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 language | English |
|---|---|
| Pages (from-to) | 131-139 |
| Number of pages | 9 |
| Journal | Crystal Growth and Design |
| Volume | 14 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 2 2014 |
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ASJC Scopus subject areas
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics
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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 journal › Article
}
TY - JOUR
T1 - Competing cation-anion interactions and noncentrosymmetry in metal oxide-fluorides
T2 - A first-principles theoretical study
AU - Mishra, Abhishek Kumar
AU - Marvel, Michael R.
AU - Poeppelmeier, Kenneth R
AU - Waghmare, Umesh V.
PY - 2014/1/2
Y1 - 2014/1/2
N2 - 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.
AB - 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.
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U2 - 10.1021/cg401296f
DO - 10.1021/cg401296f
M3 - Article
VL - 14
SP - 131
EP - 139
JO - Crystal Growth and Design
JF - Crystal Growth and Design
SN - 1528-7483
IS - 1
ER -