We demonstrate improper ferroelectric and non-relaxor behaviour of the [(CH3)2NH2][Zn(HCOO)3] hybrid perovskite framework.

In ferroelectrics, the effects of acceptor doping on electrical and electromechanical properties, often referred to as the “hardening” effects, are commonly related to domain-wall pinning mechanisms mediated by acceptor–oxygen-vacancy defect...

The technologies of Unmanned Aerial Vehicles (UAVs) are fast emerging, but as any other technology, development of UAVs provides not only benefits but also the threats. UAV technologies are developing much faster than means of their control and detection. RADAR technology is one of the means of UAV's detection. Usually, radars are expensive, and usage of high-power radiation is problematic in many cases.Today's market provides low cost marine radar working on various principles of operation. Such radar are not optimal, but could be used for UAV detection. Detection possibility of UAVs by FMCW marine radar was investigated by using two types of small UAVs as targets.

PbMg1/3Nb2/3O3 (PMN) is a well known ferroelectric relaxor. PMN crystal doped with La3+ has greatly enlarged chemically ordered regions (CORs) in the structure. It is interesting to know how the development of CORs influences physical properties of PMN crystal. In this work, dielectric properties and distribution of relaxation times of PMN and 0.98Pb(Mg1/3Nb2/3)O3–0.02La(Mg2/3Nb1/3)O3 (PLMN) crystals are studied. The experiment was performed in 120–500 K temperature range and wide frequency range—up to 46 GHz. The results demonstrate that the relaxor behaviour of PMN and PLMN is qualitatively the same in spite of the fact that chemical ordering is very different.

The full-wave analysis was applied for a coaxial line (i.e., transmission line) that has a “short-circuited” discontinuity. The discontinuity has a radius less than or equal to the inner radius of the coaxial line. The “sample region” can be considered as a partially filled circular waveguide. Such a structure is very practical and is of particular interest for the dielectric spectroscopy applications. It takes into account the inhomogeneous field distribution, which is the limiting factor for the determination of high dielectric permittivity values at microwave frequencies. The direct problem was solved by using the mode-matching technique, and the relationship between the complex reflection coefficient and the dielectric permittivity of the cylindrical sample was obtained. By solving the inverse problem, it is possible to obtain the complex dielectric permittivity from the experimental values of the scattering matrix. The results were verified by the finite element modeling of the system and applied for particular materials. The correspondence between these approaches is excellent. This method is very suitable for the determination of permittivity, which exceeds several thousands (it is applicable for any type of material). It extends the frequency range where the permittivity can be determined reliably. There is no necessity to prepare samples with different geometries (i.e., surface area and thickness).