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

doi:10.1021/ja049728w

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

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

The powder synchrotron X-ray diffraction technique was used to study the thermal expansion behavior of the mixed valence layered compound, YbGa_1.05Ge_0.95 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 language	English (US)
Pages (from-to)	4498-4499
Number of pages	2
Journal	Journal of the American Chemical Society
Volume	126
Issue number	14
DOIs	https://doi.org/10.1021/ja049728w
State	Published - Apr 14 2004

ASJC Scopus subject areas

Catalysis
Chemistry(all)
Biochemistry
Colloid and Surface Chemistry

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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).",

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AU - Margadonna, Serena

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AU - Salvador, James R.

AU - Kanatzidis, Mercouri G.

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AB - 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).

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