Microscale Imaging of Thermal Conductivity Suppression at Grain Boundaries

Isotta, Eleonora; Jiang, Shizhou; Moller, Gregory; Zevalkink, Alexandra; Snyder, G. Jeffrey; Balogun, Oluwaseyi

doi:10.1002/adma.202302777

Cited by 16 publications

(7 citation statements)

References 57 publications

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“…Our ability to achieve this optimization is based on our developed fundamental understanding of how entropy control impacts the thermoelectric properties of PbGeSnAg x Sb x Se 1.5+ x Te 1.5+ x and related systems, gained through our detailed investigation of the intricate interplay between crystal symmetry, polar domains, and transport properties. A potential future study could be implementing local measurement of thermal conductivity and charge carrier mobility on individual polar domain structures. , This can help disentangle the effects of the domain boundary from the strain field within domains on phonon and charge carrier transport. However, because of the limitation of methodology, this requires controllably growing the polar domains with a minimum size of 10–20 μm, which has not been observed in GeTe-based materials and requires further investigation.…”

Section: Resultsmentioning

confidence: 99%

“…A potential future study could be implementing local measurement of thermal conductivity and charge carrier mobility on individual polar domain structures. 97,98 This can help disentangle the effects of the domain boundary from the strain field within domains on phonon and charge carrier transport. However, because of the limitation of methodology, this requires controllably growing the polar domains with a minimum size of 10−20 μm, which has not been observed in GeTe-based materials and requires further investigation.…”

Section: Balance Between Weighted Mobility and Latticementioning

confidence: 99%

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Implications and Optimization of Domain Structures in IV–VI High-Entropy Thermoelectric Materials

Liu,

Xie,

et al. 2024

J. Am. Chem. Soc.

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High-entropy semiconductors are now an important class of materials widely investigated for thermoelectric applications. Understanding the impact of chemical and structural heterogeneity on transport properties in these compositionally complex systems is essential for thermoelectric design. In this work, we uncover the polar domain structures in the high-entropy PbGeSnSe 1.5 Te 1.5 system and assess their impact on thermoelectric properties. We found that polar domains induced by crystal symmetry breaking give rise to well-structured alternating strain fields. These fields effectively disrupt phonon propagation and suppress the thermal conductivity. We demonstrate that the polar domain structures can be modulated by tuning crystal symmetry through entropy engineering in PbGeSnAg x Sb x Se 1.5+x Te 1.5+x . Incremental increases in the entropy enhance the crystal symmetry of the system, which suppresses domain formation and loses its efficacy in suppressing phonon propagation. As a result, the roomtemperature lattice thermal conductivity increases from κ L = 0.63 Wm −1 K −1 (x = 0) to 0.79 Wm −1 K −1 (x = 0.10). In the meantime, the increase in crystal symmetry, however, leads to enhanced valley degeneracy and improves the weighted mobility from μ w = 29.6 cm 2 V −1 s −1 (x = 0) to 35.8 cm 2 V −1 s −1 (x = 0.10). As such, optimal thermoelectric performance can be achieved through entropy engineering by balancing weighted mobility and lattice thermal conductivity. This work, for the first time, studies the impact of polar domain structures on thermoelectric properties, and the developed understanding of the intricate interplay between crystal symmetry, polar domains, and transport properties, along with the impact of entropy control, provides valuable insights into designing GeTe-based high-entropy thermoelectrics.

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Section: Resultsmentioning

confidence: 99%

Section: Balance Between Weighted Mobility and Latticementioning

confidence: 99%

Implications and Optimization of Domain Structures in IV–VI High-Entropy Thermoelectric Materials

Liu,

Xie,

et al. 2024

J. Am. Chem. Soc.

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“…Consequently, many devices experience degradation or failure mechanisms that are known to be thermal in nature ( 1 – 3 ), yet pinpointing the precise causes remains very difficult due to the lack of nanoscale thermometry techniques compatible with realistic operating conditions. Materials characterization challenges such as measuring interfacial thermal resistances across individual grains ( 4 , 5 ) or material phases with nanoscale dimensions would also strongly benefit from broadly compatible nanothermometry approaches. Likewise, nanoscale temperature maps can provide direct evidence to verify longstanding predictions of deviations from classical heat transfer laws at the nanoscale ( 6 ).…”

Section: Introductionmentioning

confidence: 99%

Optical super-resolution nanothermometry via stimulated emission depletion imaging of upconverting nanoparticles

Ye,

Harrington,

Pickel

2024

Sci. Adv.

