Phase Transformations in Ceramics: Science and Applications: Prediction and Novel Methods I
Program Organizers: Pankaj Sarin, Oklahoma State University; Waltraud Kriven, University of Illinois at Urbana-Champaign; Sanjay Khare, University of Toledo; Yu Zhong, Worcester Polytechnic Institute

Wednesday 2:00 PM
October 2, 2019
Room: A104
Location: Oregon Convention Center

Session Chair: Pankaj Sarin, Oklahoma State University

2:00 PM  Invited
In-situ X-ray Characterization of Phase Evolution during Solid-state Synthesis of Multicomponent Systems: Sanjit Ghose1; 1Brookhaven National Laboratory
    The discovery of new solid inorganic materials cuts across their synthesis, structure and properties. Understanding the synthesis pathways of these solid-state materials is a prerequisite in correlating the chemistry and structure to properties. Advanced processing and synthesis methods such as High Temperature Flux, Electrical Flash Sintering and Microwave Synthesis, require probing the time resolved state of materials, in order to understand the kinetics and structure of intermediate phases. This need is addressed by fast in-situ atomic level x-ray characterization techniques such as X-ray Diffraction (XRD) and X-ray Pair Distribution Function (PDF) analysis methods. I will be discussing how XRD and PDF tools are used to study the synthesis mechanisms and evolution of crystal compositional phases for the ceramics and battery materials at the XPD beamline at the NSLS-II synchrotron radiation source of Brookhaven National Laboratory. This presentation will open up new ideas to look at new materials with different prospective.

2:30 PM  Invited
Exploring 3-D Reciprocal Space: a Powerful Tool to Answer Basic and Applied Materials Science Questions at 33BM APS: Evguenia Karapetrova1; 1Argonne National Laboratory
     The efficient exploration of large volumes of reciprocal space, made possible by the advent of high frame rate and low noise x-ray area detectors. This allows for rapid characterization of a sample's structure and morphology, as well as all of its crystalline phases, and their orientations can be determined simultaneously. This method is particularly powerful if not all the constituent phases (and the corresponding locations of their diffraction signals) are known, and aids in the discovery of unexpected phenomena or crystal structures. Along with the various sample environments that allow in-situ, to transform the structure and properties of solid, liquid, and gas materials, as well as their interfaces at Advance Photon Source 33 Bending Magnet Beamline. This represents a very powerful and versatile state of the art facility that can achieve answers relatively quickly to very complicated and innovative new materials studies.

3:00 PM  
Unraveling Stress-induced Structure Evolution in Functional Oxides using In-situ Neutron Diffraction: Yan Chen1; Ke An1; 1Oak Ridge National Laboratory
    The stress or pressure provides a weaker thermodynamic driving force in comparison with temperature to alter the structure of ceramics at atomic and meso scales, and the directional stimulation usually triggers complex anisotropic responses in the ceramics. The induced structure evolution often directly links to not only mechanical properties but also functional behaviors, and therefore, it provides important considerations for the functional materials synthesis and their real-world applications where the stresses are realistically encountered. For the mechanism understanding, the highly penetrating time-of-flight neutron diffraction with good temporal and spatial resolution enables the in-situ study of the structural transitions coupled with applied loading. Here, some typical functional oxides are taken as examples to demonstrate the understanding of deformation mechanisms and kinetics of structure evolution under stresses, such as anisotropic straining and ferro-domain switching, displacive phase transformation and charge ordering, revealed by in-situ neutron diffraction.

3:20 PM  Cancelled
Advances in Experimental Techniques for Investigating Microstructure Dependent Phase Transformations: Raman Singh1; Daniel Lowry1; Pankaj Sarin1; 1Oklahoma State University
     Recent advances in full-field experimental techniques have enabled the real-time determination of displacement and strain distributions in complex microstructures at multiple length scales. Two techniques of interest are AFM-based indentation and microscale digital image correlation. These techniques also benefit from the use of full-scale finite element modeling to interpret experimental data in the absence of closed-form analytical solutions.This talk will provide a broad overview of the application of such techniques to various materials problems of interest. Furthermore, the specific application of these two techniques is discussed for characterization of ferroelastic transformation toughening in rare-earth niobates.

