Effect of rare-earth substitution on the electrical properties and Raman spectroscopy of BCTZ ceramics
Résumé
A-site deficient rare-earth (Nd, Gd, and Y) doped (Ba0.99Ca0.01)(Zr0.2Ti0.8)O3 ceramics (noted BCTZ) were obtained by the conventional solid-state reaction method. X-ray powder diffraction experiments combined with first-order Raman scattering analysis were performed to provide detailed description of the structures with different ferroelectric/non-ferroelectric phases. Raman spectra investigations give evidence of compositional disorder as well as a significant change of polar order with the incorporation of rare-earth ions on the A-site of BCTZ lattice. The dielectric and ferroelectric properties of the (Ba1-xLn2x/3)0.99Ca0.01)(Zr0.2Ti0.8)O3 ceramics (x = 0 and x = 0.015, Ln = Nd, Gd and Y) were thoroughly investigated as a function of frequency and temperature.
This work highlights and demonstrates that the diffuseness of the phase transition increases and that the relaxor behavior is intensifies with rare-earth substitution. Moreover, the transition temperature is remarkably shifted to lower temperature for doped BCTZ ceramics. In the low temperature region, slim ferroelectric hysteresis loops with a low coercive field were observed for all compositions emphasizing their soft character.