2023 Georgia Tech Symposium & Workshop

This talk presents diffraction-based studies of negative and low thermal expansion (NTE/LTE) materials, emphasizing structural behavior under non-ambient conditions. Using synchrotron and neutron sources, Angus Wilkinson investigates fluoride-based frameworks like ScF₃ and CaZrF₆, which contract upon heating—an uncommon and technologically useful property. The research demonstrates how interstitial fluoride incorporation can tune or eliminate thermal expansion and suppress undesirable low-pressure phase transitions by modifying local structure. While effective in certain systems, this strategy is not universally applicable. The work highlights both the capabilities and limitations of advanced X-ray tools versus modern lab-based setups.

Understanding the microstructural evolution of polycrystalline materials under mechanical and thermal processing is essential for optimizing performance in both metals and crystalline polymers. This presentation explores the interplay between crystallographic texture, strain (both uniform and non-uniform), and residual stress, with an emphasis on their quantification using X-ray diffraction (XRD) and complementary techniques such as electron backscatter diffraction (EBSD). Dr. Garmestani outlines foundational concepts of texture as orientation distribution functions (ODFs), introduces stereographic and pole figure analysis, and discusses mathematical models used to extract meaningful microstructural parameters. Applications range from deformation-induced texturing in metals to layer-by-layer strain accumulation in additive manufacturing. Case studies include thin films, polymeric implants, and 3D printed components, highlighting how tailored texture and minimized residual stress can significantly improve properties such as wear resistance and magnetic response. The talk also underscores the critical role of simulation and verification in predicting microstructural outcomes from process parameters.

This talk explores how diverse X-ray diffraction (XRD) techniques can be strategically applied—individually or in tandem—to guide the discovery and stabilization of metastable materials for energy and electronic applications. The focus is on designing constituent properties such as ferroelectricity, piezoelectricity, and dielectric behavior that are critical to multifunctional materials like multiferroics. Because metastable materials often exhibit properties inaccessible in thermodynamic ground states, their stabilization opens new avenues for functional design. A range of synthetic approaches—epitaxial strain, thermal quenching, heterostructural alloying, particle size effects, and deposition kinetics—are examined with XRD serving as a central diagnostic to monitor phase evolution, domain formation, and polymorphic control. A case study on VO₂ illustrates how amorphous templating and pulsed laser deposition rate significantly influence the stabilization of distinct polymorphs. This work underscores the value of metastability in expanding functional material space and highlights the role of XRD in characterizing complex synthesis pathways.

Poor water solubility limits the development of many small-molecule drugs. Controlling polymorphism—specifically stabilizing metastable, more soluble crystal forms—offers a potential solution. This work explores the use of cellulose nanomaterials (organogels, aerogels, and films) as scaffolds to direct and stabilize pharmaceutical polymorphs. While organogels showed limited control and reproducibility due to scaffold heterogeneity, aerogels provided consistent crystallization of specific polymorphs, such as the orange needle form of ROY. Scaffold properties like pore size, surface chemistry, and material purity were found to strongly influence outcomes. These results demonstrate the promise of nanocellulose aerogels for polymorph stabilization and screening in drug development.

This talk presents two recent advances in operando X-ray diagnostics applied to energy materials, developed in the Chen research group. The first project addresses a long-standing barrier in sodium-ion battery (SIB) cathode design: the irreversible phase transition from P2 to O2 structures that degrades cycling stability. Inspired by lithium-ion systems, the team introduces a novel cathode architecture in which partial substitution of transition metals with lithium stabilizes the P2 phase by suppressing interlayer gliding. Through synthesis guided by in situ high-temperature X-ray diffraction (XRD), the optimized material achieves 94% of its theoretical capacity and exhibits durable cycling with no observable phase transition, confirmed via operando and synchrotron XRD and solid-state NMR. The second project explores phase control in metallic cobalt nanostructures by tuning surface energies through reaction pH. Combining DFT calculations with an in situ hydrothermal synthesis reactor and real-time XRD, the group maps a nanometric phase diagram and demonstrates direct phase selection between FCC and HCP cobalt at the nucleation stage. These case studies highlight how mechanistic insights enabled by operando tools can accelerate rational materials design.

Recent advances in the miniaturization of multilayer ceramic capacitors (MLCCs) have imposed stringent demands on analytical techniques for micro-area residual stress and phase characterization. We present the development and application of a laboratory-based micro-area X-ray diffraction (XRD) system capable of sub-50 μm resolution, optimized for evaluating stress and microstructural features in MLCCs and similar components. Our system integrates a high-flux 1.2 kW microfocus rotating anode source with a confocal multilayer optic to produce a focused beam down to 10 μm, enabling localized analysis of impurity phases and residual stress fields. Using an advanced open-cradle goniometer and 2D hybrid pixel detectors, we demonstrate precise lattice strain and texture measurements with minimal sample damage. The system supports grazing incidence and conventional geometries, providing versatile characterization of thin films and bulk heterostructures. We highlight results from localized stress mapping in BTO-based MLCC cross-sections, including identification of polymorphic impurity phases and evaluation of triaxial stress tensors. This approach offers a robust laboratory alternative to synchrotron-based micro-diffraction, with significant implications for electronic component reliability analysis and materials optimization.

