Valence Instabilities, Phase Transitions, and Abrupt Lattice Expansion at 5 K in the YbGaGe System

Serena Margadonna, Kosmas Prassides, Andrew N. Fitch, James R. Salvador, Mercouri G. Kanatzidis

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The powder synchrotron X-ray diffraction technique was used to study the thermal expansion behavior of the mixed valence layered compound, YbGa1.05Ge0.95 in the temperature range 3?1123 K. A surprising abrupt isosymmetric phase transition, accompanied by a dramatic volume increase (negative thermal expansion), was found at 5 K induced by a sudden Yb valence transition from +(2 + ε) toward +2. At high temperatures, the material undergoes a transformation to a highly disordered structure until it eventually collapses at 1123 K to a structure with isovalent Yb ions and flat Ga/Ge planes (AlB2 type).

Original languageEnglish
Pages (from-to)4498-4499
Number of pages2
JournalJournal of the American Chemical Society
Volume126
Issue number14
DOIs
Publication statusPublished - Apr 14 2004

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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