First-Principles Calculation of Electronic Structure and Properties of Gd Doped La2Ce2O7
The geometric structure,electronic structure and mechanical and thermal properties of(La1-xGdx)2Ce2O7(x was mole fraction with values of 0,0.25,0.50,0.75 and 1.00)were studied with different Gd doping amounts by first-principles calculation based on density functional theory.The results show that the band structure of(La1-xGdx)2Ce2O7 was Γ-Χ indirect band gap,and the band gap decreased with the increase of x.With the increase of x,the lattice constant and volume of(La1-xGdx)2Ce2O7 first decreased and then increased,the relative molecular mass increased,and the density first increased and then decreased.The mechanical properties of(La1-xGdx)2Ce2O7 all agreed with the Born-Huang stability criterion,indicating that(La1-xGdx)2Ce2O7 had good mechanical stability.The Pugh's ratio(ratio of shear modulus to bulk modulus)was less than 0.571,and the Poisson's ratio was greater than 0.26,indicating that(La1-xGdx)2Ce2O7 had good toughness and could withstand thermal cycling stress.The minimum thermal conductivity of(Lai-xGdx)2Ce2O7 ranged from 0.98 W·mi-1·K-1 to 1.26 W·mn-1·K-1,which was lower than that of yttria-stabilized zirconia,indicating that(La1-xGdx)2Ce2O7 had good thermal properties and could be used as a candidate material for thermal barrier coatings.
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