High-entropy(HE)ultra-high temperature ceramics have the chance to pave the way for future applications propelling technology advantages in the fields of energy conversion and extreme environmental shielding.Among oth...High-entropy(HE)ultra-high temperature ceramics have the chance to pave the way for future applications propelling technology advantages in the fields of energy conversion and extreme environmental shielding.Among others,HE diborides stand out owing to their intrinsic anisotropic layered structure and ability to withstand ultra-high temperatures.Herein,we employed in-situ high-resolution synchrotron diffraction over a plethora of multicomponent compositions,with four to seven transition metals,with the intent of understanding the thermal lattice expansion following different composition or synthesis process.As a result,we were able to control the average thermal expansion(TE)from 1.3×10^(−6)to 6.9×10^(−6)K^(−1)depending on the combination of metals,with a variation of in-plane to out-of-plane TE ratio ranging from 1.5 to 2.8.展开更多
In this paper,(Gd_(1−x)Y_(x))TaO_(4) ceramics have been fabricated by solid-phase synthesis reaction.Each sample was found to crystallize in a monoclinic phase by X-ray diffraction(XRD).The properties of(Gd_(1−x)Y_(x)...In this paper,(Gd_(1−x)Y_(x))TaO_(4) ceramics have been fabricated by solid-phase synthesis reaction.Each sample was found to crystallize in a monoclinic phase by X-ray diffraction(XRD).The properties of(Gd_(1−x)Y_(x))TaO_(4) were optimized by adjusting the ratio of Gd/Y.(Gd_(1−x)Y_(x))TaO_(4) had a low high-temperature thermal conductivity(1.37–2.05 W·m^(−1)·K^(−1)),which was regulated by lattice imperfections.The phase transition temperature of the(Gd_(1−x)Y_(x))TaO_(4) ceramics was higher than 1500℃.Moreover,the linear thermal expansion coefficients(TECs)were 10.5×10^(−6) K^(−1)(1200℃),which was not inferior to yttria-stabilized zirconia(YSZ)(11×10^(−6) K^(−1),1200℃).(Gd_(1−x)Y_(x))TaO_(4) had anisotropic thermal expansion.Therefore,controlling preferred orientation could minimize the TEC mismatch when(Gd_(1−x)Y_(x))TaO_(4) coatings were deposited on different substrates as thermal barrier coatings(TBCs).Based on their excellent properties,it is believed that the(Gd_(1−x)Y_(x))TaO_(4) ceramics will become the next generation of high-temperature thermal protective coatings.展开更多
基金financial support for the XRPD experiments (proposals nr. 20200101 and 20210215)supported by the U.S. National Science Foundation through Grant CMMI-1902069
文摘High-entropy(HE)ultra-high temperature ceramics have the chance to pave the way for future applications propelling technology advantages in the fields of energy conversion and extreme environmental shielding.Among others,HE diborides stand out owing to their intrinsic anisotropic layered structure and ability to withstand ultra-high temperatures.Herein,we employed in-situ high-resolution synchrotron diffraction over a plethora of multicomponent compositions,with four to seven transition metals,with the intent of understanding the thermal lattice expansion following different composition or synthesis process.As a result,we were able to control the average thermal expansion(TE)from 1.3×10^(−6)to 6.9×10^(−6)K^(−1)depending on the combination of metals,with a variation of in-plane to out-of-plane TE ratio ranging from 1.5 to 2.8.
基金supported by the National Natural Science Foundation of China(No.91960103)the Yunnan Province Science Fund for Distinguished Young Scholars(No.2019FJ006)Rare and Precious Metals Material Genetic Engineering Project of Yunnan Province(No.202102AB080019-1).
文摘In this paper,(Gd_(1−x)Y_(x))TaO_(4) ceramics have been fabricated by solid-phase synthesis reaction.Each sample was found to crystallize in a monoclinic phase by X-ray diffraction(XRD).The properties of(Gd_(1−x)Y_(x))TaO_(4) were optimized by adjusting the ratio of Gd/Y.(Gd_(1−x)Y_(x))TaO_(4) had a low high-temperature thermal conductivity(1.37–2.05 W·m^(−1)·K^(−1)),which was regulated by lattice imperfections.The phase transition temperature of the(Gd_(1−x)Y_(x))TaO_(4) ceramics was higher than 1500℃.Moreover,the linear thermal expansion coefficients(TECs)were 10.5×10^(−6) K^(−1)(1200℃),which was not inferior to yttria-stabilized zirconia(YSZ)(11×10^(−6) K^(−1),1200℃).(Gd_(1−x)Y_(x))TaO_(4) had anisotropic thermal expansion.Therefore,controlling preferred orientation could minimize the TEC mismatch when(Gd_(1−x)Y_(x))TaO_(4) coatings were deposited on different substrates as thermal barrier coatings(TBCs).Based on their excellent properties,it is believed that the(Gd_(1−x)Y_(x))TaO_(4) ceramics will become the next generation of high-temperature thermal protective coatings.
