Lanthanum phosphate calcium aluminate glasses: 27Al and 31P NMR spectroscopy

R. Marzke, S. Boucher, George Wolf, J. Piwowarczyk, William Petuskey

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

A new protocol for synthesis of glassy aluminates with substantial content of the refractory compound LaPO4 has been developed, utilizing hydrated monazite and anhydrous metal oxides as starting materials. Ultra high-temperature NMR of samples containing up to 75 mol% LaPO4 shows that monazite is incorporated homogeneously into melts, while analysis by electron microprobe, X-ray diffraction, solid-state NMR and Raman scattering shows that water quench of samples with 50% La-monazite or less results primarily in glass formation. Network structures of the LaPO4-containing glasses remain aluminate-based, as indicated by our samples' melting points (>1200 °C), well above those of phosphate glasses. Melting temperatures exhibit a minimum in the range 20-30% LaPO4 content. Raman spectra show only isolated phosphate groups, with no P{single bond}O{single bond}P bonds (orthophosphates). Dissolution observations, electron microprobe composition measurements and a substantially shifted principal 31P NMR line show that La3+ lies within the second coordination shell around P in all of the glasses. P-Al TRAPDOR NMR studies and a second, more negatively shifted line in the 31P spectra indicate that P is also closely coordinated to one or two Al ions.

Original languageEnglish (US)
Pages (from-to)2421-2431
Number of pages11
JournalJournal of the European Ceramic Society
Volume28
Issue number12
DOIs
StatePublished - Aug 1 2008

Keywords

  • AlO
  • Glass
  • NMR
  • Spectroscopy
  • Thermal properties

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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