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From engineering improved device performance to unraveling the breakdown of classical heat transfer laws, far-field optical temperature mapping with nanoscale spatial resolution would benefit diverse areas. However, these attributes are traditionally in opposition because conventional far-field optical temperature mapping techniques are inherently diffraction limited. Optical super-resolution imaging techniques revolutionized biological imaging, but such approaches have yet to be applied to thermometry. Here, we demonstrate a super-resolution nanothermometry technique based on highly doped upconverting nanoparticles (UCNPs) that enable stimulated emission depletion (STED) super-resolution imaging. We identify a ratiometric thermometry signal and maintain imaging resolution better than ~120 nm for the relevant spectral bands. We also form self-assembled UCNP monolayers and multilayers and implement a detection scheme with scan times >0.25 μm 2 /min. We further show that STED nanothermometry reveals a temperature gradient across a joule-heated microstructure that is undetectable with diffraction limited thermometry, indicating the potential of this technique to uncover local temperature variation in wide-ranging practical applications.

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“…Recently, spatially resolved thermoreflectance was employed for thermal imaging and measurements of grain boundary thermal resistance in ceria ceramics, polycrystalline diamond, and in a polycrystalline thermoelectric SnTe . The thermoreflectance-based techniques are optical, noncontact, pump–probe methods, where pump (heat sourcing) and probe (temperature sensing) laser spots can coincide or can be placed at different locations over a sample.…”

Section: Introductionmentioning

confidence: 99%

“…The thermoreflectance-based techniques are optical, noncontact, pump–probe methods, where pump (heat sourcing) and probe (temperature sensing) laser spots can coincide or can be placed at different locations over a sample. The laser spot size can be as small as ∼1 μm, and the techniques were used to map thermal conductivity , or oscillations of the temperature field in the vicinity of grain boundaries in the polycrystalline materials. These measurements, achieved with a micrometer-scale spatial resolution, revealed thermal conductivity suppression near grain boundaries , and correlation of grain boundary thermal resistance with the grain misorientation angle. , They represent significant progress in characterizing the heat flow both at and across individual defect entities.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Imaging and Measurements of Grain Boundary Thermal Resistance in Ceramics with Scanning Thermal Wave Microscopy

Alikin,

Pereira,

Abramov

et al. 2024

ACS Appl. Mater. Interfaces

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Material thermal conductivity is a key factor in various applications, from thermal management to energy harvesting. With microstructure engineering being a widely used method for customizing material properties, including thermal properties, understanding and controlling the role of extended phonon-scattering defects, like grain boundaries, is crucial for efficient material design. However, systematic studies are still lacking primarily due to limited tools. In this study, we demonstrate an approach for measuring grain boundary thermal resistance by probing the propagation of thermal waves across grain boundaries with a temperature-sensitive scanning probe. The method, implemented with a spatial resolution of about 100 nm on finely grained Nb-substituted SrTiO 3 ceramics, achieves a detectability of about 2 × 10 −8 K m 2 W −1 , suitable for chalcogenide-based thermoelectrics. The measurements indicated that the thermal resistance of the majority of grain boundaries in the STiO 3 ceramics is below this value. While there are challenges in improving sensitivity, considering spatial resolution and the amount of material involved in the detection, the sensitivity of the scanning probe method is comparable to that of optical thermoreflectance techniques, and the method opens up an avenue to characterize thermal resistance at the level of single grain boundaries and domain walls in a spectrum of microstructured materials.

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Microscale Imaging of Thermal Conductivity Suppression at Grain Boundaries

Cited by 16 publications

References 57 publications

Implications and Optimization of Domain Structures in IV–VI High-Entropy Thermoelectric Materials

Implications and Optimization of Domain Structures in IV–VI High-Entropy Thermoelectric Materials

Optical super-resolution nanothermometry via stimulated emission depletion imaging of upconverting nanoparticles

Nanoscale Imaging and Measurements of Grain Boundary Thermal Resistance in Ceramics with Scanning Thermal Wave Microscopy

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