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

Tomohiro Ishiyama, Takuya Yamaguchi, Junji Nishii, Toshiharu Yamashita, Hiroshi Kawazoe, Naoaki Kuwata, Junichi Kawamura, Takahisa Omata

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

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 31P magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopies. The glass before APS consists of (PO3-)8.6(P2O74-) chains on average and the terminal Q1 units (-O-PO33-) 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(P2O74-) 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. This journal is

Original languageEnglish
Pages (from-to)13640-13646
Number of pages7
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number20
DOIs
Publication statusPublished - 2015 May 28

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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