Xinyu Zeng,Yang Li,Jia Dong,Jingli Li,Zhaoyu Yang,Chunlin Song,Gang Liu,Yan Yan
In the current study, a series of CeO 2 -doped ( x = 0.01, 0.015, 0.02, 0.025 mol) ceramic samples were prepared, and the valence of Ce in the perovskite was analyzed in detail, revealing the polarization contribution and effect mechanism of the doped Ce element in the 0.65BaTiO 3 –0.35Sr 0.7 Bi 0.2 TiO 3 ceramic. The phase structure and electrical stored energy performance of the resulting ceramics were also characterized. It was found that adding an appropriate amount of CeO 2 to BaTiO 3 was helpful for improving the relaxor behavior, promoting electric storage, and releasing ceramic materials. Particularly, the electric breakdown strength of the 0.02Ce-doped specimen reached 330 kV/cm, and the corresponding density and efficiency were 2.57 J/cm 3 and 81.30%, respectively. In addition, doping with Ce caused the ceramics to exhibit good stability at frequencies of 1–300 Hz and over a temperature range of 30–150 °C. A high current density ( C D ) and power density ( P D ) were obtained in charge–discharge tests.
A series of Ce 2 [Zr 1- x (A) x ] 3 (MoO 4 ) 9 (A = Sr 1/3 Ta 2/3 , Sr 1/3 Sb 2/3 ; x = 0.02, 0.04, 0.06, 0.08 and 0.10) (abbreviated as CZ 1- x T x and CZ 1- x S x ) microwave dielectric ceramics were studied systematically with respect to microstructures, sintering behaviors, crystal structures, microwave dielectric properties and infrared vibrational modes. Density measurements and scanning electron microscopy (SEM) reveal the dense and homogeneous microstructures. X-ray diffraction (XRD) results confirm the formation of solid solutions belonging to the hexagonal system with a R 3 ‾ c space group, and the lattice volume increases with raising the doping content. Furthermore, the complex chemical bond theory was used to calculate the intrinsic bond parameters, and the correlations between the microwave dielectric properties and intrinsic bond parameters were established. Finally, far infrared (FIR) spectra reveal that the main polarization contribution stems from the absorptions of the phonon oscillations in these two groups of ceramics. Typically, the optimum microwave dielectric properties are achieved for CZ 0.9 T 0.1 and CZ 0.94 S 0.06 ceramics with ε r = 10.24, Q × f = 92,009 GHz (at 9.70 GHz), τ f = −8.84 ppm °C −1 and ε r = 10.40, Q × f = 82,696 GHz (at 9.69 GHz) and τ f = −8.04 ppm °C −1 , respectively. Interestingly, the CZ 0.9 T 0.1 ceramic exhibits the maximum Q × f value in the ion doped Ce 2 Zr 3 (MoO 4 ) 9 ceramics while retaining a good τ f = −8.84 ppm °C −1 .
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