| NASICON 고체 전해질의 이온 전도도 계산 (II) Na1-Na2 전도 경로에 미치는 mid-Na의 영향 |
| 최진삼, 서양곤1, 강은태 |
경상대학교 무기재료공학과
1경상대학교 화학공학과 |
| Computation of Ionic Conductivity at NASICON Solid Electrolytes (II) Effects of mid-Na Sites on Na1-Na2 Conduction Paths |
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| ABSTRACT |
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The ionic conductivity of NASICON solid electrolytes was simulated by using Monte Carlo Method (MCM). There were included two conduction paths: (1) Na1-Na2 and (2) Na1-Na2 including Na2-Na2. We assumed that mid-Na ions provde an additional driving force for Na mobile ions due to the interionic repulsion between Na1 and Na2 ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, W increased rapidly with the composition at low temperature, but decreased at high temperature region. On Na1-Na2 conduction path, the minimum of charge correlation factor, fc and the maximum of $sigma$T were appeared at x=2.0. this indicated that mid-Na ions affect on the high ionic conductivity behavior. At the whole range of NASICON composition, 1n $sigma$T vs. 1/T* plots have been shown Arrhenius behavior but 1n (VWFc) vs. 1/T* have been shown the Arrhenius type tendency at x=2, which mid-Na is being the maximum. The results of MCM agreed with the experimental one when the chosen saddle point value was 6$varepsilon$ : 3$varepsilon$. Here the calculated characteristic parameter of materials, K and the phase transition temperature were -4.001$times$103 and 178$^{circ}C$ (1/T*=1.92, 1000/T=2.22), respectively. |
| Key words:
Mid-Na, Repulsion between Na ions, Na1-Na2 conduction path, Arrhenius plot, NASICON ionic conductivity |
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