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The dielectric behaviors of (1−x)Pb(Mg 1/3 Nb 2/3 )O 3 −xPb(Zr 0.53 Ti 0.47 )O 3 (PMN-PZT) relaxor ferroelectric ceramics of several compositions (x = 0.05-0.30) have been studied under high bias electric field. The dielectric constant decay with dc electric field was observed in the range of diffuse phase transitions. The nonlinear dielectric response was considered in frames of thermodynamic approach. It was shown also that all dielectric features may be understood using a model involving heterogeneous polar micro-and nanoregions.

The temperature dependence of the local order parameter and relaxation time distribution function have been determined in (1 – x)PMN–xPZT ceramic samples via dielectric permittivity. Above the Burns temperature, the permittivity was found to follow the Currie–Weiss law, and with temperature decreasing the deviation was observed to increase. A local order parameter was calculated from the dielectric data using a modified Landau–Devonshire approach. These results are compared to the distribution function of relaxation times. It was found that a glasslike freezing of reorientable polar clusters occurs in the temperature range of diffuse relaxor transition. The evolution of the studied system to more ordered state arises from the increased PZT content. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Investigations in recent decades have shown that the combustion mechanism of metal particles changes dramatically with diminishing size. Consequently, theoretical description of the ignition and combustion of metal nanoparticles requires additional research. At the same time, to substantiate theoretical models, it is necessary to obtain objective experimental information about characteristics of ignition and combustion processes, which is associated with solving serious technical problems. The presented review analyzes specific features of existing experimental methods implied for studying ignition and combustion of metal nanoparticles. This particularly concerns the methods for correct determination of nanoparticles size, correct description of their heat-exchange parameters, and determining the ignition delay and combustion times. It is stressed that the problem exists of adequate comparison of the data obtained with the use of different techniques of particles’ injection into a hot gas zone and the use of different methods of reaction time measurement. Additionally, available in the literature, data are obtained for particles of different material purity and different state of oxide layer. Obviously, it is necessary to characterize in detail all relevant parameters of a particle’s material and measurement techniques. It is also necessary to continue developing advanced approaches for obtaining narrow fractions of nanoparticles and for detailed recording of dynamic particles’ behavior in a hot gas environment.