The degree of Zn2+ and Ta5+ ions ordering could play an important role in the dielectric loss in Ba(Zn1/3Ta2/3)O3 (BZT) ceramics. However, the influence of the grain size of Ba(B′1/3B″2/3)O3 ceramics with nano or sub-micron grains on the ordering domains structure is still not clear. In the present paper, highly dense (~98%) BZT microwave dielectric ceramics with homogeneous sub-micron structure (~330 nm) were prepared through spark plasma sintering (SPS). High resolution transmission electron microscopy combined with X-ray diffraction (XRD)clearly showed that the B-site ordering structure of sintered BZT samples by SPS becomes the B-site long-range 1:2 ordering as annealing proceeds. In contrast, the short-range 1:2 ordering in non-annealed counterparts was also present, which was not detectable by XRD. The size of B-site ordering domains enlarged with annealing temperature. The sub-micron structure of sintered BZT ceramics by SPS remained stable at up to 1400 C; however, the size of B-site 1:2 ordering domain was more than five times larger, which led to a significant increase of the quality factor (Q·f) to 37,700 GHz from 15,000 GHz.
In order to study the energy characteristics of seismic waves on the liquid CO2 blasting system, the blasting seismic wave signal of liquid CO2 blasting was obtained by on-site microseismic monitoring tests. The adaptive optimal kernel time-frequency analysis method was used to study the basic time-frequency properties of the seismic wave signal. Combining wavelet packet transform decomposition and reconstruction and adaptive optimal kernel time-frequency analysis method, the liquid CO2 energy distribution of the seismic wave signal was further analyzed. And the energy regression model of seismic wave source of liquid CO2 blasting system was discussed. The results show that the vibration velocity is at a low level, and the main frequency range is between 30 and 70 Hz, and the duration is about 20-30 ms. The energy is mainly distributed in 0-125 Hz, which is composed of two main regions. The power function model can be used to describe the attenuation law of the seismic wave energy. The energy conversion coefficient and characteristic coefficient of the source of liquid CO2 blasting system were defined and analyzed. Combined with the empirical formula of the Sadovsky vibration velocity, the energy regression model of the seismic wave source of liquid CO2 blasting system was obtained.
Influence of Mg and Mn doping on structure and microwave dielectric properties of Ba(Co 1/3 Nb 2/3 )O 3 (BCN) ceramics with complex perovskite structure is investigated systematically. X-ray diffraction and Raman spectrum investigations show that doping Mg and Mn into BCN ceramics is helpful for improving the quality factor (Q·fvalue) resulted from enhanced B-site 1:2 ordering degree. Mg-doped samples show higher ordering degrees and larger Q·fvalues than Mndoped counterparts. The sintering density, grain size, 1:2 B-site ordering structure and microwave dielectric properties of BCN ceramics show a strong dependence on Mg and Mn doping content. The sintering density of BCN ceramics can be increased significantly by doping a small amount of Mg and Mn. However, further increase in doping content results in the decrease of sintering density. τ f value of BCN ceramics can be tailored by doping of Mg into Co sites. The near-zero τ f value (∼0.64 ppm°C −1 ) is obtained when the Mg doping content is at x=0.1. The ordering degree and Q·fvalue of Mg-and Mn-doped BCN ceramics increase significantly with increasing annealing time.
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