Issue 23, 2021

Magnetic and dielectric property control in the multivalent nanoscale perovskite Eu0.5Ba0.5TiO3

Abstract

We report nanoscale Eu0.5Ba0.5TiO3, a multiferroic in the bulk and candidate in the search to quantify the electric dipole moment of the electron. Eu0.5Ba0.5TiO3, in the form of nanoparticles and other nanostructures is interesting for nanocomposite integration, biomedical imaging and fundamental research, based upon the prospect of polarizability, f-orbital magnetism and tunable optical/radio luminescence. We developed a [non-hydrolytic]sol–[H2O-activated]gel route, derived from in-house metallic Ba(s)/Eu(s) alkoxide precursors and Ti{(OCH(CH3)2}4. Two distinct nanoscale compounds of Ba:Ti:Eu with the parent perovskite crystal structure were produced, with variable dielectric, magnetic and optical properties, based on altering the oxidizing/reducing conditions. Eu0.5Ba0.5TiO3 prepared under air/O2 atmospheres produced a spherical core–shell nanostructure (30–35 nm), with perovskite Eu0.5Ba0.5TiO3 nanocrystal core-insulating oxide shell layer (∼3 nm), presumed a pre-pyrochlore layer abundant with Eu3+. Fluorescence spectroscopy shows a high intensity 5D07F2 transition at 622 nm and strong red fluorescence. The core/shell structure demonstrated excellent capacitive properties: assembly into dielectric thin films gave low conductivity (2133 GΩ mm−1) and an extremely stable, low loss permittivity of εeff ∼25 over a wide frequency range (tan δ < 0.01, 100 kHz–2 MHz). Eu0.5Ba0.5TiO3 prepared under H2/argon produced more irregular shaped nanocrystals (20–25) nm, with a thin film permittivity around 4 times greater (εeff 101, tan δ < 0.05, 10 kHz–2 MHz, σ ∼59.54 kΩ mm−1). Field-cooled magnetization values of 0.025 emu g−1 for EBTO-Air and 0.84 emu g−1 for EBTO-Argon were observed. X-ray photoelectron spectroscopy analysis reveals a complex interplay of EuII/III/TiIII/IV configurations which contribute to the observed ferroic and fluorescence behavior.

Graphical abstract: Magnetic and dielectric property control in the multivalent nanoscale perovskite Eu0.5Ba0.5TiO3

Supplementary files

Article information

Article type
Paper
Submitted
28 Jan 2021
Accepted
05 May 2021
First published
06 May 2021

Nanoscale, 2021,13, 10365-10384

Author version available

Magnetic and dielectric property control in the multivalent nanoscale perovskite Eu0.5Ba0.5TiO3

N. Farahmand, C. K. McGinn, Q. Zhang, Z. Gai, I. Kymissis and S. O'Brien, Nanoscale, 2021, 13, 10365 DOI: 10.1039/D1NR00588J

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