High Oxide Ion Conductivity in Al-Doped Germanium Oxyapatite
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- 作者：Laura Leó ; n-Reina ; Enrique R. Losilla ; Marí ; a Martí ; nez-Lara ; M. Carmen Martí ; n-Sedeñ ; o ; Sebastiá ; n Bruque ; Pedro Nú ; ñ ; ez ; Denis V. Sheptyakov ; and Migu
- 刊名：Chemistry of Materials
- 出版年：2005
- 出版时间：February 8, 2005
- 年：2005
- 卷：17
- 期：3
- 页码：596 - 600
- 全文大小：86K
- 年卷期：v.17,no.3(February 8, 2005)
- ISSN：1520-5002
文摘
The apatite La10-x
ntities/square.gif">x(Ge5.5Al0.5O24)O2.75-1.5x (10 - x = 9.80, 9.75, 9.67, 9.60, 9.50, and 9.40) serieshas been prepared and the single phase existence range has been established, 9.75 ntities/ge.gif"> 10 - x ntities/ge.gif"> 9.45. Thehexagonal crystal structures of La9.5ntities/square.gif">0.5(Ge5.5Al0.5O24)O2 have been determined at room temperature,500 ntities/deg.gif">C, and 900 ntities/deg.gif">C from neutron powder diffraction data using the Rietveld method. The room-temperatureunit cell parameters were a = 9.9206(4) Å, c = 7.2893(3) Å, V = 621.29(6) Å3, and Z = 1, and thisrefinement converged to RWP = 3.03 and RF = 1.30%. The most important structural result is the presenceof interstitial oxygen ion associated with vacancies at the apatite oxide anions channels. Oxide ionconductivities have been measured by impedance spectroscopy. La9.5ntities/square.gif">0.5(Ge5.5Al0.5O24)O2 shows veryhigh oxide conductivity, 0.16(1) S·cm-1 at 800 ntities/deg.gif">C, with negligible electronic contribution. The ionictransport number, obtained by combination of impedance and ion-blocking data, is higher than 0.99 inthe studied oxygen partial pressure range, 0.21 to 10-20 atm.
ntities/square.gif">x(Ge5.5Al0.5O24)O2.75-1.5x (10 - x = 9.80, 9.75, 9.67, 9.60, 9.50, and 9.40) serieshas been prepared and the single phase existence range has been established, 9.75 ntities/ge.gif"> 10 - x ntities/ge.gif"> 9.45. Thehexagonal crystal structures of La9.5ntities/square.gif">0.5(Ge5.5Al0.5O24)O2 have been determined at room temperature,500 ntities/deg.gif">C, and 900 ntities/deg.gif">C from neutron powder diffraction data using the Rietveld method. The room-temperatureunit cell parameters were a = 9.9206(4) Å, c = 7.2893(3) Å, V = 621.29(6) Å3, and Z = 1, and thisrefinement converged to RWP = 3.03 and RF = 1.30%. The most important structural result is the presenceof interstitial oxygen ion associated with vacancies at the apatite oxide anions channels. Oxide ionconductivities have been measured by impedance spectroscopy. La9.5ntities/square.gif">0.5(Ge5.5Al0.5O24)O2 shows veryhigh oxide conductivity, 0.16(1) S·cm-1 at 800 ntities/deg.gif">C, with negligible electronic contribution. The ionictransport number, obtained by combination of impedance and ion-blocking data, is higher than 0.99 inthe studied oxygen partial pressure range, 0.21 to 10-20 atm.