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Award Detail

Doing Business As Name:Oregon State University
  • Melissa K Santala
  • (541) 737-8272
Award Date:01/10/2020
Estimated Total Award Amount: $ 755,612
Funds Obligated to Date: $ 445,442
  • FY 2020=$445,442
Start Date:05/01/2020
End Date:04/30/2025
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.049
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:CAREER: Revealing the Crystallization Kinetics of Marginal Glass Formers Through In Situ Microscopy and Nanocalorimetry Experiments
Federal Award ID Number:1945520
DUNS ID:053599908
Parent DUNS ID:053599908
Program Officer:
  • Lynnette Madsen
  • (703) 292-4936

Awardee Location

Awardee Cong. District:04

Primary Place of Performance

Organization Name:Oregon State University
Cong. District:04

Abstract at Time of Award

NON-TECHNICAL DESCRIPTION: Phase change materials (PCMs) are materials, generally consisting of antimony and tellurium alloyed with other elements, that are used in memory devices. Data is stored in amorphous (glassy) and crystalline bits of PCMs, which may be considered “bad” glasses because they can crystallize extremely rapidly. Rapid crystallization is required for PCM-based memory, but it makes it difficult to acquire experimental data on the physical mechanisms of crystallization and on the heat flow during the process. These data are needed to test the models that form the basis of understanding of PCM behavior that enables the development of new technologically-useful materials. This project addresses the gap in experimental data by utilizing recent advances in microscopy and nanocalorimetry. Calorimetry is used to measure the heat absorbed or released during a reaction, and now advanced microscopic methods can be used to directly observe crystal growth while simultaneous nanocalorimetry yields data on heat flow during crystallization. The results are of value to scientific communities researching materials for low-power, non-volatile memory. Graduate and undergraduate students engaged in this research are being prepared for careers in characterization and development of advanced materials in research laboratories or high-tech industries. The project supports participation of high school students from traditionally-underrepresented groups in science and engineering in a summer educational program. It also supports the establishment of An Expanding Your Horizons conference for middle school girls, the first of its kind in Oregon. TECHNICAL DETAILS: Crystallization kinetics are key to understanding glass stability across all classes of materials. The data needed to extract important relationships between viscosity, crystal growth rate, and temperature are incomplete for important materials that are marginal glass formers, such as phase change materials (PCMs). PCMs are (semiconducting) alloys used in optical- and resistivity-based memory owing to their fast switching between amorphous and crystalline states. The relationship between crystal growth and viscosity with changes in temperature is not fully understood because crystallization can be so rapid the measurement of physical and thermodynamic properties during crystallization is frustrated. Multiple recent reports of crystal growth and viscosity behavior extracted from calorimetric measurements do not satisfactorily fit existing models of crystal growth. This discrepancy may be due to changes in crystallization mechanism and flawed assumptions about the relative contribution of nucleation and growth in different temperature regimes. In this project, crystallization is being studied with in situ microscopic methods, enabling direct observation of crystal growth and revealing changes in phase transformation mechanisms. Recent advances in transmission electron microscopy (TEM) techniques have made this endeavor possible even at temperatures where crystal growth is extremely rapid. In situ TEM with simultaneous nanocalorimetry provides a seamless connection between thermodynamic and kinetic data. Knowledge resulting from this research advances the understanding of glass stability in PCMs and is of value to scientific communities researching materials for low-power, non-volatile memory and other marginal glass formers, such as bulk metallic glasses. Graduate students participating in this project gain foundational knowledge of the thermodynamics and kinetics of phase transformations and employ cutting-edge in situ TEM and calorimetric characterization techniques. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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