Research

Thermal energy storage (TES) materials rapidly absorb and release heat to buffer thermal transients. This improves device or component reliability, and can allow for useful capture and reutilization of low-quality heat, improving overall system efficiencies. Key challenges are demonstrating high energy storage density and high cooling power densities in stable, reversible systems. We have demonstrated a number of important achievements in this area:

• Optimal design of high cooling-power thermal composites.
• Material-specific nucleation catalysts, resulting in significant decrease in subcooling in multiple classes of PCMs.
• Characterize and predict thermophysical properties of novel high energy density phase change material and composites.
• Figure of merit based approaches to afford side-by-side comparison of different materials and optimization of composites.

Applications: Electronics, Aviation/Automotive, Batteries, Oil & Gas, Building/Construction, Home Appliance

Select publications:

1. A. Tamraparni, P.J. Shamberger, J. Felts. Cyclic Stability of Lithium Nitrate Trihydrate in Plate Fin Heat Exchangers, Appl. Therm. Eng. 179, 115476 (2020).  doi: 10.1016/j.applthermaleng.2020.115476
2. A. Hoe*, M. Deckard*, A. Tamraparni, A. Elwany, J. Felts, P.J. Shamberger. Conductive Heat Transfer in Lamellar Phase Change Material Composites, Appl. Therm. Eng. 178, 115553 (2020).  doi: 10.1016/j.applthermaleng.2020.115553
3. Shamberger, P.J., T. Fisher. Cooling Power and Characteristic Times of Composite Heatsinks and Insulants, Int. J. Heat Mass Transfer, 117, 1205-1215 (2018). doi: 10.1016/j.ijheatmasstransfer.2017.10.085
4. Karimineghlani, P., E. Emmons, M. Green, P.J. Shamberger, and S. Sukhishvili. A Temperature-Responsive Polymer Matrix for Controlling Fluidity of an Inorganic Phase Change Material, J. Mater. Chem. A, 5(2), 12474-12482 (2017). doi: 10.1039/C7TA02897K
5. Shamberger, P.J.. Cooling Capacity Figure of Merit for Phase Change Materials, J. of Heat Transfer, 138(2), 024502 1-7 (2016). doi: 10.1115/1.4031252

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Neuromorphic devices may enable higher performance for traditional metrics (e.g., energy consumption per operation), or allow entirely new functionalities (e.g., neuroplasticity) by emulating the function of the brain. Here, we focus on developing materials that exhibit resistance switching (either reversible, or non-volatile) to enable new computational architectures.  Our interests here focus on two areas:

• Identification of switching mechanisms and intrinsic sources of device variability.
• Developing reversible metal-insulator transitions that exhibit desired IV response.

Applications: Neuromorphic Computing, Reconfigurable Electronics, Memory

Select publications:

1. A. Yano*, H. Clarke*, D. Sellers, E.J. Braham, T.E.G. Alivio, S. Banerjee, P.J. Shamberger.  Towards High-Precision Control of Transformation Characteristics in VO2 through Dopant Modulation of Hysteresis, J. Phys. Chem. C., 124(39), 21223-21231 (2020).  doi: 10.1021/acs.jpcc.0c04952.
2. D. Sellers, E. Braham, R. Villarreal, B. Zhang, A. Parija, T.D. Brown*, T. Alivio, H. Clarke*, L. De Jesus, L. Zuin, D. Prendergast, X. Qian, R. Arróyave, P.J. Shamberger, S. Banerjee.  An Atomic Hourglass and Thermometer Based on Diffusion of a Mobile Dopant in VO2, J. Am. Chem. Soc., 142(36), 15513-15526 (2020).  doi: 10.1021/jacs.0c07152
3. H. Clarke*, L. Deremo^#, J. Anderson^#, S. Ganguli, P.J. Shamberger. Conductive Filament Shape in HfO2 Electrochemical Metallization Cells Under a Range of Forming Voltages, Nanotechnology, 55(7), 075706  (2020). doi: 10.1088/1361-6528/ab53a9
4. Clarke, H.*, B. Carraway^#, D. Sellers, E. Braham, S. Banerjee, R. Arróyave, P.J. Shamberger. Nucleation-controlled hysteresis in unstrained hydrothermal VO₂ particles, Phys. Rev. Materials, 2, 103402 (2018). doi: 10.1103/PhysRevMaterials.2.103402
5. Clarke, H.*, T. Brown*, J. Hu, R. Ganguli, A. Reed, A. Voevodin, P.J. Shamberger. Microstructure Dependent Filament Forming Kinetics in HfO2 Programmable Metallization Cells, Nanotechnology, 27(42), 425709 (2016). doi: 10.1088/0957-4484/27/42/425709

