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Title: Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements

We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 111; Journal Issue: 5; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 47 OTHER INSTRUMENTATION
OSTI Identifier:
1400173

Wang, Hsin, Porter, Wallace D., and Dinwiddie, Ralph Barton. Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements. United States: N. p., Web. doi:10.1063/1.4991352.
Wang, Hsin, Porter, Wallace D., & Dinwiddie, Ralph Barton. Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements. United States. doi:10.1063/1.4991352.
Wang, Hsin, Porter, Wallace D., and Dinwiddie, Ralph Barton. 2017. "Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements". United States. doi:10.1063/1.4991352. https://www.osti.gov/servlets/purl/1400173.
@article{osti_1400173,
title = {Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements},
author = {Wang, Hsin and Porter, Wallace D. and Dinwiddie, Ralph Barton},
abstractNote = {We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.},
doi = {10.1063/1.4991352},
journal = {Applied Physics Letters},
number = 5,
volume = 111,
place = {United States},
year = {2017},
month = {8}
}