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The Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics added with Bi2O3–B2O3–SiO2 glass were synthesized by the sol-gel method, and the effect on their microstructural, dielectric, energy storage properties has been discussed. The SEM results demonstrate that the average grain size decreases obviously with reducing glass additive, which is enriched at the grain boundary. Owing to the addition of glass additive, sintering temperature decreases significantly. Moreover, the glass additives broaden the dielectric peak and the Curie temperature shifts toward lower temperature. The ceramic with glass additive shows better impedance properties than that of pure BCZT ceramics. In addition, the coercive field and remnant polarization of hysteresis loop were greatly decreased by introducing glass additives in BCZT ceramics. Notably, the sample with 5% glass additive shows the highest energy storage density (2.12 J/cm3) and the largest storage efficiency (90.5%) at 330 kV/cm electric field. These findings provide a potential pathway to enhance energy storage properties of BCZT ceramics in order to promote its energy storage application in practice. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations were performed to investigate dynamic evolution in metallic glassforming liquids during quenching from high temperature above melting point down to supercooled region. Two crossover temperatures TA and TS (TA>TS) are identified, and their physical meanings are clarified. TA and TS are found to be not only the sign of dynamic crossover phenomena but also the manifestation of two key structure correlation lengths ξs. As temperature decreases below TA, ξs goes beyond the nearest-neighbor distance, resulting in the Arrhenius-to-non-Arrhenius transition of structural relaxation time and the failure of Stokes-Einstein (SE) relation. As TS is traversed, the increase rate of ξs reaches the maximum, leading to the simultaneous appearance of dynamical heterogeneity and fractional SE relation. It is further found that structure correlation increases much faster than dynamic correlation, playing a role of structural precursor for dynamic evolution in liquids. Thus, a structural link is established for deeper understanding dynamic crossover phenomena. [ABSTRACT FROM AUTHOR]

An aqueous solution of carbon nanotubes, treated by a concentrated nitric/sulfuric acid mixture to disentangle the nanotubes, was utilized as the working medium in a two-phase closed thermosyphon to investigate its performance. In comparison with the thermosyphon filled with a distilled water medium, the one filled with carbon nanotube suspension has a high evaporation section wall temperature, incipience temperature, and excursion, as well as thermal resistance. The carbon nantotubes’ nanofluid deteriorates the performance of the gravity-assisted heat pipe. Measurements employing the maximum bubble pressure method demonstrate that suspending carbon nanotubes in bulk water gives rise to increased surface tension. In addition, the contact angle of suspension obtained with the sessile drop method on a copper plate is much smaller than that of water. Alterations of solid-liquid-vapor interfacial properties, arising from the addition of carbon nanotubes, change the boiling mechanism and thus deteriorate the boiling heat transfer. [ABSTRACT FROM AUTHOR]

Single phases of double layered perovskitelike Sr2-xGdxFeMoO6 samples with x varying from 0.00 to 0.25 have been synthesized. Distortion in FeO6 and MoO6 octahedrons is characterized by Rietveld refinements using the powder x-ray diffraction data. Antisite defects are considered during the refinements. Positron annihilation spectroscopy shows us that the density of antisite defects increases with increasing x. The size of defects reaches the largest values, and conducting electrons are most extensive in sample with x=0.20. The insulating behavior is observed. We argue that the valence states between Fe and Mo play the critical role in magnetism and transition properties in Gd doped Sr2FeMoO6. [ABSTRACT FROM AUTHOR]

Single phases of double layered perovskitelike Sr2-xGdxFeMoO6 samples with x varying from 0.00 to 0.25 have been synthesized. Distortion in FeO6 and MoO6 octahedrons is characterized by Rietveld refinements using the powder x-ray diffraction data. Antisite defects are considered during the refinements. Positron annihilation spectroscopy shows us that the density of antisite defects increases with increasing x. The size of defects reaches the largest values, and conducting electrons are most extensive in sample with x=0.20. The insulating behavior is observed. We argue that the valence states between Fe and Mo play the critical role in magnetism and transition properties in Gd doped Sr2FeMoO6. [ABSTRACT FROM AUTHOR]