Li2.5V2(PO4)3: A Room-Temperature Analogue to the Fast-Ion Conducting High-Temperature -
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- 作者：S.-C. Yin ; P. S. Strobel ; H. Grondey ; and L. F. Nazar
- 刊名：Chemistry of Materials
- 出版年：2004
- 出版时间：April 20, 2004
- 年：2004
- 卷：16
- 期：8
- 页码：1456 - 1465
- 全文大小：435K
- 年卷期：v.16,no.8(April 20, 2004)
- ISSN：1520-5002
文摘
The structure of the NASICON-like phase Li2.5V2(PO4)3 has been determined by X-rayand neutron powder diffraction, demonstrating that it crystallizes in the space group P21/n(a = 8.5539(4) Å; b = 8.6099(4) Å; c = 11.9825(5) Å; 
= 90.002(7)
). Combined studies using6,7Li MAS NMR, EPR, and ac impedance spectroscopy show that this pseudo-orthorhombiclattice represents a room-temperature analogue of the high-temperature orthorhombic phase
-Li3Sc2(PO4)3. Lithium disorder over partially vacant sites leads to enhanced ion mobility.EPR spectroscopy confirms the presence of localized V4+ in the lattice, whose short-rangeorder with V3+ gives rise to five resolvable Li shifts in the 6,7Li MAS NMR spectrum. Theseshifts can be rationalized by consideration of the Fermi-contact interactions arising fromthe difference between V3+ and V4+ coupling in the three lithium sites.
= 90.002(7)). Combined studies using6,7Li MAS NMR, EPR, and ac impedance spectroscopy show that this pseudo-orthorhombiclattice represents a room-temperature analogue of the high-temperature orthorhombic phase-Li3Sc2(PO4)3. Lithium disorder over partially vacant sites leads to enhanced ion mobility.EPR spectroscopy confirms the presence of localized V4+ in the lattice, whose short-rangeorder with V3+ gives rise to five resolvable Li shifts in the 6,7Li MAS NMR spectrum. Theseshifts can be rationalized by consideration of the Fermi-contact interactions arising fromthe difference between V3+ and V4+ coupling in the three lithium sites.