Volume 1, Issue 1 by Thermo -X
Thermo-X, 2025
Antiperovskites have attracted significant interest in the field of energy conversion in recent y... more Antiperovskites have attracted significant interest in the field of energy conversion in recent years. While extensive research has focused on the magnetism, ionic conductivity and superconductivity of antiperovskites, their thermal properties including lattice anharmonicity and thermal transport remain less explored compared to their well-studied perovskite counterparts. Recently, nitrohalide double antiperovskites have been successfully synthesized. In this work, we investigate the thermal transport properties of nitrohalide double antiperovskites Li6NII2 and Li6NBrBr2 using first-principles machine-learning potentials. Our results reveal that within the perturbation theory framework, imaginary phonons appear throughout the entire Brillouin zone in both the harmonic regime and at elevated temperatures. Atomic vibrational analysis indicates that stochastic Li-ion movements confined within a single conventional unit cell are responsible for the presence of these imaginary phonons. Furthermore, homogeneous nonequilibrium molecular dynamics and equilibrium molecular dynamics simulations demonstrate that Li6NII2 and Li6NBrBr2 exhibit ultralow glass-like lattice thermal conductivities. Spectral thermal conductivity analysis shows that the dominant contributions arise from phonons with frequencies below 5 THz and around 11 THz. The substantial phonon contribution near 11 THz is attributed to the confined stochastic motions of Li ions. This work uncovers the unconventional microscopic cation dynamics and strong lattice anharmonicity in double antiperovskites Li6NII2 and Li6NBrBr2, thereby advancing the understanding of phonon transport in these materials.
Thermo-X, 2025
With the continuous miniaturization of micro-devices and the rapid advancement of novel nanomater... more With the continuous miniaturization of micro-devices and the rapid advancement of novel nanomaterials, thermal characterization techniques tailored for two-dimensional (2D) structures (films and coatings) and one-dimensional (1D) architectures (wires and fibers) have become essential for elucidating structure-property relationships and optimizing material performance. This review provides an in-depth analysis of the Transient Electro-Thermal (TET) technique, a recently developed method for measuring the thermal diffusivity and conductivity of 1D and 2D materials, including dielectric, metallic, and semiconductive films, coatings, and wires/fibers. We discuss the fundamental principles of TET operation, the associated physical and mathematical models for data reduction, and critical methodologies for data fitting, uncertainty analysis, and stray heat transfer mitigation to ensure high repeatability and accuracy. In addition, the latest developments and applications of TET are highlighted, including its extension to atomic-scale thickness, in-situ dynamic thermal property measurements during structural evolution, and the zero-temperature-rise limit method. The outstanding agreement (within ~0.6%) between the measured and reference thermal diffusivity of a Pt wire, validated through extensive experiments and zero-temperature-rise extrapolation, demonstrates the robustness and reliability of the TET technique. Owing to its simplicity in principles, experimental implementation, and data analysis, TET offers significant advantages in uncertainty control, measurement accuracy, and throughput.
Thermo-X, 2025
Enhancing indoor visual comfort is crucial for the practical deployment of thermochromic smart wi... more Enhancing indoor visual comfort is crucial for the practical deployment of thermochromic smart windows. However, their application is often hindered by the low visible light transmittance (T lum) in the activated state. In this study, we propose a thermally and optically dual-responsive smart window that improves both building energy efficiency and T lum in the activated state. The design is based on a polyacrylamide (PAm)/poly(N-isopropylacrylamide) (PNIPAm)/indium tin oxide (ITO) composite film (PPI). Within this structure, PAm provides a hydrophilic matrix, PNIPAm microgels enable thermoresponsive optical modulation through reversible transmittance changes across the response temperature, and ITO particles act as light-to-heat transducers due to their photothermal and infrared reflective properties. Compared with the PNIPAm hydrogel film, the PPI composite film increases T lum in the activated state from 9.7% to 50.0% and enhances infrared modulation capability from 39.2% to 50.4%. Under an illumination intensity of 95 mW cm-2 , the PPI composite film lowers the indoor temperature of simulated buildings by up to 7 °C. This dual-responsive thermochromic window provides improved indoor visual comfort along with effective temperature regulation, offering a promising strategy for advancing the practical use of smart windows.
Thermo-X, 2025
The electrocaloric (EC) effect represents the changes of polarization entropy and/or temperature ... more The electrocaloric (EC) effect represents the changes of polarization entropy and/or temperature of dielectrics when an external electric field is applied and removed. An efficient EC effect relies on a highly reversible conversion between electrical energy and thermal energy. Based on this effect, EC refrigeration has demonstrated advantages in terms of high energy efficiency, zero direct carbon emissions, and high specific volumetric cooling power densities. Consequently, EC refrigeration is recognized as one of the promising alternative technologies for next-generation refrigeration and heat pump. Over the past two decades, EC cooling devices have been extensively developed, driven by advances in EC materials and working bodies. In this review, we summarize recent progress in EC cooling devices, focusing on the mechanisms of solid-state refrigerants and thermodynamic cycles within these systems, and highlighting the characteristics of devices operating on different working principles.