3:50 PM Break

4:10 PM  Invited
Single Phase Spinel Produced from Powders of Alumina and Magnesia in Reactive Flash Sintering: Rishi Raj1; 1University of Colorado
    The phenomenon of flash sintering discovered in 2010 is rapidly expanding into the synthesis of ceramics, especially those with complex chemistries. Remarkably in "reactive" flash sintering (RFS) powders of elemental oxides, mixed in stoichiometric proportions react to for single phase spinel, and at the same time, sinter to full density in mere seconds at low furnace temperatures. RFS is emerging as an enabling technology for the synthesis of ceramics of complex chemistries such as spinels, bismuth ferrite and lithium lanthanum zirconate. Please come and listen.

4:40 PM  
Reactive Texturing of Yttria and Ceria TZP in a Strong Magnetic Field: Omer Van Der Biest1; Despoina Vriami1; 1K U Leuven Department Mtm
    Strong texture is achievable in 3Y-TZP by a reactive texturing technique. In suspensions containing monoclinic zirconia the (100) plane can be oriented perpendicular to the magnetic field direction during green forming. When 8Y cubic zirconia is added, a strong texture in the single phase 3Y-TZP is obtained after full reaction between both phases. The (001) plane of the tetragonal phase is perpendicular to the magnetic field with a texture index of 32.5. In contrast, for Ce-TZP a similar strategy meets with less success. The reacting phases are monoclinic zirconia and cubic ceria. The resulting texture of Ce-TZP formed is considerably weaker with a texture index of about 3. For successful reactive texturing of zirconia the differences in composition between the monoclinic and the cubic phases should be small. The texture in the resulting microstructure depends on the details of the phase transformations taking place during the homogenizing sintering treatment.

5:00 PM  
Investigations on the Glass Transition and Crystallisation Behavior of Glasses by Oscillatory Rheometry: Christopher Giehl1; Mario Kleindienst1; Daniela Ehgartner1; 1Anton Paar
    The influence of heating and cooling rates, as well as the time-dependent relaxation behavior, are well-known processes related to the glass transition temperature. However, understanding of the energetic processes occuring near the glass transition and their thermodynamic or kinetic nature are an ongoing matter of debate. We here present quantitative mechanical data on the visco-elasticity of glasses near the glass transition temperature obtained from high temperature oscillatory rheometry. Such measurements provide the relative contributions of viscous and elastic moduli and provide insightful information on the strong or fragile character of glass melts. Frequency-dependent measurements allow to derive relaxation time spectra and the deformation-dependent isothermal glass transition. Furthermore, data from oscillatory measurements are capable to monitor the behaviour of metastable glasses, e.g. for unwanted crystallization or production of glass-ceramics.

5:20 PM  
Direct Conversion of Heat to Electricity using First-order Phase Transformations in Ferroelectrics: Ashley Bucsek1; William Nunn1; Bharat Jalan1; Richard James1; 1University of Minnesota
    The DOE estimates that 68% of all the energy produced in the U.S. is rejected as waste heat, and 60% of unrecovered waste heat is considered ”low grade” because of the difficulty of converting small temperature differences to electric or mechanical energy using existing technologies. Yet, the abundance of natural and industrial waste heat at small temperature differences is a growing and drastically underutilized stockpile of convertible energy. We present a novel energy conversion method that converts small temperature fluctuations directly to electricity using first-order phase transformations in ferroelectric capacitors. We use analogies between the ferroelectric phase transformation and the first-order phase transformation utilized in steam engines to discuss thermodynamic efficiencies and power densities. We also demonstrate the conversion capabilities of such a device using BaTiO3, present a theoretical framework to model the circuit parameters, and discuss using phase engineering to achieve extreme cyclic repeatability.