Features of the structural states of KNbO3 single crystals before and after fast-neutron irradiation

Resumo

Neutron irradiation is a unique tool for forming new structural states of ferroelectrics, which cannot be obtained by conventional methods. The inf luence of the irradiation by two doses of fast neutrons (F = 1 × 10¹⁷ and 3 × 10¹⁷ cm^–2) on the structure and properties of KNbO₃ single crystals has been considered for the first time. The developed method for taking into account the experimental correction to the diffuse scattering has been used to analyze the structural changes occurring in KNbO₃ samples at T = 295 K and their correlations with the behavior of dielectric and nonlinear optical characteristics. The irradiation to the aforementioned doses retains the KNbO₃ polar structure, shifting Т_С to lower temperatures and significantly affecting only the thermal parameters and microstructure of single crystals. Neutron irradiation with small atomic displacements provides a structure similar to the high-temperature modification of an unirradiated KNbO₃ crystal.