In situ imaging of domain structure evolution in labgeo5 single crystals

LaBGeO5 (LBGO) crystals are unique ferroelectric materials for manufacturing highly efficient UV laser sources based on frequency conversion. This is due to their low cut-off wavelength, high nonlinear-optical coefficients, and non-hygroscopicity. Periodical poling requires a deep study of domain kinetics in these crystals. Domain imaging by Cherenkov second harmonic generation microscopy was used to reveal the main processes of domain structure evolution: (1) growth and merging of isolated domains, (2) growth of stripe domains formed on the artificial linear surface defects, and (3) domain shrinkage. In a low field, growth of triangular domains and fast shape recovery after merging were observed, while in a high field, the circular domains grew independently after merging. The revealed essential wall motion anisotropy decreased with the field. The anisotropy led to significant shape transformations during domain shrinkage in low field. The formation of short-lived triangular domains rotated by 180 degrees with respect to the growing isolated domains was observed. The obtained results were explained within the kinetic approach to domain structure evolution based on the analogy between the growth of crystals and ferroelectric domains, taking into account the gradual transition from determined nucleation in low field to the stochastic one in high field. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 19-12-00210Funding: This research was funded by the Russian Science Foundation, grant number 19-12-00210

Specific heat of a PIN-PMN-PT single-crystal up to 500K

The temperature dependence of the specific heat of the single crystal Pb(In0.5Nb0.5)O3-Pb(Mg1∕3Nb2∕3)O3-PbTiO3 (PIN-PMN-PT) was obtained at 80–500K by means of ac-calorimetry, and comparison with the calorimetric data for PMN was made, allowing one to determine absolute values of the specific heat of PIN-PMN-PT. For the high-temperature region (T>200K), the background heat capacity was calculated, the anomalies of the heat capacity for both compounds were determined, and the hump of the temperature dependence of specific heat PIN-PMN-PT was detected for the first time

Evidence of Substrate-Induced Ferroelectric Phase Transition in SrTiO3 by Means of Thermal Measurements

The paper reports the results of the temperature dependence measurements of the specific heat for a SrTiO3 thin (104 nm) film deposited on a DyScO3 substrate. Two anomalies of the specific heat have been observed. They can be associated with the strain-induced ferroelectric phase transition (at 304K) and the shifted antiferrodistortive structural phase transition (at 173 K).

Features of Phase Transitions in Nanostructured Ferroelectric Oxides Revealed from Calorimetric Data

A short review of the study of thermal properties of the nanostructured ferroelectrics is given. An application of the modern calorimetric technique to a comparative study of phase transitions in the ferroelectric nanostructured materials (polycrystalline and epitaxial thin films, superstructures, ferroelectric heterostructures, substrate-induced ferroelectricity) is considered.