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

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/O-2 atmospheres produced a spherical core-shell nanostructure (30-35 nm), with perovskite Eu0.5Ba0.5TiO3 nanocrystal core-insulating oxide shell layer (similar to 3 nm), presumed a pre-pyrochlore layer abundant with Eu3+. Fluorescence spectroscopy shows a high intensity D-5(0) -> F-7(2) 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 G omega mm(-1)) and an extremely stable, low loss permittivity of epsilon(eff) similar to 25 over a wide frequency range (tan delta < 0.01, 100 kHz-2 MHz). Eu0.5Ba0.5TiO3 prepared under H-2/argon produced more irregular shaped nanocrystals (20-25) nm, with a thin film permittivity around 4 times greater (epsilon(eff) 101, tan delta < 0.05, 10 kHz-2 MHz, sigma similar to 59.54 k omega 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 Eu-II/III/Ti-III/IV configurations which contribute to the observed ferroic and fluorescence behavior.

Automated summary

Nanoscale Eu0.5Ba0.5TiO3 is a multiferroic material with potential applications in quantifying electric dipole moment of electron, nanocomposite integration, biomedical imaging, and fundamental research. Different properties of Ba:Ti:Eu nanocompounds can be obtained by altering oxidizing/reducing conditions.