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Thermal barrier coating (TBC) materials can improve energy conversion efficiency and reduce fossil fuel use. Herein, novel rare earth tantalates RETaO4, as promising candidates for TBCs, were reassembled into multi-component solid solutions with a monoclinic structure to further depress thermal conductivity via an entropy strategy. The formation mechanisms of oxygen vacancy defects, dislocations, and ferroelastic domains associated with the thermal conductivity are demonstrated by aberration-corrected scanning transmission electron microscopy. Compared to single-RE RETaO4 and 8YSZ, the intrinsic thermal conductivity of (5RE1/5)TaO4 was decreased by 35%–47% and 57%–69% at 1200 ℃, respectively, which is likely attributed to multi-scale phonon scattering from Umklapp phonon–phonon, point defects, domain structures, and dislocations. r¯RE3+/rTa5+ and low-temperature thermal conductivity are negatively correlated, as are the ratio of elastic modulus to thermal conductivity (E/κ) and high-temperature thermal conductivity. Meanwhile, the high defects’ concentration and lattice distortion in high-entropy ceramics enhance the scattering of transverse-wave phonons and reduce the transverse-wave sound velocity, leading to a decrease in the thermal conductivity and Young’s modulus. In addition, 5HEC-1 has ultra-low thermal conductivity, moderate thermal expansion coefficients, and high hardness among three five-component high-entropy samples. Thus, 5HEC-1 with superior thermal barrier and mechanical properties can be used as promising thermal insulating materials.

The foremost objective of this work is to employ an entropy strategy to optimize the thermophysical properties of rare-earth (RE) tantalates. The stabilizing single-phase structure of seven-component rare-earth tantalates is verified by density functional theory calculations, and entropy-stabilized (7RE 1/7)TaO 4 with a defective structure is successfully synthesized via spark plasma sintering. (7RE 1/7)TaO 4 exhibits lower intrinsic thermal conductivity over the entire temperature range from 100 to 1200 °C. Furthermore, its intrinsic thermal conductivity (0.83–0.90 W m−1·K−1) is 39–51% and 68–71% lower compared to those of single-RE RETaO 4 and 8YSZ at 1200 °C, respectively, and is even close to the limited thermal conductivity from the Cahill model. This is the result of multiscale phonon scattering by Umklapp phonon-phonon, point defect, dislocation, ferroelastic domain and distorted structures. Moreover, (7RE 1/7)TaO 4 exhibits superior high-temperature phase stability and excellent mechanical properties. Therefore, entropy-stabilized (7RE 1/7)TaO 4 compounds with ultralow thermal conductivity can be used as promising thermal insulating materials. [ABSTRACT FROM AUTHOR]

The study seeks to provide a deeper insight and strategies into the carbon trading market, the internal mechanism, and the linkage mechanism for emission reduction in the carbon trading market right from its inception. The study differs from most prior research on carbon trading, as this current paper incorporates the carbon market with the dissipative structure theory. Based on the dissipative structure theory, this study adapts the entropy generation principle as the base for the carbon trading market. The study captures the following key dimensions: the change of carbon market value, the entropy generation principle of carbon quota trading process, and the replacement process involved in production factors in carbon trading. The study revealed that the entropy generation of the carbon trading market is mainly caused by the cost gradient formed as a result of the cost difference of emission reduction and the increase of production factor input required by economic development. Moreover, the study revealed clearly the dynamics of the entropy index and the carbon market emission reduction efficiency. Thus, the lower the entropy value of the carbon market, the higher the emission reduction efficiency. [ABSTRACT FROM AUTHOR]