Anion ordered and ferroelectric ruddlesden-popper oxynitride Ca3Nb2N2O5 for visible-light-active photocatalysis

Gaoyang Gou*, Min Zhao, Jing Shi, Jaye K. Harada, James M. Rondinelli

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

A new ferroelectric perovskite oxynitride is proposed and demonstrated for photocatalytic applications using a systematic first-principles study. Ruddlesden-Popper (RP) Ca3Nb2N2O5, a layered structural derivative of the parent nonpolar perovskite CaNbO2N, can exhibit a-a-c+ octahedral-rotation-induced ferroelectricity due to hybrid improper ferroelectricity. We use first-principles calculations to reveal that RP Ca3Nb2N2O5 exhibits a sizable ferroelectric polarization up to 25 μC/cm2 along the in-plane crystallographic direction. As a-a-c+ octahedral rotations are pervasive within the Ca3Nb2N2O5 lattice, rotation-induced ferroelectricity is weakly dependent on the anion arrangement and nearly homogeneous throughout the entire configuration space. Furthermore, our electronic structure calculations indicate that ferroelectric Ca3Nb2N2O5 exhibits a direct band gap of 2.15 eV, strong visible light absorbance up to 580 nm, and dispersive energy bands along the in-plane directions. The spectrally suitable band gap and spontaneous ferroelectric polarization, benefiting the separation of photoexcited electron-hole pairs, enable Ca3Nb2N2O5 to display promising photocatalytic performance over the visible spectrum. Finally, we demonstrate the prevalence of planar cis-type O/N arrangements in Ca3Nb2N2O5: the apical anion sites are fully occupied by O and equatorial sites have 1:1 O/N mixed occupancy. Such a robust 1 O/ 2(O0.5N0.5) partial anion order should be detectable using standard experimental measurements, making RP Ca3Nb2N2O5 a unique perovskite oxynitride to investigate the interplay among ferroelectricity, octahedral rotations, and O/N anion order.

Original languageEnglish (US)
Pages (from-to)2815-2823
Number of pages9
JournalChemistry of Materials
Volume32
Issue number7
DOIs
StatePublished - 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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