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In this work, (1-x)(Pb0.97La0.02)(Zr0.5Sn0.44Ti0.06)O3-x BiNbO4 (x = 0–0.15) ceramics ((1-x)PLZST-xBiNbO4) were prepared by solid state reaction method. By changing the content of BiNbO4, the phase evolution, dielectric properties and energy storage properties were studied comprehensively. It is found that with the increase of BiNbO4 content, there are two peaks of dielectric constant. The mild BiNbO4 doping first destroyed the relaxation behavior of PLZST. Then with the increase in BiNbO4, the local defect dipole forms another weak coupling and reduce the antiferroelectric-ferroelectric phase transition field (EAFE-FE). When x = 0.05, the maximum energy density is 0.82 J/cm3, and the energy efficiency is 88%. [ABSTRACT FROM AUTHOR]

In this work, (1-x)(Pb0.97La0.02)(Zr0.5Sn0.44Ti0.06)O3-x BiNbO4 (x = 0–0.15) ceramics ((1-x)PLZST-xBiNbO4) were prepared by solid state reaction method. By changing the content of BiNbO4, the phase evolution, dielectric properties and energy storage properties were studied comprehensively. It is found that with the increase of BiNbO4 content, there are two peaks of dielectric constant. The mild BiNbO4 doping first destroyed the relaxation behavior of PLZST. Then with the increase in BiNbO4, the local defect dipole forms another weak coupling and reduce the antiferroelectric-ferroelectric phase transition field (EAFE-FE). When x = 0.05, the maximum energy density is 0.82 J/cm3, and the energy efficiency is 88%. [ABSTRACT FROM AUTHOR]

Methane-air explosions are the most fatal accidents in underground coalmines. To understand its destruction, a worst-case full-scale methane-air explosion at a longwall coalface was simulated and analyzed based on accident investigations. It was found the flame covers a short length with an expansion ratio of about 6.67 at the longwall coalface, and crosscuts reduce the ratio to 3.67. Bifurcation reduces the peak overpressure by 25%–32% and the peak velocity of blast waves by 18.5%–23.5%. Corners have a significant effect on mitigating the peak overpressure but have a negligible impact on the blast velocity. In a long straight tunnel, the peak overpressure and blast velocity decay slowly and linearly by just 18.5% and 17.3%. A high-speed blast wave with debris and toxic and anoxic airflows at a velocity higher than 100 m/s were obtained from the accident investigations and in most of the simulation domain, it is the biggest challenge to evacuation and the most destructive force at the far-field disaster areas of methane-air explosions in underground coalmines. Thus, crosscuts, corners and blast velocity retarding methods should be more adopted to mitigate explosions and improve the rescue and evacuation safety. [ABSTRACT FROM AUTHOR]