Structural change of NaO1/2-WO3-NbO5/2-LaO3/2-PO5/2 glass induced by electrochemical substitution of sodium ions with protons.

Structural changes of 35NaO1/2-1WO3-8NbO5/2-5LaO3/2-51PO5/2 glass (1W-glass) before and after the electrochemical substitution of sodium ions with protons by alkali-proton substitution (APS) are studied by Raman and (31)P magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopies. The glass before APS consists of (PO3(-))8.6(P2O7(4-)) chains on average and the terminal Q(1) units (-O-PO3(3-)) are bound to MO6 octahedra (M denotes niobium or tungsten) through P-O-M bonds. Some non-bridging oxygens (NBOs) in the MO6 octahedra are present in addition to the bridging oxygens (BOs) in P-O-M bonds. APS induces fragmentation of the phosphate chains because the average chain length decreases to (PO3(-))3.7(P2O7(4-)) after APS, despite the total number of modifier cations of sodium and lanthanum ions and protons being unaffected by APS. This fragmentation is induced by some of the NBOs in the MO6 octahedra before APS, changing to BOs of the newly formed M-O-P bonds after APS, because of the preferential formation of P-OH bonds over M-OH ones in the present glass. We show that APS under the conditions used here is not a simple substitution of sodium ions with protons, but it is accompanied by the structural relaxation of the glass to stabilize the injected protons.

[1]  J. Nishii,et al.  Improving thermal stability and its effects on proton mobility in proton-conducting phosphate glasses prepared by the electrochemical substitution of sodium ions with protons , 2015 .

[2]  J. Nishii,et al.  Proton conducting tungsten phosphate glass and its application in intermediate temperature fuel cells , 2014 .

[3]  J. Nishii,et al.  Electrochemical substitution of sodium ions with protons in phosphate glass to fabricate pure proton conducting glass at intermediate temperatures , 2014 .

[4]  Lei Bi,et al.  Towards the Next Generation of Solid Oxide Fuel Cells Operating Below 600 °C with Chemically Stable Proton‐Conducting Electrolytes , 2012, Advanced materials.

[5]  E. Wachsman,et al.  Lowering the Temperature of Solid Oxide Fuel Cells , 2011, Science.

[6]  G. Righini,et al.  Raman optical amplification properties of sodium–niobium–phosphate glasses , 2010 .

[7]  Emiliana Fabbri,et al.  Materials challenges toward proton-conducting oxide fuel cells: a critical review. , 2010, Chemical Society reviews.

[8]  D. Brett,et al.  Intermediate temperature solid oxide fuel cells. , 2008, Chemical Society reviews.

[9]  Steve W. Martin,et al.  The comparative structure, properties, and ionic conductivity of LiI + Li2S + GeS2 glasses doped with Ga2S3 and La2S3 , 2008 .

[10]  S. Ribeiro,et al.  Structural studies of NaPO3–WO3 glasses by solid state NMR and Raman spectroscopy , 2006 .

[11]  A. Kuhn,et al.  New protonic solid electrolyte with tetragonal tungsten bronze structure obtained through ionic exchange , 2004 .

[12]  S. Haile,et al.  High-Temperature Behavior of CsH2PO4 under Both Ambient and High Pressure Conditions , 2003 .

[13]  G. Hoatson,et al.  Modelling one‐ and two‐dimensional solid‐state NMR spectra , 2002 .

[14]  B. Zhu.  Advantages of intermediate temperature solid oxide fuel cells for tractionary applications , 2001 .

[15]  S. Chung,et al.  Mass transport of phosphoric acid in water: A 1H and 31P pulsed gradient spin-echo nuclear magnetic resonance study , 2000 .

[16]  Richard K. Brow,et al.  Review: the structure of simple phosphate glasses , 2000 .

[17]  T. Norby.  Solid-state protonic conductors: principles, properties, progress and prospects , 1999 .

[18]  James F. Babb,et al.  HIGH-PRECISION CALCULATIONS OF DISPERSION COEFFICIENTS, STATIC DIPOLE POLARIZABILITIES, AND ATOM-WALL INTERACTION CONSTANTS FOR ALKALI-METAL ATOMS , 1998, physics/9812028.

[19]  J.P.P. Huijsmans,et al.  Intermediate temperature SOFC – a promise for the 21st century , 1998 .

[20]  R. Kirkpatrick,et al.  Nuclear magnetic resonance investigation of the structures of phosphate and phosphate-containing glasses: a review. , 1995, Solid state nuclear magnetic resonance.

[21]  Steve W. Martin,et al.  The short-range structure of sodium ultraphosphate glasses , 1994 .

[22]  Mártin,et al.  Correlation functions for ionic motion from NMR relaxation and electrical conductivity in the glassy fast-ion conductor (Li2S)0.56(SiS2)0.44. , 1993, Physical review. B, Condensed matter.

[23]  K. Hayamizu,et al.  Spinning-rate dependence of 31P magic-angle-spinning nuclear magnetic resonance spectra in condensed phosphates , 1991 .

[24]  G. Farrington,et al.  Protonic solid electrolytes: thermal stability and conductivity of ammonium/hydronium β″-alumina , 1989 .

[25]  Goldman Sp.  Gauge-invariance method for accurate atomic-physics calculations: Application to relativistic polarizabilities. , 1989 .

[26]  S. Sakka,et al.  Coordination state of Nb5+ ions in silicate and gallate glasses as studied by Raman spectroscopy , 1988 .

[27]  P. Hagenmuller,et al.  Structural investigation of glasses belonging to the Na2ONb2O5P2O5 system , 1988 .

[28]  H. Iwahara,et al.  Proton Conduction in Sintered Oxides Based on BaCeO3 , 1988 .

[29]  S. Prabhakar,et al.  A magic-angle spinning 31P NMR investigation of crystalline and glassy inorganic phosphates , 1987 .

[30]  Larry L. Hench,et al.  Protonic conduction in alkaline earth metaphosphate glasses containing water , 1982 .

[31]  M. Breiter,et al.  Ionic conductivity in H3O+ beta alumina , 1978 .

[32]  R. Irani,et al.  Phosphorus Nuclear Magnetic Resonance Studies of Ortho and Condensed Phosphates , 1962 .

[33]  J. Nishii,et al.  Electrochemical Substitution of Sodium Ions in Tungsten Phosphate Glass with Protons , 2013 .

[34]  Zongqiang Mao,et al.  Development of solid oxide fuel cell materials for intermediate-to-low temperature operation , 2012 .

[35]  P. Vinatier,et al.  Aggregation of the doping salt in B2S3–Li2S–LiI glasses, effect on the dynamical properties , 1999 .

[36]  M. Nogami,et al.  Superprotonic Conductors of Glassy Zirconium Phosphates , 1996 .

[37]  J. Jehng,et al.  Structural chemistry and Raman spectra of niobium oxides , 1991 .

[38]  S. Risbud,et al.  Raman spectroscopy of calcium phosphate glasses with varying calcium oxide modifier concentrations , 1991 .

[39]  T. Minami,et al.  Structure of rapidly quenched lithium phosphate glasses , 1988 .