A lead-free multiferroic ceramic of BiFe0.96Sc0.04O3–BaTiO3 is a type of ABO3 perovskite structure, belonging to the R3c space group, but exhibiting poor insulation and weak multiferroicity.
Dy-modified K 0.5 Na 0.5 NbO 3 -based lead-free piezoelectric ceramics of (K 0.48 Na 0.48 Li 0.04 ) 1-x Dy x/3 (Nb 0.90 Ta 0.04 Sb 0.06 )O 3 lead-free piezoelectric ceramics were prepared by a conventional ceramics technique and the effects of Dy 3? doping on the crystal structure, microstructure, dielectric, piezoelectric and luminescent properties of the ceramics were investigated. The ceramics with low Dy levels (x B 0.015) show a pure perovskite structure, while a small amount of secondary phase DyNbO 4 can be detected in the ceramics with x C 0.02. The increase in the level of Dy 3? doping leads to the shift of crystal structure of the ceramics from the coexistence of orthorhombic-tetragonal phases to pseudo-cubic phase. The addition of Dy 3? inhibits the grain growth of the ceramics and induces the diffusive phase transition in the ceramics with high levels of Dy 3? ions. The piezoelectric constant d 33 of the ceramics decreases from 198 to 52 pC/ N with x increasing from 0 to 0.03 because of the shift of the crystal structure of the ceramics from the coexistence of orthorhombic-tetragonal phase to pseudo-cubic phase. The Dy-doped ceramics excited at 453 nm have excellent luminescent properties. Two strong emission spectral bands centered at 476 and 573 nm are observed, corresponding to the transition of the 4 F 9/2 ? 6 H 15/2 and 4 F 9/2 ? 6 H 13/2 levels of Dy 3? , respectively. Our study shows that the ceramic with x = 0.015 possesses simultaneously strong ferroelectricity, good piezoelectricity and excellent luminescence, suggesting that the Dy-doped ceramics may have potential application in multifunctional devices.
Multifunctional ceramics of 0.94(Bi0.984Er0.016Na)0.5TiO3–0.06BaTiO3 were prepared by a conventional ceramic technique. The effects of sintering temperature (Ts) and dwell time (ts) on the ferroelectricity, piezoelectricity, and fluorescence of the ceramics were studied. Furthermore, the influence of poling electrical field on the up‐conversion emission intensities was also discussed. As Ts and ts increase, the grains grow larger gradually and evolve from spheroid to rectangular shape. By increasing Ts and ts, the ferroelectricity of the ceramics is improved and the remnant polarization Pr increases. The optimum sintering temperature and dwell time for the piezoelectricity of ceramics are 1200 °C and 2 h, respectively. Also, both of the sintering temperature and dwell time make an important influence on the fluorescence of the ceramics. The ceramics sintered at 1140–1160 °C for 2 h possess excellent up/down‐conversion fluorescence. The up‐conversion emission intensity of the ceramics is further enhanced by optimizing poling electric field. This work develops a kind of multifunctional material that simultaneously possesses good ferroelectricity/piezoelectricity and excellent up/down‐conversion fluorescence by optimizing sintering temperature and dwell time.
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