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Investigating Volumetric Inclusions of Semiconductor Materials to Improve Flashover Resistance in Dielectrics

Steiner, Adam M.; Siefert, Christopher S.; Shipley, Gabriel A.; Redline, Erica M.; Dickens, Sara D.; Jaramillo, Rex J.; Chavez, Tom C.; Hutsel, Brian T.; Frye-Mason, Gregory C.; Peterson, Kyle J.; Bell, Kate S.; Balogun, Shuaib A.; Losego, Mark D.; Sammeth, Torin M.; Kern, Ian J.; Harjes, Cameron D.; Gilmore, Mark A.; Lehr, Jane M.

Abstract not provided.

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TYPE Conference Poster YEAR 2021
OSTIDOI

Phonon scattering mechanisms dictating the thermal conductivity of lead zirconate titanate (PbZr1-xTixO3) thin films across the compositional phase diagram

Journal of Applied Physics

Foley, Brian M.; Paisley, Elizabeth A.; DiAntonio, Christopher D.; Chavez, Tom C.; Blea-Kirby, Mia A.; Brennecka, Geoffrey L.; Gaskins, John T.; Ihlefeld, Jon I.; Hopkins, Patrick E.

This work represents a thorough investigation of the thermal conductivity (κ) in both thin film and bulk PbZr1-xTixO3 (PZT) across the compositional phase diagram. Given the technological importance of PZT as a superb piezoelectric and ferroelectric material in devices and systems impacting a wide array of industries, this research serves to fill the gap in knowledge regarding the thermal properties. The thermal conductivities of both thin film and bulk PZT are found to vary by a considerable margin as a function of composition x. Additionally, we observe a discontinuity in κ in the vicinity of the morphotropic phase boundary (MPB, x = 0.48) where there is a 20%-25% decrease in κ in our thin film data, similar to that found in literature data for bulk PZT. The comparison between bulk and thin film materials highlights the sensitivity of κ to size effects such as film thickness and grain size even in disordered alloy/solid-solution materials. A model for the thermal conductivity of PZT as a function of composition (κ (x)) is presented, which enables the application of the virtual crystal approximation for alloy-type material systems with very different crystals structures, resulting in differing temperature trends for κ. We show that in the case of crystalline solid-solutions where the thermal conductivity of one of the parent materials exhibits glass-like temperature trends the compositional dependence of thermal conductivity is relatively constant for most values of x. This is in stark contrast with the typical trends of thermal conductivity with x in alloys, where the thermal conductivity increases dramatically as the composition of the alloy or solid-solution approaches that of a pure parent materials (i.e., as x = 0 or 1).

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TYPE Journal Article YEAR 2017
ScopusOSTIDOI

Thermal characterization and properties of a copper-diamond composite

DiAntonio, Christopher D.; Chavez, Tom C.; Coker, Eric N.

The thermal properties of a commercial copper-diamond composite were measured from below -50°C to above 200°C. The results of thermal expansion, heat capacity, and thermal diffusivity were reported. These data were used to calculate the thermal conductivity of the composite as a function of temperature in the thickness direction. These results are compared with estimated values based on a simple mixing rule and the temperature dependence of these physical properties is represented by curve fitting equations. These fitting equations can be used for thermal modeling of practical devices/systems at their operation temperatures. The results of the mixing rule showed a consistent correlation between the amount of copper and diamond in the composite, based on density, thermal expansion, and heat capacity measurements. However, there was a disparity between measured and estimated thermal diffusivity and thermal conductivity. These discrepancies can be caused by many intrinsic material issues such as lattice defects and impurities, but the dominant factor is attributed to the large uncertainty of the interfacial thermal conductance between diamond and copper.

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TYPE SAND Report YEAR 2014
OSTIDOI

New composite separator pellet to increase power density and reduce size of thermal batteries

Mondy, L.A.; Evans, Lindsey E.; Roberts, Christine C.; Grillet, Anne M.; Soehnel, Melissa M.; Barringer, David A.; DiAntonio, Christopher D.; Chavez, Tom C.; Ingersoll, David I.; Hughes, Lindsey G.

We show that it is possible to manufacture strong macroporous ceramic films that can be backfilled with electrolyte to form rigid separator pellets suitable for use in thermal batteries. Several new ceramic manufacturing processes are developed to produce sintered magnesium oxide foams with connected porosities of over 80% by volume and with sufficient strength to withstand the battery manufacturing steps. The effects of processing parameters are quantified, and methods to imbibe electrolyte into the ceramic scaffold demonstrated. Preliminary single cell battery testing show that some of our first generation pellets exhibit longer voltage life with comparable resistance at the critical early times to that exhibited by a traditional pressed pellets. Although more development work is needed to optimize the processes to create these rigid separator pellets, the results indicate the potential of such ceramic separator pellets to be equal, if not superior to, current pressed pellets. Furthermore, they could be a replacement for critical material that is no longer available, as well as improving battery separator strength, decreasing production costs, and leading to shorter battery stacks for long-life batteries.

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TYPE SAND Report YEAR 2013
OSTIDOI
Results 1–25 of 81
Results 1–25 of 81