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Title: Pump-probe measurements of the thermal conductivity tensor for materials lacking in-plane symmetry

We previously demonstrated an extension of time-domain thermoreflectance (TDTR) which utilizes offset pump and probe laser locations to measure in-plane thermal transport properties of multilayers. However, the technique was limited to systems of transversely isotropic materials studied using axisymmetric laser intensities. Here, we extend the mathematics so that data reduction can be performed on non-transversely isotropic systems. An analytic solution of the diffusion equation for an N-layer system is given, where each layer has a homogenous but otherwise arbitrary thermal conductivity tensor and the illuminating spots have arbitrary intensity profiles. As a demonstration, we use both TDTR and time-resolved magneto-optic Kerr effect measurements to obtain thermal conductivity tensor elements of <110> α-SiO{sub 2}. We show that the out-of-phase beam offset sweep has full-width half-maxima that contains nearly independent sensitivity to the in-plane thermal conductivity corresponding to the scanning direction. Also, we demonstrate a Nb-V alloy as a low thermal conductivity TDTR transducer layer that helps improve the accuracy of in-plane measurements.
Authors:
 [1] ; ;  [2]
  1. Department of Mechanical Engineering, University of Delaware, Newark, Delaware 19716 (United States)
  2. Department of Materials Science and Engineering, and Frederick-Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)
Publication Date:
OSTI Identifier:
22305908
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ALLOYS; ANALYTICAL SOLUTION; AXIAL SYMMETRY; DIFFUSION EQUATIONS; HEAT TRANSFER; KERR EFFECT; LASERS; PUMPS; REFLECTION; SENSITIVITY; SILICON OXIDES; TENSORS; THERMAL CONDUCTIVITY; TIME RESOLUTION; TRANSDUCERS