Symmetric Stretching Vibrations of Two-Coordinate Oxygen Bridges as a Cause for Negative Thermal Expansion in ZrV x P 2-x O 7 andAW 2 O 8 (A=Zr, Hf) at High Temperature

Dong Kyun Seo, Myung Hwan Whangbo

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Abstract

To examine the origin of negative thermal expansion in oxides ZrV x P 2-x O 7 (x=0-2) andAW 2 O 8 (A=Zr, Hf),ab initioself-consistent-field molecular orbital calculations were carried out for a model compound (HO) 3 P-O-P(OH) 2+ 3 . Our study suggests that symmetric stretching vibrations of two-coordinate oxygen bridges are strongly coupled with their bending vibrations and are more important for negative thermal expansion at high temperature. The oxygen bridges accomodate a large stretching of theA-O (A=Zr, Hf) andM-O (M=P,V) bonds at high temperature by decreasing the bond angles of the oxygen bridges. When the bond angles increase, the bonds are shortened due to the π-type orbital interactions associated with the oxygen lone pair orbitals.

Original languageEnglish
Pages (from-to)160-163
Number of pages4
JournalJournal of Solid State Chemistry
Volume129
Issue number1
DOIs
Publication statusPublished - Feb 15 1997

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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