Thermochemistry of phosphorus oxynitrides: PON and LiNaPON glasses

Franck Tessier, Alexandra Navrotsky, André Le Sauze, Roger Marchand

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


High-temperature solution calorimetry has been very useful in elucidating the energetics of many oxide materials Recently, a sodium molybdate melt, 3Na2O·4MoO3, has been shown to be very effective for nitride calorimetry. This methodology has now been used to determine the energetics of formation of phosphorus oxynitride PON samples and of a series of LiNaPON oxynitride glasses. Enthalpies of formation from the elements at 298 K are -371.71 ± 4.45 and -356.14 ± 3.98 kJ mol-1 for β-cristobalite and amorphous PON, respectively, and -961.88 ± 3.86 kJ mol-1 for a 9 wt % nitrogen-containing LiNaPON glass. The β-cristobalite energy of amorphization is -15.57 ± 5.97 kJ mol-1. A linear relation, ΔH(f)/(o)(Li0.5Na0.5PO((3-3x/2))N(x)) = ΔH(f)/(o)(Li0.5Na0.5PO3) + 441.7x, was found between the enthalpies of formation of the glasses and their atomic nitrogen content, x (0 ≤ x ≤ 0.57). The magnitude of the energetics of nitrogen/oxygen substitution within PON and LiNaPON glasses has been correctly evaluated by using N-N, O-O, P-N, and P-O bond strengths. The in-situ precipitation of metallic particles from corresponding oxides in LiNaPON glasses has been predicted from high-temperature solution calorimetry results and appropriate thermodynamic cycles. These results constitute the first set of energetic data on nitridophosphates.

Original languageEnglish (US)
Pages (from-to)148-154
Number of pages7
JournalChemistry of Materials
Issue number1
StatePublished - 2000
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


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