Structural and Electrochemical Studies of Rhombohedral Na2TiM(PO4)3 and Li1.6Na0.4TiM(PO4)3 (M = Fe, Cr) Phosphates
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- 作者：Sé ; bastien Patoux ; Gwenaë ; lle Rousse ; Jean-Bernard Leriche ; and Christian Masquelier
- 刊名：Chemistry of Materials
- 出版年：2003
- 出版时间：May 20, 2003
- 年：2003
- 卷：15
- 期：10
- 页码：2084 - 2093
- 全文大小：347K
- 年卷期：v.15,no.10(May 20, 2003)
- ISSN：1520-5002
文摘
The crystal structures of NASICON compositions Z2TiM(PO4)3 (Z = Na, Li; M = Cr, Fe)were investigated through powder neutron diffraction on the beam lines D1A (
= 1.9104Å) and D2B ( = 1.5924 Å) at ILL, Grenoble, France. Na2TiCr(PO4)3 and Na2TiFe(PO4)3 areisostructural. They crystallize in the space group R
c, with the sodium ions being located inthe M1 (
~ 1) and M2 sites ( ~ 1/3). NASICON Li1.6Na0.4TiCr(PO4)3 and Li1.6Na0.4TiFe(PO4)3 were prepared through ion exchange from the sodium analogues. They crystallize inthe space group R, with the lithium ions being located in the M3 tetrahedral site. Theremaining, unexchanged, sodium ions are still located on the M1 site. Electrochemicalinsertion of sodium or lithium into these structures was followed through slow intermittenttitration techniques coupled with in situ X-ray diffraction. We show that for bothNa2+xTiM(PO4)3 and Li1.6+xNa0.4TiM(PO4)3 (0 
x 1 for M = Cr, 0 x 2 for M = Fe), theinsertion proceeds through a single-phase mechanism.
= 1.9104Å) and D2B ( = 1.5924 Å) at ILL, Grenoble, France. Na2TiCr(PO4)3 and Na2TiFe(PO4)3 areisostructural. They crystallize in the space group Rc, with the sodium ions being located inthe M1 ( ~ 1) and M2 sites ( ~ 1/3). NASICON Li1.6Na0.4TiCr(PO4)3 and Li1.6Na0.4TiFe(PO4)3 were prepared through ion exchange from the sodium analogues. They crystallize inthe space group R, with the lithium ions being located in the M3 tetrahedral site. Theremaining, unexchanged, sodium ions are still located on the M1 site. Electrochemicalinsertion of sodium or lithium into these structures was followed through slow intermittenttitration techniques coupled with in situ X-ray diffraction. We show that for bothNa2+xTiM(PO4)3 and Li1.6+xNa0.4TiM(PO4)3 (0 x 1 for M = Cr, 0 x 2 for M = Fe), theinsertion proceeds through a single-phase mechanism.