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Dependencies of the complex permittivity of chromium-doped ferroelectric triglycine sulfate crystals (TGS + Cr) have been measured using dielectric spectroscopy method in a frequency range of 1–107 Hz and a temperature range of 23–60°C upon heating and cooling. The dielectric spectra are analyzed by considering the temperature‒frequency dependences of the real (e') and imaginary (e") parts of permittivity in the immediate vicinity of the phase transition using the dynamic conductance model and taking into account resonance processes. Good agreement between calculated and experimental data is obtained for the dielectric response of TGS + Cr crystal near the Curie temperature.

The temperature evolution of the dielectric spectra of TGS–TGS + Cr crystals (TGS stands for triglycine sulfate) with a periodic distribution of chromium impurity (Cr3+) has been studied in comparison with nominally pure TGS crystals in the frequency range from 10 to 107 Hz upon heating and cooling. It is shown that impurity crystals are characterized by the absence of dielectric dispersion in both measurement modes. An approach is proposed to explain the peculiarities of the dielectric dispersion of crystals with a periodic distribution of chromium impurity from the standpoint of mobile activity of certain elements of the TGS crystal structure.

A complex investigation of the domain structure and dielectric properties of triglycine sulfate (TGS) crystals containing profile layers doped with D,L-α-alanine (DLATGS) and L-α-alanine (LATGS) impurities is carried out. The images of the DLATGS and LATGS layers and ferroelectric domains are obtained by piezoelectric force microscopy; the parameters of the domain structure and the degree of unipolarity are determined. It is established that DLATGS layers are multidomain and LATGS stripes are mainly single-domain. The experimental data on the macroscopic dielectric properties of the crystals are compared with the results of a microscopic analysis of the domain structure.

A complex investigation of TGS–TGS + Cr crystals with a profile impurity distribution of chromium ions Cr3+ has been carried out at the macrolevel (measurement of dielectric properties by the method of nematic liquid crystals) and microlevel (domain structure according to atomic force microscopy data). It is established that periodic doped layers are formed only in individual growth pyramids in the regions where the polarization vector has a nonzero component along the normal to the growth faces rather than throughout the entire crystal volume. The domain configuration at the boundary of growth layers with different impurity compositions has been studied by piezoelectric force microscopy. The static unipolarity of layers with and without chromium impurity is approximately identical, whereas the domain-wall density in doped regions is higher than that in undoped ones by a factor of about 7.

A precision study of slow polarization in a polydomain ferroelectric has been performed on an example of triglycine sulfate samples in weak electric fields prior to and upon their γ-irradiation at doses of 0.2 and 0.3 Mrad. It is shown that in all the cases, relaxation obeys the universal temporal power law. The phenomenological analysis of the experimental data was performed in the approximation of noninteracting relaxation centers (nuclei), which provided the restoration of the spectra of potential barrier distribution for domain walls in the crystal. The transformation of the spectrum of a γ-irradiated ferroelectric indicates the simultaneous formation of new small and gigantic barriers in the crystal.