Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 29 for “"time-domain thermoreflectance"”.
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Detecting coherent phonon wave effects in superlattices using time-domain thermoreflectance
… of the SLs are measured using a transient thermoreflectance (TTR) technique at temperatures ranging from 30K to 300K. The results are the first-ever experimental evidence for the presence of coherent wave effects in heat transport through SLs.
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Nature and Dynamics of Earth and Planetary Cores From High-Pressure Properties of Iron -Rich Alloys
… of compressed materials, I employed the time-domain thermoreflectance (TDTR) method combining with the diamond anvil cell technique (Chapter 5). I report high-pressure thermal conductivity data of water and ice phases up to 11 GPa and at 300 K. The thermal conductivity of Ice VII …
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Thermal conductivity anisotropy in molybdenum disulfide thin films
… Thermal conductivities were measured using the time-domain thermoreflectance method. MoS2 samples were prepared with different crystallographic orientations relative to the substrate by magnetron sputtering and ion-beam-assisted deposition. The thermal conductivity of MoS2 was measured as low as …
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Experiments on the Thermal, Electrical, and Plasmonic Properties of Nanostructured Materials
… thin films, an alternative frequency-domain thermoreflectance method for thin film thermal conductivity measurement, thermal rectification in nanodendritic porous silicon, and plasmonic enhancement in silver nanospheroids as a reverse photolithography technique. Nanostructured …
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Near junction thermal management of GaN HEMTs via wafer bonding
… interface thermal conductivity is measured via time domain thermoreflectance. The results of these measurements are analyzed to determine the thermal performance of the structure. In all, this thesis shows that the proposed bonded technology is a promising method for the fabrication of the next …
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A Nanoengineering Approach to Oxide Thermoelectrics For Energy Harvesting Applications
… were measured at room temperature using Time Domain Thermoreflectance.
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MEMS Technologies for Energy Harvesting and Sensing
… utilized in Piezo-MEMS devices: (1) Temperature-Time Transformation (TTT) diagrams are used to document texture evolution during thermal treatment of ceramics. Multinomial and multivariate regression techniques were utilized to create the predictor models for TTT data of Pb(Zr0.60Ti0.40 O3) …
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Expanding ultrafast photoacoustics for investigation of mechanical properties and thermal transport
… reflectance, polarization, and diffraction over time. A magnetostrictive material galfenol (Fe₁₋[subscript x] Ga[subscript x]) with 80 percent iron and 20 percent gallium was used as an acoustic transducer using demagnetostriction effect. Galfenol showed great potential as an optimal transducer …
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Mapping the thermal conductivity of SiC/SiC composites
This thesis investigates the uses of time-domain thermoreflectance (TDTR) to map the thermal conductivity of SiC/SiC composites that are being considered for use as replacement materials in current light-water reactors (LWR), and also as materials for use in next generation nuclear reactors. The …
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Thermal Transport on the Nanometer Scale and the Effect of Microstructure and Interface Resistance
… at temperatures between 79.4 and 294 K using time-domain thermoreflectance, are essentially identical and in good agreement with the predictions of lattice dynamics models and the diffuse mismatch model. Near room temperature G ≈ 700 MW m-2 K-1, ≈5 times larger than the highest values …
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Testing theories for thermal transport using high pressure
… using an ultrafast pump-probe method, time-domain thermoreflectance (TDTR), combined with gem anvil cell techniques. I demonstrated that pressure tuning of physical properties of materials is an elegant approach to test the validity of theories for thermal transport. Pressure dependence …
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Variational approach to solving the phonon Boltzmann transport equation for analyzing nanoscale thermal transport experiments
Over time, technology has shrunk to smaller length scales, and as a result the heat transport in these systems has entered the nanoscale regime. With increasing computational speed and power consumption, there is a need to efficiently dissipate the heat generated for proper thermal management of …
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Thermal conductivity of UO2 and U3O8 epitaxial layers damaged by ion irradiation
… measured by an optical pump-probe technique – time-domain thermoreflectance (TDTR) – and a heat transport model the thermal conductivity of the sample under study can be determined. For UO2, the thermal conductivity is found to be 10.2 W/m.K at 323 K and with increasing temperatures its …
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Exploring heat transfer at the atomistic level for thermal energy conversion and management
… interface thermal conductance using ultrafast time-domain thermoreflectance experiments, examining thermal transport across solid-liquid interfaces modified by self-assembled monolayers. We find that an extra molecular layer can enhance the thermal transport across solid-liquid interfaces. In …
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Observation and manipulation of the wave nature of phonon thermal transport through superlattices
… SLs using two different optical techniques, time-domain thermoreflectance (TDTR) for cross-plane measurements, and transient thermal grating (TTG) for in-plane measurements. The results of this study lend insight into the role of interface scattering, previously understood to be the dominant …
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Nanoscale thermal transport through solid-solid and solid-liquid interfaces
… non-contact optical measurement technique called Time-Domain Thermoreflectance (TDTR) that relies on the fact that the reflectivity of a metal has a small, but measurable, dependence on temperature. The first half of this dissertation is focused on investigating heat transport through thin films …
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Magnon and phonon thermal transport in oxides
… studies, I use ultrafast pump-probe metrology, time-domain thermoreflectance to measure the thermal conductivity. The first subject is the relationship between magnons and phonons in low-dimensional quantum magnets, cuprates, which have high magnon thermal conductivity even at room temperature. …
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Thermal conductivity switching of polymers and lithium-ion battery electrode materials in response to external stimuli
… of LCNs and azopolymers were studied by in-situ time-domain thermoreflectance (TDTR) and in-situ synchrotron X-ray scattering techniques under external stimuli. I observed thermal conductivity switching contrast r = Λhigh/Λlow ~ 1.5–3.5 on a switching time of τ ~ 10 s – 10 min for LCNs and …
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Studying phonon mean free paths at the nanoscale : modeling and experiments
… wire grid linear polarizer in conjunction with time-domain thermoreflectance (TDTR) pump-and-probe measurement setup. Consistent algorithm based on solution from the phonon Boltzmann transport equation (BTE) is also developed to approximately extract the thermal conductivity accumulation …
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Heat Transport across Dissimilar Materials
… transport mechanisms across such interfaces. A time-domain thermoreflectance (TDTR) system is used to measure the thermal properties at the nanoscale. TDTR is an optical pump-probe technique, and it is capable of measuring thermal conductivity, k, and interface thermal conductance, G, …
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