Structure and Dielectric Behavior of Yb2O3-MgO Co-Doped 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3 Ferroelectric Relaxor

Dielectric properties and structure of 0.015Yb(2)O(3)-xMgO doped 0.92BaTiO(3)-0.08(Na0.5Bi0.5)TiO3 ceramics with x = 0.0-0.025 have been investigated. As Yb2O3-MgO was added into the BT-NBT, the phase changes from tetragonal to pseudo-cubic, with the tetragonality c/a decreases from 1.011 to 1.008 and XRD peaks broadened. The combined study of XRD and TEM image revealed a formation of core-shell structure in grains with core of 400-600 nm and the shell of a thickness 60-200 nm. There is a slowly phase transition against temperature from the variable temperature Raman analysis. The ferroelectric relaxor peak of BT-NBT decreases from ~4000 to ~2000 and a new broad dielectric peak with an equivalent maximum (epsilon(r)& PRIME;~2300) appears in the temperature dependent dielectric constant curve (epsilon(r)& PRIME;-T), which produces a flat epsilon(r)& PRIME;-T curve. Sample 0.92BaTiO(3)-0.08(Na0.5Bi0.5)TiO3-0.015Yb(2)O(3)-0.005 MgO and 0.92BaTiO(3)-0.08(Na0.5Bi0.5)TiO3-0.015Yb(2)O(3)-0.01MgO give a epsilon(r)& PRIME; variation within & PLUSMN;14% and & PLUSMN;10% in 20-165 & DEG;C. The core-shell microstructure should take account for the flattened epsilon(r)& PRIME;-T behavior of these samples.

Automated summary

The study found that the addition of different amounts of Yb(2)O(3)-MgO resulted in changes in the crystal structure of the ceramic material, forming a core-shell structure that significantly affected the dielectric properties of the material and led to a flat variation in the dielectric constant curve.