Multifunctional properties of Ho3+/Yb3+ Co-doped BaBi2Nb2O9 relaxor ferroelectric ceramics

Abstract

Ho³⁺/Yb³⁺ co-doped relaxor ferroelectric ceramic BaBi_2-0.04-yNb₂Ho_0.04Yb_yO₉ were prepared by solid state method at optimized calcination and sintering temperature and studied for their structural, luminescent, ferroelectric and dielectric properties. A single-phase orthorhombic crystal structure with the F_mmm space group was confirmed by high-resolution X-ray diffraction analysis. SEM micrographs exhibited dense truncated microplate like structures with average grain size in line with diffraction studies. Doped ceramics showed excellent luminescent and upconversion luminescent properties. After rare earth ions incorporation in the host lattice, luminescence spectra revealed two prominent emission bands at 550 nm and 665 nm upon 980 nm excitation wavelength. The dominating FTIR bands were observed at 621 cm⁻¹ and 823 cm⁻¹ due to NbO₆ bond vibration. The UV-Vis Spectroscopy showed the change in bandgap with the substitution of rare earth ions in doped ceramics. The dielectric constant (ε′) falls as frequency increased, and dielectric behavior measured with temperature showed a notable dispersion below and above temperature (T_m). The relaxor behavior of all the synthesized BBN compositions was confirmed by the dielectric loss (ε′) curves, which were very diffused and exhibit shifts in maxima with frequency. The narrower PE curves were achieved within the optimized range of electric field and energy storage parameters were evaluated across different electric fields with varying dopants.