Effect of internal stresses on temperature-dependent dielectric properties of Fe-doped BZT ceramics

Ferroelectric, Piezoelectric and Dielectric Behaviors of CoO‐ and Fe2O3‐Doped BCZT Ceramics

“…The XRD patterns of BCZT‐ x Co and BCZT‐ x Fe ceramics are shown in Figure . The results showed that all patterns presented pure perovskite phase without secondary phase which were similar to previous reports on undoped BCZT, Pr‐doped Ba 0.98 Ca 0.02 Zr 0.02 Ti 0.98 O 3 , Fe‐doped BiYbO 3 ‐Pb(Zr,Ti)O 3 and Co‐doped Bi 0.5 Na 0.5 TiO 3 . From Rietveld analysis, the observed peaks for all samples could be indexed as the tetragonal structure with space group P4 mm.…”

“…The presence of oxygen vacancies due to charge neutrality requirement may also result in lattice expansion as observed in several CoO‐doped systems . In case of Fe 2 O 3 doping, the larger ionic radius of Fe 3+ (0.645 Å) compared to that of Ti 4+ (0.605 Å) should result in an expansion of the unit cell volume which was observed for the BCZT‐0.01Fe ceramic. However, for the BCZT‐0.03Fe sample, the unit cell slightly contracted .…”

“…It is known that, at B‐site, Fe ion may possess 2+ (0.780 Å), 3+ (0.645Å) and 4+ (0.585 Å) valences . The presence of Fe 4+ (0.585Å) replacing Ti 4+ (0.605 Å) may have small probability due to the unit cell distortion and charge imbalance . If this high‐valency Fe ion occupies at Ti 4+ site, the cohesive energy will increase and induce the shrinkage of the unit cell .…”

“…If this high‐valency Fe ion occupies at Ti 4+ site, the cohesive energy will increase and induce the shrinkage of the unit cell . In addition, Fe 3+ (0.645 Å) may replace Zr 4+ (0.720 Å) causing a contraction of the unit cell …”

“…Therefore, many studies attempted to investigate how to reduce the sintering temperature by doping the BCZT with other ions such as copper, cobalt, and praseodymium . Recently, it was found that the addition of cobalt oxide (Co 2 O 3 , CoO) or iron oxide (Fe 2 O 3 ) could improve the ferroelectric, dielectric, and piezoelectric properties in CoO‐Bi 0.5 Na 0.5 TiO 3 , Co 2 O 3 ‐Ba 0.95 Pb 0.05 TiO 3 , Co 2 O 3 ‐Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 , Co 2 O 3 ‐BaTiO 3 , Fe 2 O 3 ‐BaZr 0.1 Ti 0.9 O 3 , and Fe 2 O 3 ‐ (Na 0.5 K 0.5 ) 0.96 Li 0.04 Nb 0.86 Ta 0.1 Sb 0.04 O 3 . The purpose of this study is therefore to investigate the effects of CoO and Fe 2 O 3 addition on the physical properties, microstructure, dielectric, ferroelectric, and piezoelectric behaviors which have not been studied before in the BCZT ceramic.…”