Thesis or Dissertation Synthesis, structure and ionic conductivity of lithium ion conductors with perovskite and pyrochlore structures

プラーオピパット, タンヤー  ,  PHRAEWPHIPHAT, THANYA

Structures and ionic conductivities of the new perovskite oxides and pyrochlore oxyflurides were investigated. Solid solutions of the new perovskite oxides, (LixSr1-x-y)(Ga[(1-x)/2]-yTa[(1+x)/2]+y)O3, were synthesized using a ball-mill-assisted solid-state reaction with the composition range of 0 ≤ y ≤ 0.20. The highest ionic conductivity was obtained for the composition of x = 0.25 and y = 0.125. Introduction of vacancies at the A-sites, which was determined by neutron diffraction analysis, leads to higher ionic conductivities. Lithium containing pyrochlore oxyflurides, LiSrB2O6F, Li1.1SrB1.9Zr0.1O6F and LiSr0.9B2O6F0.8 with B = Nb+5 and Ta+5, were synthesized by a high-pressure method and their ionic conductivities were clarified. LiSr0.9B2O6F0.8 showed the highest ionic conductivity, which is due to the introduction vacancies at the A- and F-sites. Their structure-property relationships are discussed based on the structure and conductivity data.

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