“…The g was derived by linearly fitting the data: g = 5.5(± 0.2) and 5.5(± 0.5) for B1 and B2 phase, respectively. Our g values are in reasonable agreement with theoretical estimates 32 , 35 , while larger than those reported in Ref. 32 where the g value was determined by only two experimental data points in each phase.…”
Section: Resultssupporting
confidence: 92%
“…The reduction of thermal conductivity across the B1–B2 transition, almost 70%, is in reasonable agreement with those modeled using several simple interatomic potentials 33 , but much larger than that reported in Ref. 32 (only ~ 37%), where the reduction was not sampled right across the phase transition. Figure 1 Pressure dependence of the thermal conductivity of NaCl at room temperature.…”
Section: Resultssupporting
confidence: 89%
“…Though recently McGuire et al . 32 reported relative changes in NaCl’s thermal conductivity as a function of relative density across the B1–B2 transition, a precise determination of the thermal conductivity values at high P–T conditions remains unavailable. Lack of such critical data may lead to inaccurate modeling of the temperature evolution in laser-heated or externally-heated DAC experiments, which in turn could give rise to inaccurate thermal conductivity of the sample of interest.…”
Sodium chloride (NaCl) is an important, commonly used pressure medium and pressure calibrant in diamond-anvil cell (DAC) experiments. Its thermal conductivity at high pressure–temperature (P–T) conditions is a critical parameter to model heat conduction and temperature distribution within an NaCl-loaded DAC. Here we couple ultrafast optical pump-probe methods with the DAC to study thermal conductivity and compressional velocity of NaCl in B1 and B2 phase to 66 GPa at room temperature. Using an externally-heated DAC, we further show that thermal conductivity of NaCl-B1 phase follows a typical T−1 dependence. The high P–T thermal conductivity of NaCl enables us to confirm the validity of Leibfried-Schlömann equation, a commonly used model for the P–T dependence of thermal conductivity, over a large compression range (~ 35% volume compression in NaCl-B1 phase, followed by ~ 20% compression in the polymorphic B2 phase). The compressional velocities of NaCl-B1 and B2 phase both scale approximately linearly with density, indicating the applicability of Birch’s law to NaCl within the density range we study. Our findings offer critical insights into the dominant physical mechanism of phonon transport in NaCl, as well as important data that significantly enhance the accuracy of modeling the spatiotemporal evolution of temperature within an NaCl-loaded DAC.
“…The g was derived by linearly fitting the data: g = 5.5(± 0.2) and 5.5(± 0.5) for B1 and B2 phase, respectively. Our g values are in reasonable agreement with theoretical estimates 32 , 35 , while larger than those reported in Ref. 32 where the g value was determined by only two experimental data points in each phase.…”
Section: Resultssupporting
confidence: 92%
“…The reduction of thermal conductivity across the B1–B2 transition, almost 70%, is in reasonable agreement with those modeled using several simple interatomic potentials 33 , but much larger than that reported in Ref. 32 (only ~ 37%), where the reduction was not sampled right across the phase transition. Figure 1 Pressure dependence of the thermal conductivity of NaCl at room temperature.…”
Section: Resultssupporting
confidence: 89%
“…Though recently McGuire et al . 32 reported relative changes in NaCl’s thermal conductivity as a function of relative density across the B1–B2 transition, a precise determination of the thermal conductivity values at high P–T conditions remains unavailable. Lack of such critical data may lead to inaccurate modeling of the temperature evolution in laser-heated or externally-heated DAC experiments, which in turn could give rise to inaccurate thermal conductivity of the sample of interest.…”
Sodium chloride (NaCl) is an important, commonly used pressure medium and pressure calibrant in diamond-anvil cell (DAC) experiments. Its thermal conductivity at high pressure–temperature (P–T) conditions is a critical parameter to model heat conduction and temperature distribution within an NaCl-loaded DAC. Here we couple ultrafast optical pump-probe methods with the DAC to study thermal conductivity and compressional velocity of NaCl in B1 and B2 phase to 66 GPa at room temperature. Using an externally-heated DAC, we further show that thermal conductivity of NaCl-B1 phase follows a typical T−1 dependence. The high P–T thermal conductivity of NaCl enables us to confirm the validity of Leibfried-Schlömann equation, a commonly used model for the P–T dependence of thermal conductivity, over a large compression range (~ 35% volume compression in NaCl-B1 phase, followed by ~ 20% compression in the polymorphic B2 phase). The compressional velocities of NaCl-B1 and B2 phase both scale approximately linearly with density, indicating the applicability of Birch’s law to NaCl within the density range we study. Our findings offer critical insights into the dominant physical mechanism of phonon transport in NaCl, as well as important data that significantly enhance the accuracy of modeling the spatiotemporal evolution of temperature within an NaCl-loaded DAC.
“…[ 154 ] proposed a pressure thermal switch based on the B1 (face‐centered cubic) to B2 (body‐centered cubic) phase transition in NaCl. [ 154 ] Originally, this structure was not presented as a thermal switch, but the data of the changes in the thermal conductivity were equal to a switching ratio of ≈1.6. [ 154 ]…”
Section: Thermal Switchesmentioning
confidence: 99%
“…[ 154 ] Originally, this structure was not presented as a thermal switch, but the data of the changes in the thermal conductivity were equal to a switching ratio of ≈1.6. [ 154 ]…”
Over the past decade, solid‐state thermal control devices have emerged as potential candidates for enhanced thermal management and storage. They distinguish themselves from traditional passive thermal management devices in that their thermal properties have sharp, nonlinear dependencies on direction and operating temperature, and can lead to more efficient circuits and energy conversion systems than what is possible today. They also distinguish themselves from traditional active thermal management devices (e.g., fans) in that they have no moving parts and are compact and reliable. In this article, the recent progress in the four broad categories of solid‐state thermal control devices that are under active research is reviewed: diodes, switches, regulators, and transistors. For each class of device, the operation principle, material choices, as well as metrics to compare and contrast performance are discussed. New architectures that are explored theoretically, but not experimentally demonstrated, are also discussed.
Growing technical demand for thermal management stems from the pursuit of high–efficient energy utilization and the reuse of wasted thermal energy, which necessitates the manipulation of heat flow with electronic analogs to improve device performance. Here, recent experimental progress is reviewed for thermal switching materials, aiming to achieve all–solid–state thermal switches, which are an enabling technology for solid–state thermal circuits. Moreover, the current understanding for discovering thermal switching materials is reshaped from the aspect of heat conduction mechanisms under external controls. Furthermore, current challenges and future perspectives are provided to highlight new and emerging directions for materials discovery in this continuously evolving field.
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