Structural and electrochemical properties of hydrogen titanium oxides

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• 作者：Kunimitsu Kataoka ; Norihito Kijima ; Junji Akimoto
• 关键词：Crystal structure ; Neutron diffraction ; Ion-exchange method
• 刊名：Solid State Ionics
• 出版年：1 December, 2013
• 年：2013
• 卷：252
• 期：Complete
• 页码：109-115
• 全文大小：1048 K

文摘

Hydrogen titanium oxide H₂Ti₆O₁₃ was prepared from Li₂Ti₆O₁₃ as a parent compound via Li⁺/H⁺ ion exchange in acidic solution at 60 掳C. It crystallizes in the monoclinic system, space group C2/m, and the lattice parameters of a = 14.6604(3) 脜, b = 3.74109(8) 脜, c = 9.2487(2) 脜, and 尾 = 96.956(2)掳. The crystal structure of H₂Ti₆O₁₃ was refined to the conventional values of R_wp = 3.12% and R_p = 2.45% with a fit indicator of GOF = R_wp / R_e = 1.39 by Rietveld analysis using powder neutron diffraction data. The basic (Ti₆O₁₃)^{2 鈭?/sup> framework in H₂Ti₆O₁₃ was maintained nearly unchanged from that in the parent Li₂Ti₆O₁₃. The hydrogen site in the tunnel space was refined with the strict O3H1 distance of 0.94(1) 脜 in H₂Ti₆O₁₃. The structural stability of H₂Ti₆O₁₃ was confirmed by bond valence sums and 1H-MAS NMR measurement. The total protonic conductivity in H₂Ti₆O₁₃ was estimated to be 蟽_total = 8.32 脳 10鈭?#xA0;6 S cm鈭?#xA0;1 at room temperature from the results of AC-impedance measurements. This value is comparable to that of the well-known good protonic conducting ramsdellite-type H₂Ti₃O₇.}