Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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Preparation and Characterization of Ta-substituted Li7La3Zr2-xO12 Garnet Solid Electrolyte by Sol-Gel Processing

  • Yoon, Sang A (Department of Advanced Materials Engineering, Korea Polytechnic University) ;
  • Oh, Nu Ri (Department of Advanced Materials Engineering, Korea Polytechnic University) ;
  • Yoo, Ae Ri (Department of Advanced Materials Engineering, Korea Polytechnic University) ;
  • Lee, Hee Gyun (Department of Advanced Materials Engineering, Korea Polytechnic University) ;
  • Lee, Hee Chul (Department of Advanced Materials Engineering, Korea Polytechnic University)
  • Received : 2017.04.10
  • Accepted : 2017.06.19
  • Published : 2017.07.31
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Abstract

In this work, Ta-substituted $Li_7La_3Zr_{2-x}O_{12}$ (LLZTO) powder and pellets with garnet cubic structure were fabricated and characterized by modified and optimized sol-gel synthesis. Ta-substituted LLZO powder with the smallest grain size and pure cubic structure with little pyrochlore phase was obtained by synthesis method in which Li and La sources in propanol solvent were mixed together with Zr and Ta sources in 2-methoxy ethanol. The LLZTO pellets made with the prepared powder showed cubic garnet structure for all conditions when the amount of Li addition was varied from 6.2 to 7.4 mol. All the X-ray peaks of the pyrochlore phase disappeared when the Li addition was increased above 7.0 mol. When the final sintering temperature was varied, the LLZTO pellet had a pyrochlore-mixed cubic phase above $1000^{\circ}C$. However, the surface morphology became much denser when the final sintering temperature was increased. The sol-gel-driven LLZTO pellet with a sintering temperature of $1100^{\circ}C$ showed a lithium ionic conductivity of 0.21 mS/cm when Au was adopted as electrode material for the blocking capacitor. The results of this study suggest that modified sol-gel synthesis is the optimum method to obtain cubic phase of LLZTO powder for highly dense and conductive solid electrolyte ceramics.

Keywords

References

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