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Caloric Effect materials (magnetocaloric, elastocaloric, barocaloric, etc.) rely on changes in an external field which changes the temperature and/or entropy of a system. This phenomenon can potentially form the basis of high-efficiency refrigeration cycles or heat pumps. Despite this promise, a number of transformation kinetics, thermodynamic irreversibilities, and other real aspects of the first order phase transformation detract from the ability of thermodynamic cycles to perform useful work. We have demonstrated a number of advances in this system:

• Developed an approach to analyze arbitrary thermodynamic cycles for different classes of materials on an equivalent basis
• Demonstrated the thermodynamic equivalence of temperature and external magnetic field in hysteresis widths for bulk polycrystalline alloys

Applications: Gas Liquifaction, Home Appliance, Cryogenic Cooling

Select publications:

1. T.D. Brown*, J.-H. Chen, E.J. Braham, S. Stadler, P.J. Shamberger. Dynamic Re-equilibration Controlled Multi-step Transformations in (Mn,Fe)₂(P,Si) Alloys, J. Phys. D: Appl. Phys. 53(20), 205303 (2020). doi: 10.1088/1361-6463/ab768a
2. T.D. Brown*, D. Galvan^#, J. van Buskirk^#, A. Mott, P.J. Shamberger. Effect of Carbide Formation on Phase Equilibria and Compositional Modulation of Transformation Properties in (Mn,Fe)2(P,Si) Alloys, J. Alloys Compounds, 830, 154532 (2020). doi: 10.1016/j.jallcom.2020.154532.
3. Brown, T.D.*, I. Karaman, P.J. Shamberger. Impact of cycle-hysteresis interactions on the performance of giant magnetocaloric effect refrigerants, Materials Research Express, 3, 074001 (2016). doi: 10.1088/2053-1591/3/7/074001 **Emerging Investigators special edition**
4. Brown, T.D.*, N. M. Bruno, J. Chen, I. Karaman, J. Ross, P.J. Shamberger. A Preisach-Based Nonequilibrium Methodology for Simulating Performance of Hysteretic Magnetic Refrigeration Cycles, JOM, 67(9), 2123-2132 (2015).  doi: 10.1007/s11837-015-1519-0

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The role of materials as technology enablers has become increasingly prominent in recent years. In fact, of the fourteen Grand Challenges for Engineering posed by the National Academy of Engineering, at least half require the design and/or development of new materials.

Many studies have suggested that learning can be enhanced when instructors incorporate student-centered, interactive approaches. Moreover, such pedagogical strategies have the potential to
positively affect the further development of the students well beyond their university years.  We have investigated the effectiveness of different engineering pedagogies at both the UG and Graduate level.  We focus on a number of specific areas:

• Use of video lectures to enhance learning outside of class.
• Development of psychometric instruments to measure teaching effectiveness.
• New models of UG and Graduate education.

Dr. Shamberger is a proud senior investigator in the NSF-funded Data-Enabled Discovery and Design of Energy Materials (D³EM) graduate program at Texas A&M, as well as the NSF-funded Multifunctional Materials Research Experience for Undergraduates (REU).

Select Publications:

1. Jung, E.^x, Y. Zhou, R. Arroyave, M. Radovic, P.J. Shamberger. Psychometric Evaluation of the Materials Concept Inventory, in review (2017).
2. Zhou, Y., E. Jung^x, R. Arroyave, M. Radovic, P.J. Shamberger. Incorporating Research Experiences into an Introductory Materials Science Course, Int. J. Eng. Educ., 31(6A), 1491–1503 (2015).