Electrical Properties of Li+-Substituted Solid Solutions Based on Gd2Zr2O7

Abstract

Solid solution $${\text{G}}{{{\text{d}}}_{{2 - x}}}{\text{L}}{{{\text{i}}}_{x}}{\text{Z}}{{{\text{r}}}_{2}}{{{\text{O}}}_{{7 - x}}}$$ with a pyrochlore structure is synthesized for the first time. The cationic composition is confirmed via chemical analysis and nuclear reactions. It is found that the stoichiometry with respect to lithium is retained up to 1100°C. The lattice parameter diminishes in the homogeneity range 0 ≤ x ≤ 0.30, while the free volume of migration grows. Introducing lithium into the Gd sublattice raises oxygen–ion conductivity, due to the emergence of oxygen vacancies and enhancement of their mobility. Maximum conductivity is reached for composition with х = 0.10 (~1 × 10−3 Ω−1 cm−1, 650°C). An assumption is made about the formation of associates of the type $${{\{ {\text{Li}}_{{{\text{Gd}}}}^{{''}} \cdot {\text{V}}_{{\text{o}}}^{{ \bullet \bullet }}\} }^{ \times }}$$ at high contents of the dopant (x = 0.30), accompanied by an increase in the activation energy of conductivity.

The Gd2−xMgxZr2O7−x/2 Solid Solution: Ionic Conductivity and Chemical Stability in the Melt of LiCl-Li2O

“…Ca 2+ -doping of GdSmZr 2 O 7 [48] and Gd 2 Zr 2 O 7 [33] also did not lead to an increase in conductivity. For Li + -doped solid solution Gd 2−x Li x Zr 2 O 7−x , it was shown that although the lattice parameter decreased with doping, the free volume increased [49]. This led to an increase in ionic conductivity at low dopant concentrations up to one order of magnitude.…”

Equilibrium of intrinsic and impurity point defects in Ca-doped Sm2Zr2O7

“…Due to their good thermomechanical characteristics, compositions such as Gd 2 Zr 2 O 7 , and (La 1−x Gd x ) 2 Zr 2 O 7 are recommended as thermal barrier coating materials [1][2][3][4][5][6], which is one of the promising applications of pyrochlores. Having high chemical stability, pyrochlores are used as electrolytes for oxygen sensors for aggressive environments, such as Li-based melts [7][8][9]. High radiation resistance allows pyrochlores to be used as materials for the encapsulation of nuclear waste [10,11].…”

Electrical Properties and Chemical Resistance of the Composites (1-x)Gd2Zr2O7·xMgO in Li-Containing Chloride Melts

“…For this purpose, it is necessary to determine the range of dopants that can ensure the acquisition of a high-density ceramic material with high, dominant oxygen ion conductivity. Previously, it was found that the use of lithium as a dopant for the Gd 2 Zr 2 O 7 phase makes it possible to increase the oxygen ion conductivity but does not make it possible to obtain high-density ceramics [29,30]. Therefore, the problem of searching for dopants for the Gd 2 Zr 2 O 7 phase remains relevant.…”