Using the solid-state reaction method, the (ZrO2)x-(Dy3TaO7)1−x (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1) ceramics are synthesized in this work. The identification of the crystal structures indicates that the (ZrO2)x-(Dy3TaO7)1−x ceramics belong to the orthorhombic system, and the space group is C2221 in spite of the value of x increasing to 0.1. The thermal conductivities of the (ZrO2)x-(Dy3TaO7)1−x ceramics range from 1.3 W/(m K) to 1.8 W/(m K), and this value is much lower than that of 7-8 YSZ (yttria-stabilized zirconia). Besides, the (ZrO2)x-(Dy3TaO7)1−x ceramics possess the glass-like thermal conductivity caused by intrinsic oxygen vacancies existing in the lattice of Dy3TaO7. Moreover, the results of thermal expansion rates demonstrate that the (ZrO2)x-(Dy3TaO7)1−x ceramics possess excellent high temperature phase stability, and the thermal expansion coefficients [(9.7–11) × 10−6 K−1] are comparable to that of 7-8 YSZ.
To elucidate the structure-performance relationship of the new potential cathode materials AFe(SO 4 ) 2 (A = Li, Na, K) compared with LiFePO 4 , first-principles calculations are performed to investigate the structure, mechanical stabilities and electronic properties of them. The calculated results show that AFe(SO 4 ) 2 (A = Li, Na, K) compounds are mechanically stable and exhibit strong anisotropy. LiFe(SO 4 ) 2 , NaFe(SO 4 ) 2 and KFe(SO 4 ) 2 are more brittle and have higher elastic modulus than LiFePO 4 , which is attributed to the strong chemical bonding of them. Electronic structure are predicted by HSE06 functional and the band gaps are 5.006, 4.996, 5.146 and 3.711 eV for LiFe(SO 4 ) 2 , NaFe(SO 4 ) 2 , KFe(SO 4 ) 2 and LiFePO 4 , respectively. Full ab initio molecular dynamics simulations are performed to calculate the mean square displacements and diffusion coefficients of the alkali-ion. NaFe(SO 4 ) 2 has large diffusion coefficient as 90.1×10 −11 m 2 /s at 1273 K, as well as larger activation energy as 0.167 eV. All the results contribute to understand the microscopic origin of the different behaviors of intercalation cathode used in rechargeable battery.
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