Rare earth elements (REEs) are critical for sustainable technologies but face challenges in supply chain security and environmentally intensive extraction methods. Coal fly ash (CFA), a byproduct of coal combustion, has emerged as a promising alternative REE source due to its high annual production, fine particle size, and significant REE content. This talk presents a multiscale geochemical investigation of REE speciation, distribution, and extractability in CFA. Using synchrotron-based X-ray absorption spectroscopy and microscopy, combined with thermodynamic modeling and selective leaching experiments, we reveal how REE-bearing phases—particularly oxides, phosphates, and encapsulated species within glass matrices—govern recovery potential. Distinct behaviors between Class C and Class F CFA are linked to mineralogical differences, informing optimized extraction strategies. A green, closed-loop recovery method using biodegradable ligands (citrate) and selective precipitation (oxalate) was developed, yielding enriched REE oxalate solids while minimizing secondary waste. Residuals were further converted into zeolite materials for heavy metal immobilization. This approach demonstrates the importance of molecular-scale understanding in designing sustainable resource recovery pathways from complex industrial waste.

The Joint School of Nanoscience and Nanoengineering (JSNN), a collaboration between North Carolina A&T State University and the University of North Carolina at Greensboro, serves as one of the two core sites within SCENIC (Southeastern Nanotechnology Infrastructure Corridor), an NNCI-funded partnership with Georgia Tech’s Institute for Electronics and Nanotechnology (IEN). This presentation provides an overview of JSNN’s capabilities and role in supporting advanced nanoscience research and education across the southeastern U.S. With a strong emphasis on nanoscale characterization, analytical chemistry, and microscopy, JSNN houses a broad array of tools including a newly acquired micro-CT system, advanced Raman and XPS platforms, and a forthcoming Rigaku SmartLab XRD system configured for powder, thin film, and battery materials analysis. The site also supports single-particle analysis, chromatography, spectrometry, and computational modeling. JSNN emphasizes accessibility, offering self-use, collaborative, and fee-for-service modes to academic and industry users alike. The talk highlights the critical function of infrastructure in democratizing access to high-end instrumentation and the strategic coordination between partner institutions to address regional research and workforce development needs.

The convergence of microfocus X-ray sources and advanced detection technologies has expanded the utility of single-crystal diffractometers into the realm of powder diffraction. This presentation outlines strategies for effectively conducting powder X-ray diffraction (XRD) using standard single-crystal instrumentation. With highly collimated and intense microfocused beams, only minimal sample quantities—often less than a milligram—are required. Flexible mounting techniques, such as polymer capillaries and loops, facilitate efficient sample handling, especially for heterogeneous or poorly crystalline materials.

Key methodological considerations are discussed, including detector geometry, sample rotation, multi-offset scan protocols, and long working distances to mitigate peak broadening. The role of modern software, including CrysAlisᴾʳᵒ, MATCH, GSAS, and Endeavour, in streamlining data acquisition, calibration, and structure solution is also emphasized. Case studies ranging from metal oxides to nanomaterials demonstrate the technique’s capacity for rapid phase identification, unit cell refinement, and, in select cases, full structure solution. These results highlight the untapped potential of single-crystal platforms to deliver rich powder diffraction data, particularly in laboratories where sample quantity or beamtime is limited.

This presentation explores two investigative narratives in the field of magnetic materials. The first centers on classic binary manganese chalcogenides, revisiting their magnetic structures using modern techniques such as elastic and inelastic neutron scattering and high-resolution X-ray pair distribution function (PDF) analysis. A notable discovery includes the identification of a previously unobserved third phase of MnSe, stabilized within a narrow temperature window during flash-cooling protocols, with implications for understanding phase transformation kinetics and domain-limited structural coherence.

The second story transitions to new material development, focusing on kagome-like metallic systems within the Y–(Fe,Co)–Ge structure family. By leveraging chemical substitution strategies and electronic structure insights, the Shatruk group successfully tunes magnetic ordering—from antiferromagnetic to ferromagnetic-like states—revealing a phase boundary that holds promise for hosting exotic spin textures. Together, these studies emphasize the power of modern tools in re-examining “known” systems and highlight the continued importance of exploratory synthesis in advancing condensed matter science.

As the silicon era approaches its physical limits, identifying next-generation quantum materials capable of supporting coherent quantum phenomena becomes imperative. In this talk, we present recent efforts to design and synthesize quantum materials that host exotic spin states by chemically tuning their competing exchange interactions. Specifically, we investigate CaMn₂O₆, a spin-3/2 triangular lattice antiferromagnet crystallizing in a noncentrosymmetric space group, as a model system for exploring anisotropic magnetic interactions and geometrical frustration. Structural characterization using synchrotron and neutron diffraction reveals a complex stacking sequence that breaks inversion symmetry—an essential condition for Dzyaloshinskii–Moriya interactions. Magnetic and thermodynamic measurements show subtle antiferromagnetic ordering near 10 K, accompanied by Schottky anomalies and suppressed ordering under applied magnetic fields, suggesting the presence of field-induced spin reconfigurations. Neutron diffraction confirms an incommensurate spiral magnetic ground state, and DFT calculations reveal highly directional Mn–O orbital overlaps, underscoring the role of spin–orbit coupling and structural asymmetry in stabilizing the observed magnetic textures. This work illustrates how chemical design principles can be leveraged to map the interplay of structure and quantum magnetism in the search for materials relevant to quantum information science.