the largest magnetostriction 31 ppm, a median magnetization 138.7 (Am2/kg), but the smallest coercivity 2271 (A/m). Several crystalline phases but primarily the Fe3Ga (L12) phase were identified by XRD. (Supported by LLNL under Contract DE-AC52-07NA2)
9:40 AM Invited
Eliminating Artifactural Indentation Size Effects in Nanoindentation of Hard Ceramics: James Wollmershauser1; Boris Feigelson1; John Drazin2; Edward Gorzkowski1; Heonjune Ryou1; 1U.S. Naval Research Laboratory; 2UES, Inc.
Hardness is a ubiquitous characterization tool to measure the worth of ceramics and with the advent of instrumented indentation, use has only increased. However, instrumented indentation, primarily nanoindentation, measures hardness differently than classical methods such as Vickers or Knoop hardness and instrumented indentation habitually provides an inflated hardness value. These inflated hardness values often inversely correlate with indentation depth and the effect is most commonly referred to as indentation size effect (ISE). Oliver & Pharr’s 2004 work refines instrumented indentation calibration and analysis methods, and we show that ISE can be eliminated in fully dense hard ceramics when utilizing their approach. Using magnesium aluminate spinel ceramic samples with grain sizes ranging from ~20 nanometers to ~20 micrometers, we prove that ISE is negligent for contact depths from 20 nanometers to 1 micron. Such an implementation and analysis is critical when determining hardness values for new materials, including superhard and nanomaterials.
10:10 AM Break
10:30 AM Invited
Nanomechanical Behavior of Nanocrystalline Spinel at Elevated Temperature: Corinne Packard1; 1Colorado School of Mines
Nanocrystalline magnesium aluminate spinel (MgAl2O4) exhibits exceptional hardness in excess of 20 GPa for grain sizes below 50 nm. Using spinel samples with grain sizes ranging over 4-100 nm formed by EC-PAS (environmentally controlled pressure-assisted sintering) at the US Naval Research Laboratory, we studied the thermal stability and mechanical properties from room temperature to 400C for samples using x-ray diffraction and nanoindentation, respectively. Annealing of spinel samples at 400C, a significant fraction of the sintering temperature (640-850C), for 24 hours resulted in no grain size evolution. Elevated temperature nanoindentation testing resulted in a minor, but transient reduction in hardness that was recovered upon return to room temperature. Variations in the degree of flow serration were also observed. Additionally, we measured statistically significant transient and permanent changes to the elastic moduli of the samples, potentially indicating an internal relaxation of the structure unrelated to grain size.
11:00 AM
Reduced Pressure Nanosintering during Environmentally-Controlled Pressure-Assisted Sintering: Kevin Anderson1; James Wollmershauser1; Boris Feigelson1; 1U.S. Naval Research Laboratory
Nanocrystalline ceramics exhibit a diverse set of exceptional properties but despite rapid innovation in the processing of these materials, bulk production at an industrial scale remains a challenge. A recent but proven process, Environmentally Controlled – Pressure Assisted Sintering (EC-PAS) has been utilized to fabricate a broad range of fully dense nanocrystalline materials, including MgAl2O4 spinel with grain sizes below 4 nm. EC-PAS enables densification with negligible grain growth through a combination of applied pressure (< 2 GPa), low temperature (< 0.5 Tm), and the creation and preservation of pristine nanoparticle surfaces throughout the sintering process. In this work, the scalability of EC-PAS was demonstrated through innovative tuning of heating schedules to compensate for reduced applied pressures. Using MgAl2O4 as a model system, an iterative approach was applied to enable nanosintering at industrially relevant pressures. Optimum sintering parameters will be discussed, in addition to the future prospects of this approach.
11:20 AM
Plateau-Rayleigh Instability with a Grain Boundary Twist: Omar Hussein1; Keith Coffman2; Khalid Hattar3; Eric Lang3; Shen Dillon4; Fadi Abdeljawad1; 1Clemson University; 2University of Illinois Urbana-Champaign; 3Sandia National Laboratories; 4University of California Irvine
Recent advances in high-precision manufacturing techniques have enabled the fabrication of materials architectures with intricate nanoscale features. However, the microstructural stability of nanoscale rod morphologies remains poorly understood. Our recent experiments demonstrate a morphological instability in which a polycrystalline micro- or nanoscale rod breaks up into single-crystal domains, a phenomenon reminiscent of the Plateau-Rayleigh instability. Here, we develop a theoretical model to investigate the impact of grain boundaries (GBs) on the morphological instabilities of polycrystalline nanoscale rods. A neutral stability surface is obtained, which demarcates stable and unstable perturbations with respect to the breakup. We complement our thermodynamic treatment with phase-field simulation studies that capture the kinetics of morphological instability. The theoretical and phase-field modeling studies are in agreement with our experimental studies on a model Alumina system. In broad terms, our present work provides a framework to study the microstructural stability of nanoscale ligament geometries.
11:40 AM
Effect of Strain on the Thermoelectric Properties of Epitaxial La0.8Sr0.2CoO3 Thin Films: Mohammad El Loubani1; Gene Yang1; David Hill1; Dongkyu Lee1; 1University of South Carolina
ABO3 oxides have been highlighted as an alternative material for thermoelectric (TE) generators, which convert heat energy into electricity. The TE efficiency is mainly dependent on the intrinsic properties such as the thermopower and electrical conductivity of oxides, where oxygen defects play a determining role in such properties. In this regard, using epitaxial strain induced by the lattice mismatch between the film and the substrate is a promising approach to modulate the concentration of oxygen defects controlling the TE efficiency. However, the influence of strain on the thermoelectric properties of oxide materials is not fully understood. In this study, using epitaxial La0.8Sr0.2CoO3 thin films as a model system, we investigate the effect of strain-controlled oxygen defects on thermoelectric properties of oxides. Films with zero-, tensile-, compressive strain are evaluated in terms of oxygen vacancies, thermopower, and electrical conductivity. We show that strain can effectively control the TE efficiency.
12:00 PM
Fundamental Understanding of Defect Evolution in Two-dimensional Phosphorus Under Ion Irradiation: Saransh Gupta1; Badri Narayanan1; 1University of Louisville
Controlled introduction of defects in phosphorene using high-energy ion beams offers a promising route to design novel high performance materials for energy technologies. However, this promise remains far from being fully realized due to lack of fundamental understanding of the atomic-scale mechanisms underlying production, accumulation, and temporal evolution of defects during ion irradiation. Here, we employ combination of classical and ab initio molecular dynamics simulations to elucidate the effect of (a) energy, angle of incidence, and mass of noble gas ions on formation of various types of point/topological defects, (b) ion-fluence on structural damage, dynamical evolution of defects, and their relaxation mechanisms during subsequent annealing; as well as (c) reactivity of incoming ion-beams (e.g., halogens) on structural evolution. These findings provide new perspectives to use ion beams to precisely control the concentration and distribution of specific defect types in phosphorene for emerging applications in electronics, batteries, sensing, and neuromorphic computing.