Enthalpies of formation of rare earth niobates, RE3NbO7

Aleksandra Mielewczyk-Gryn, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

High-temperature oxide melt solution calorimetry was used to investigate energetics of a series of rare earth niobates RE3NbO7. All of investigated compounds were found to be stable in enthalpy in respect to their oxides. The enthalpy of formation from oxides becomes more exothermic as the size of the RE cation increases, a trend seen previously in other RE compounds including pyrochlores, perovskites, and phosphates. For smaller RE cations the enthalpy of exchange of RE between niobates and titanates is close to zero, whereas larger RE are energetically favored in the titanate pyrochlores. Implications of the results from the geochemical and material engineering points of view are discussed.

Original languageEnglish (US)
Pages (from-to)1578-1583
Number of pages6
JournalAmerican Mineralogist
Volume100
Issue number7
DOIs
StatePublished - Jul 1 2015
Externally publishedYes

Keywords

  • defect fluorite
  • heat of formation
  • Niobates
  • oxide melt solution calorimetry
  • pyrochlore
  • rare earth minerals

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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