摘要
Thermal barrier coating(TBC)materials can improve energy conversion efficiency and reduce fossil fuel use.Herein,novel rare earth tantalates RETaO_(4),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 RETaO_(4)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¯3+RE/r5+Ta 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.
基金
supported by the National Key R&D Program of China(No.2022YFB3708600)
the Materials Genome Engineering of Rare and Precious Metal of Yunnan Province(No.202102AB080019-1)
Yunnan Fundamental Research Projects(Nos.202101AW070011,202101BE070001-015)
Kunming University of Science and Technology Analysis and Testing Fund(No.2022P20211130017).
