Competing cation-anion interactions and noncentrosymmetry in metal oxide-fluorides

A first-principles theoretical study

Abhishek Kumar Mishra, Michael R. Marvel, Kenneth R Poeppelmeier, Umesh V. Waghmare

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Anomalous Born dynamical charges in perovskite oxides, such as BaTiO 3 and KNbO3, are known to be indicators of their tendency to turn polar through cation off-centering and measure of the interaction between d states of transition metal and p states of oxygen. Here, we use first-principles density functional theory based calculations to determine Born charges of noncentrosymmetric KNaNbOF5 and centrosymmetric CsNaNbOF5 with a goal to assess the cation-anion interactions relevant to the breaking of their centrosymmetry. We find that while noncentrosymmetry is favored by the primary Nb-O interaction, covalency in the competing interaction of Cs with anions suppresses it stabilizing the centrosymmetric structure and is reflected clearly in the deviation of Born effective charges (BECs) from their nominal ionic values. We identify specific features in the electronic structure that correlate with stability of the centrosymmetric structure and show that polarization of the noncentrosymmetric KNaNbOF5 estimated using the Berry phase method is rather weak ∼0.21 μC/cm2, consistent with the finding that it originates from the competition between the primary and secondary electronic distortions.

Original languageEnglish
Pages (from-to)131-139
Number of pages9
JournalCrystal Growth and Design
Volume14
Issue number1
DOIs
Publication statusPublished - Jan 2 2014

Fingerprint

Fluorides
Oxides
Anions
metal oxides
fluorides
Cations
Negative ions
Positive ions
Metals
anions
cations
Perovskite
Electronic structure
Transition metals
Density functional theory
interactions
Polarization
Oxygen
tendencies
transition metals

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Competing cation-anion interactions and noncentrosymmetry in metal oxide-fluorides : A first-principles theoretical study. / Mishra, Abhishek Kumar; Marvel, Michael R.; Poeppelmeier, Kenneth R; Waghmare, Umesh V.

In: Crystal Growth and Design, Vol. 14, No. 1, 02.01.2014, p. 131-139.

Research output: Contribution to journalArticle

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