Thermo-X, 2025
Phase change materials possess significant potential for solar-thermal energy storage yet face cr... more Phase change materials possess significant potential for solar-thermal energy storage yet face critical limitations, including structural instability, inherently poor heat conductivity, and inadequate solar absorption, thereby constraining their practical applications. To address these challenges, we developed a laminated phase change composite (PCC) via pressure-assisted lamination of paraffin wax-olefin block copolymer (PW-OBC) with expanded graphite (EG) sheets. Experiments indicate that the OBC in the well-mixed PW-OBC sheet forms a three-dimensional network that encases the PW, enabling excellent leakage resistance, thermal/cyclic durability, and shape stability. The parallel EG sheets establish directional and continuous heat transport channels, resulting in 4.54 W•m-1 •K-1 lengthwise heat conductivity versus a transverse value of 0.49 W•m-1 •K-1 , with an excellent thermal conductive anisotropy of 9.27. Coating the PCC surface with carbon black enhances its solar irradiation absorption, yielding a solar absorptivity of 0.98. Benefiting from the synergy of anisotropic heat conduction and enhanced solar absorption, the PCC can attain 79.2%-96.5% solar-thermal efficiency within 1-3 suns irradiance, enabling effective solar energy capture and storage. These results provide a viable approach for producing high-performance, anisotropically conductive PCCs for efficient low-to medium-temperature solar-thermal applications.
Thermo-X, 2025
Heat is the oldest and most ubiquitous form of energy in the universe: from the nuclear fusion of... more Heat is the oldest and most ubiquitous form of energy in the universe: from the nuclear fusion of stars to the metabolism of living organisms, and from the steam engines to the heat dissipation of microchips. The transfer, conversion, and regulation of heat have run through the course of natural evolution and the footprint of human civilization . Thermodynamics has laid the cornerstone of modern industry . From Fourier's heat conduction equation to Planck's law of black-body radiation , exploration of "heat" has always driven the deepening of scientific understanding and the progress of civilization . In today's era of rapid technological development, thermal science has been integrated into cutting-edge fields such as quantum technology , artificial intelligence (AI) , intelligent materials , and life sciences with unprecedented depth and breadth, demonstrating strong interdisciplinary and transformative characteristics (Figure ).
Volume 2, Issue 1 by Thermo -X
Thermo-X, 2026
Effective thermal management is crucial for global sustainability, yet it faces a fundamental cha... more Effective thermal management is crucial for global sustainability, yet it faces a fundamental challenge: traditional materials cannot dynamically regulate the three coupled heat transfer modes, namely conduction, convection, and radiation, in complex, real-world environments. To overcome this, we present a paradigm shift from material selection to the architectural design of synergistic heat transfer. This perspective explores how multimodal thermal metamaterials, through engineered microstructures and topology, enable programmable control over coupled thermal flows. We highlight how this approach yields advanced functionalities, including directional guidance, adaptive cooling, and waste-heat recovery, across scales ranging from microelectronics to buildings and marine systems. This architectural design framework transcends intrinsic material limits, establishing a foundational pathway toward intelligent, high-efficiency, and sustainable thermal technologies essential for energy sustainability.
Thermo-X, 2026
The increasing die size, package dimensions and operating heat flux of AI chips impose stringent ... more The increasing die size, package dimensions and operating heat flux of AI chips impose stringent requirements on the mechanical compliance and reliability of chip-level thermal interface materials (TIMs). Polymer-based TIMs, particularly silicone gels, offer advantages such as mechanical flexibility, automated dispensability, and warpage accommodation in large packages; however, their application is limited by weak interfacial adhesion and siloxane volatilization. Therefore, it is essential to develop advanced non-silicone thermal gels. This study reports a poly(ionic liquid) (PIL)-based thermally gel TIM. The TIM was fabricated by dispensing a mixture of ionic liquid monomer, Al 2 O 3 thermal filler, and initiator, followed by thermal curing, making it compatible with FCBGA dispensing processes (the viscosity before curing was 225 Pa•s). With 70 vol% Al 2 O 3 filler, the PIL-based TIM exhibited a low storage modulus of 255 kPa and high interfacial adhesion strengths of 0.95 MPa to Cu and 0.91 MPa to Si. The intrinsic thermal resistance reached 2.4 × 10-5 m 2 •K/W, comparable to that of conventional silicone systems. Notably, the interfacial contact thermal resistance with Si (R c = 1.95 ± 0.87 × 10-7 m 2 •K/W) was an order of magnitude lower than that of silicone-based TIMs. Reliability tests showed > 98% coverage after three accelerated aging tests, with no leakage or volatilization. The proof-of-concept study validates the feasibility of PIL-based TIMs and highlights their significant potential for further optimization in next-generation AI thermal management.
Thermo-X, 2026
We investigate how metallic rattling modes in Sr 2 HgSn simultaneously suppress particle-like (κ ... more We investigate how metallic rattling modes in Sr 2 HgSn simultaneously suppress particle-like (κ p) and enhance wave-like (κ c) thermal conductivity via a combined first-principles, force-constant modulation, and Wigner transport analysis. Weak Hg-Sn bonds generate flat phonon bands that relax momentum conservation, intensifying both three-and four-phonon scattering and shortening phonon lifetimes. This dual scattering-coherence mechanism reveals a frequency-selective κ p-κ c crossover, leading to a weak temperature-dependent κ L. Our work establishes rattling as a tunable design strategy for controlling phonon transport in thermoelectrics. 
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Volume 1, Issue 1 by Thermo -X
Volume 2, Issue 1 by Thermo -X