Research

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. Hence, introductory materials science courses are considered essential components of a typical engineering student’s curriculum, independent of their engineering major.

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).

Magnetocaloric Effect (MCE) materials rely on changes in the external magnetic field to change the temperature and/or entropy of the system. This phenomenon can potentially form the basis of high-efficiency magnetic refrigeration cycles. 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. 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**
2. 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
3. Shamberger, P.J., and F.S. Ohuchi. Hysteresis of the martensitic phase transition in magnetocaloric-effect Ni-Mn-Sn alloys, Phys. Rev. B, 79(14), 144407 (2009).  doi: 10.1103/PhysRevB.79.144407

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The development of the transistor enabled an amazing array of technology and devices which has dramatically impacted all aspects of life in modern societies. While work continues developing smaller, more efficient, faster, and higher power transistors, radical new device configurations are appearing which offer potential for dramatic departure from current device configurations and styles of operation. These new devices may enable higher performance for traditional metrics (e.g., energy consumption per operation), or may allow entirely new functionalities (e.g., neuroplasticity). Here, we focus on one class of materials: non-volatile resistance switches. These generally take a metal-insulator-metal configuration, and operate by one of a number of mechanisms which (either locally or uniformly) changes the conductivity between the two electrodes. Our interests here focus on two areas:

• Identification of switching mechanisms. Different materials systems result from fundamentally different physical processes. The nature of these processes inevitably impacts device behavior.
• Identification of intrinsic materials-focused sources of device variability. Currently, we are focused on the role of grain boundaries in the transport process.

Applications:Neuromorphic Computing, Reconfigurable Electronics, Memory

Select publications:

1. 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
2. Shamberger, P.J.. J.L. Wohlwend, A.J. Roy, A.A. Voevodin. Investigating Grain Boundary Structures and Energetics of Rutile with Reactive Molecular Dynamics, J. Phys. Chem. C, 120(24). 13049-13062 (2016). doi: 10.1021/acs.jpcc.6b02695

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Thermal energy storage (TES) materials are intended to rapidly absorb and release heat to balance thermal transients. This improves device or component reliability, reduces the scale of other thermal components necessary to reject heat at peak heat generation rates, and can allow for useful capture and reutilization of low-quality heat, improving overall system efficiencies. The key challenges in this area 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:

• High cooling-power thermal composites from incompatible materials (graphitic foam, salt hydrate) through use of surfactants.
• Material-specific nucleation catalysts identified through integrated computational database screening approaches.  This approach led to rapid identification of a newly discovered (more stable, more effective) nucleation catalyst for the LiNO3-3H2O system with minimum experimental effort.
• Characterize and predict thermophysical properties of high energy density phase change material
• Derive “cooling power figure of merit” (FOM_q) from analytical solutions to Stefan’s problem. Allows for intelligent materials design and side-by-side comparizon of different materials with different thermophysical properties

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

Select publications:

1. 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
2. Shamberger, P.J., “Nucleating Agent for Lithium Nitrate Trihydrate Thermal Energy Storage Medium.” U.S. Patent 8,703,258, issued April 22, 2014.
3. Shamberger, P.J., M. O’Malley. Heterogeneous Nucleation of Thermal Storage Material LiNO3•3H2O from Stable Lattice-Matched Nucleation Catalysts, Acta Materialia, 84, 265-274 (2015).  doi: 10.1016/j.actamat.2014.10.051
4. Shamberger, P.J., T. Reid. Thermophysical Properties of Potassium Fluoride Tetrahydrate from (243 to 348) K, J. Chem. Eng. Data, 58, 294-300 (2013).  doi: 10.1021/je300854w

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