Major improvement of ferroelectric and optical properties in Na-doped Ruddlesden-Popper layered hybrid improper ferroelectric compound, Ca3Ti2O7

Published

August 20, 2019

Author(s)

Cong Hang, Wei Fang Liu, Winnie Wong-Ng, Ziongnan Zhang, Yao Jiang, Ping Wu, Baoyuan Tong, Hui Zhao, Shouyu Wang

Abstract

Ruddlesden-Popper layered Ca3-xNaxTi2O7 (x=0 and 0.15) ceramics were successfully prepared by a conventional solid-state reaction process. The polarization and leakage currents were increased after Na doping. XPS spectra showed an increasing concentration of oxygen vacancies which played an important role in the transport properties of these samples. Interestingly, a diode-like effect was observed in the Na-doped sample, which is most likely due to a newly formed p-n junction caused by the applied voltage. Optical characterization by UV-visible absorption showed a decrease of band gap from 3.55 to 3.41eV via Na doping. The first-principles calculation showed evidence of a broadening of the conduction band via Na doping, which was caused by the increasing range of unoccupied states in the Ti d orbitals.

Citation

Applied Physics Letters

Volume

770

Pub Type

Journals

Keywords

Ca3-xNaxTi2O7 (x=0 and 0.15), Ruddlesden-Popper pervskites, ferroelectric and optical properties, leakage current

Citation

Hang, C. , Liu, W. , Wong-Ng, W. , Zhang, Z. , Jiang, Y. , Wu, P. , Tong, B. , Zhao, H. and Wang, S. (2019), Major improvement of ferroelectric and optical properties in Na-doped Ruddlesden-Popper layered hybrid improper ferroelectric compound, Ca3Ti2O7, Applied Physics Letters (Accessed October 13, 2025)