La2Ce2O7 (LCO) is a promising candidate for thermal barrier coatings (TBCs) due to that it provides better thermal insulation than yttria-stabilized zirconia (YSZ) does. In this work, a TBC LCO was produced by solutio...La2Ce2O7 (LCO) is a promising candidate for thermal barrier coatings (TBCs) due to that it provides better thermal insulation than yttria-stabilized zirconia (YSZ) does. In this work, a TBC LCO was produced by solution precursor plasma spraying (SPPS). After the solution precursors were prepared and the spraying parameters were optimized, the thermophysical properties and thermal shock performance of the coatings were tested. It was found that the SPPS coating with segmentation crack density of 6 mm^-1 had the porosities of about 33.5% at spray distances of 35 mm. The thermal conductivity of the SPPS coatings is 0.50-0.75 W·m^-1·K^-1, much lower than that of the atmospheric plasma spraying (APS) coatings (0.85-1.25 W·m^-1·K^-1). The thermal shock performance of the SPPS coatings reached 60 cycles, much better than the APS coatings. This improvement is due to the segmentation cracks in the coatings, which can improve strain tolerance and effectively relieve internal stress. This study provides reference significance for further research on thermal barrier coatings.展开更多
We investigate the structural and elastic properties of hexagonal Ce2O3 under pressure using LDA＋U scheme in the frame of density functional theory （DFT）. The obtained lattice constants and bulk modulus agree well ...We investigate the structural and elastic properties of hexagonal Ce2O3 under pressure using LDA＋U scheme in the frame of density functional theory （DFT）. The obtained lattice constants and bulk modulus agree well with the available experimental and other theoretical data. The pressure dependences of normalized lattice parameters a/ao and c/co, ratio c/a, and normalized primitive volume V/Vo of Ce2O3 are obtained. Moreover, the pressure dependences of elastic properties and three anisotropies of elastic waves of Ce2O3 are investigated for the first time. We find that the negative value of Ca4 is indicative of the structural instability of the hexagonal structure Ce2O3 at zero temperature and 30 GPa. Finally, the density of states （DOS） of Ce2O3 under pressure is investigated.展开更多
We investigated the structure and thermodynmnic properties of the hexagonal Ce2O3 by using LDA＋U scheme in the fi＇ame of density functional theory （DFT）, together with the quasi-harmonic Debye model. The obtained ...We investigated the structure and thermodynmnic properties of the hexagonal Ce2O3 by using LDA＋U scheme in the fi＇ame of density functional theory （DFT）, together with the quasi-harmonic Debye model. The obtained lattice constants, bulk modulus, and the insulating gap agree well with the available experimental data. We successfully yielded the temperature dependence of bulk modulus, volume, thermal expansion coefficient, Debye temperature, specific heat as well as the entropy at different U values. It is found that the introduction of the U value cannot only correct the calculation of the structure but also improve the accurate description of the thermodynamic properties of Ce2Oa. When U = 6 eV the calculated volume （538 Bohra） at 300 K agrees well with the experimental value （536 Bohr3）. The calculated entropy curve becomes more and more close to the experimental curve, with the increasing U value.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51571002 and 51401003)Beijing Municipal Natural Science Foundation(Nos. 2172008 and KZ201310005003)
文摘La2Ce2O7 (LCO) is a promising candidate for thermal barrier coatings (TBCs) due to that it provides better thermal insulation than yttria-stabilized zirconia (YSZ) does. In this work, a TBC LCO was produced by solution precursor plasma spraying (SPPS). After the solution precursors were prepared and the spraying parameters were optimized, the thermophysical properties and thermal shock performance of the coatings were tested. It was found that the SPPS coating with segmentation crack density of 6 mm^-1 had the porosities of about 33.5% at spray distances of 35 mm. The thermal conductivity of the SPPS coatings is 0.50-0.75 W·m^-1·K^-1, much lower than that of the atmospheric plasma spraying (APS) coatings (0.85-1.25 W·m^-1·K^-1). The thermal shock performance of the SPPS coatings reached 60 cycles, much better than the APS coatings. This improvement is due to the segmentation cracks in the coatings, which can improve strain tolerance and effectively relieve internal stress. This study provides reference significance for further research on thermal barrier coatings.
文摘We investigate the structural and elastic properties of hexagonal Ce2O3 under pressure using LDA＋U scheme in the frame of density functional theory （DFT）. The obtained lattice constants and bulk modulus agree well with the available experimental and other theoretical data. The pressure dependences of normalized lattice parameters a/ao and c/co, ratio c/a, and normalized primitive volume V/Vo of Ce2O3 are obtained. Moreover, the pressure dependences of elastic properties and three anisotropies of elastic waves of Ce2O3 are investigated for the first time. We find that the negative value of Ca4 is indicative of the structural instability of the hexagonal structure Ce2O3 at zero temperature and 30 GPa. Finally, the density of states （DOS） of Ce2O3 under pressure is investigated.
基金The authors would like to thank the support by the National Natural Science Foundation of China （Grant Nos. 11204192 and 61176096）. We also acknowledge the support for the eomputational resources by the State Key Laboratory of Poly mer Materials Engineering of China in Sichuan University. Some calculations are performed on the ScGrid of Supercomputing Center, Computer Network Information Center of Chinese Academyof Sciences.
文摘We investigated the structure and thermodynmnic properties of the hexagonal Ce2O3 by using LDA＋U scheme in the fi＇ame of density functional theory （DFT）, together with the quasi-harmonic Debye model. The obtained lattice constants, bulk modulus, and the insulating gap agree well with the available experimental data. We successfully yielded the temperature dependence of bulk modulus, volume, thermal expansion coefficient, Debye temperature, specific heat as well as the entropy at different U values. It is found that the introduction of the U value cannot only correct the calculation of the structure but also improve the accurate description of the thermodynamic properties of Ce2Oa. When U = 6 eV the calculated volume （538 Bohra） at 300 K agrees well with the experimental value （536 Bohr3）. The calculated entropy curve becomes more and more close to the experimental curve, with the increasing U value.
