Sodium Mobility in the NASICON Series Na1+xZr2-xInx(PO4)3
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- 作者：Enrique R. Losilla ; Miguel A. G. Aranda ; Sebastiá ; n Bruque ; Jesú ; s Sanz ; Miguel A. Parí ; s ; Javier Campo ; and Anthony R. West
- 刊名：Chemistry of Materials
- 出版年：2000
- 出版时间：August 2000
- 年：2000
- 卷：12
- 期：8
- 页码：2134 - 2142
- 全文大小：282K
- 年卷期：v.12,no.8(August 2000)
- ISSN：1520-5002
文摘
Rhombohedral Na1+xZr2-xInx(PO4)3 (x = 0, 0.2, 0.4, 0.8, 1.0, 1.2, 1.6, and 1.8) NASICONmaterials have been studied by XRPD, variable-temperature NPD, 31P and variable-temperature 23Na MAS NMR, and impedance spectroscopies. Relative 31P MAS NMR peakintensities of the five detected signals, attributed to the environments [P(OZr)4-n(OIn)n (n= 0-4)], are close to those expected for a random distribution of octahedral cations. Thislocal probe allows us to rule out the existence of segregated metal-rich nanoregions. CombinedNPD and XRPD Rietveld studies showed that the occupation of M2 sites by the extra Na+cations produces a slight distortion of the structure. Low temperatures freeze Na mobilitiesand permit the assignment of the resulting NMR bands to Na+ in the M1 and M2 sites. Themobility of Na at room temperature increases with the Na content. For samples with x <0.8, Na ions are relatively localized; however, for x 
ntities/ge.gif"> 0.8, Na mobility increases, yielding aunique signal in the 23Na NMR spectra. The increase of Na mobility causes spatial disorderat the M1 site as deduced from the variable-temperature NPD study. At low temperatures,the activation energies do not change significantly. So, the observed increase in bulkconductivity by 2 orders of magnitude in the low-temperature regime is ascribed to anincrease of mobile carrier, Na+, concentration. However, at higher temperatures a new regimehas been identified by NPD, 23Na MAS NMR, and Arrhenius plots of fmax data in Z' ' spectraand is associated with more extended sodium motion. The onset temperature for thecurvature in the Z' ' fmax Arrhenius plots, when reaching the high-temperature regime,depends on sodium content.
ntities/ge.gif"> 0.8, Na mobility increases, yielding aunique signal in the 23Na NMR spectra. The increase of Na mobility causes spatial disorderat the M1 site as deduced from the variable-temperature NPD study. At low temperatures,the activation energies do not change significantly. So, the observed increase in bulkconductivity by 2 orders of magnitude in the low-temperature regime is ascribed to anincrease of mobile carrier, Na+, concentration. However, at higher temperatures a new regimehas been identified by NPD, 23Na MAS NMR, and Arrhenius plots of fmax data in Z' ' spectraand is associated with more extended sodium motion. The onset temperature for thecurvature in the Z' ' fmax Arrhenius plots, when reaching the high-temperature regime,depends on sodium content.