Non-contact, non-destructive mapping of thermal diffusivity and surface acoustic wave speed using transient grating spectroscopy

Abstract

We present new developments of the laser-induced transient grating spectroscopy (TGS) technique that enable the measurement of large area 2D maps of thermal diffusivity and surface acoustic wave speed. Additional capabilities include targeted measurements and the ability to accommodate samples with increased surface roughness. These new capabilities are demonstrated by recording large TGS maps of deuterium implanted tungsten, linear friction welded aerospace alloys, and high entropy alloys with a range of grain sizes. The results illustrate the ability to view the grain microstructure in elastically anisotropic samples and to detect anomalies in samples, for example, due to irradiation and previous measurements. They also point to the possibility of using TGS to quantify grain size at the surface of polycrystalline materials.

Perspectives on multiscale modelling and experiments to accelerate materials development for fusion

“…Various advanced experimental characterisation techniques are helping to accelerate model validation by reducing the spatial and temporal gap been simulations/models and experiments, including X-ray diffraction imaging [300,358] and laser-based measurements [316,317,359] .…”

Tutorial: Characterizing Microscale Energy Transport in Materials with Transient Grating Spectroscopy

“…Extensive literature exists about acoustic measurements using TGS to investigate the mechanical properties of various materials [9,31] and evaluate radiation damage in materials [106,107]. Here, we highlight recent applications of TGS to map SAW transport in self-assembled phononic crystals [108].…”

Exceptional Performance of Room Temperature Sputtered Flexible Thermoelectric Thin Film Using High Target Utilisation Sputtering Technique

“…1) Pseudo steady-state 3-𝜔 method [49,50] : the film deposited on the measurement chip may exhibit different properties than that deposited on the polyimide sheet, resulting in a significant difference in 𝜅 (Table S3, Supporting Information). 2) Transient grating spectroscopy: the thermal diffusivity of the "polyimide sample" (as deposited and 350 °C-2 h) was measured using the laser-induced transient grating spectroscopy method [51,52] giving values of 1.2 (±0.06) and 1.4 (±0.07) × 10 −6 m 2 s −1 , respectively (see Figure S11, Supporting Information). Thus the total 𝜅 is calculated to be 1.5 (±0.1) and 1.7 (±0.1) W m −1 K −1 , corresponding to a ZT of 0.13 (±0.01) and 0.40 (±0.05) @300K (showing good agreement with the calculated values of ZT).…”