ChemInform Abstract: Soft-Chemistry of Garnet-Type Li5+xBaxLa3-xNb2O12 (x = 0, 0.5, 1): Reversible H+↔Li+ Ion-Exchange Reaction and Their X-Ray, Li MAS NMR, IR, and AC Impedance Spectroscopy Characterization.
✍ Scribed by Lina Truong; Venkataraman Thangadurai
- Publisher
- John Wiley and Sons
- Year
- 2011
- Weight
- 24 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0931-7597
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✦ Synopsis
Soft-Chemistry of Garnet-Type Li 5+x Ba x La 3-x Nb 2 O 12 (x = 0, 0.5, 1): Reversible H + ↔Li + Ion-Exchange Reaction and Their X-Ray, Li MAS NMR, IR, and AC Impedance Spectroscopy Characterization. -The title compounds are prepared by a ceramic method from stoichiometric mixtures of LiNO3, Ba(NO3)2, La2O3, and Nb2O3 (alumina crucible, 700 °C for 24 h and sintering at 950 °C for 24 h in air). The H + /Li + exchange of the samples is characterized by powder XRD, FTIR, SEM, 7 Li MAS NMR, and electrochemical ac impedance spectroscopy. The H + /Li + exchange in water at room temperature is most successful for x = 0, with about 89% exchange, while for x = 0.5 and x = 1 only about 46% and about 20% exchange occurs, respectively. In Li5La3Nb2O12, about 80% of the Li ions occupy tetrahedral sites. The population of the octahedral Li sites increases with increasing Li content of the title compounds. It is concluded that Li ions at the tetrahedral sites favor facile H + /Li + exchange, while octahedral-site ions are rather stable against proton exchange in water at 23 °C. The reversible nature of the ion exchange process is demonstrated by similar electrical properties of reverse-ion-exchanged and as-prepared Li5La3Nb2O12. -(TRUONG, L.;