Correlation of formation enthalpies with critical amorphization temperature for pyrochlore and monazite

K. B. Helean, A. Navrotsky, J. Lian, R. C. Ewing

Research output: Contribution to journalConference articlepeer-review

7 Scopus citations

Abstract

Systematic studies of a series of RE-titanate pyrochlore single crystals determined the formation enthalpies, ΔH0f-ox, and the critical amorphization temperature, Tc, the temperature above which the crystal can no longer be amorphized. A negative linear correlation was observed between ΔH0f-ox and Tc. In general as the cation radius ratio, RA/RB, decreases the formation enthalpy becomes less exothermic, i.e. the pyrochlore structure becomes less thermodynamically stable while the susceptibilty to ion beam-induced amorphization decreases. The opposite relation, i.e. a positive linear correlation between ΔH0f-ox and Tc was observed for a series of REPO4 single crystals with both the monazite and xenotime structures. Both relations can be understood in terms of pyrochlore and orthophosphate crystal chemistry, their formation of point defects, and the role of ion-irradiation induced phase transformations.

Original languageEnglish (US)
Article numberCC4.7
Pages (from-to)279-285
Number of pages7
JournalMaterials Research Society Symposium Proceedings
Volume824
DOIs
StatePublished - 2004
Externally publishedYes
EventScientific Basis for Nuclear Waste Management XXVIII - San Francisco, CA, United States
Duration: Apr 13 2004Apr 16 2004

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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