Процессы переключения в керамике твердых растворов на основе Ca-=SUB=-0.3-=/SUB=-Ba-=SUB=-0.7-=/SUB=-Nb-=SUB=-2-=/SUB=-O-=SUB=-6-=/SUB=-

Abstract

In this work, ceramic samples with a structure of the type of tetragonal tungsten bronzes, composition Са0.3Ba0.7Nb2O6 (CBN30) pure and with modifying additives SrTiO3, KTaO3 or LiTaO3 (5 mass %) were studied by the oscillographic method. It is shown that the introduction of modifying additives into CBN30 ceramics leads to an increase in the reversal polarization and to a decrease in dielectric losses, both at room temperature and at high temperatures. The introduction of LiTaO3 impurity into the CBN30 composition leads to the greatest increase in the reversal polarization. In contrast to ceramics based on lead zirconate titanate, which have a perovskite type structure, the introduction of SrTiO3 into CBN30 (having the structure of tetragonal tungsten bronzes) does not significantly improve the ferroelectric properties. It has been found that at temperatures above 100 °C for pure CBN30 ceramics, above 165 °C for CBN30 + 5% SrTiO3 and CBN30 + 5% KTaO3, and above 200 оС for CBN30 + 5% LiTaO3, there is a strong increase in dielectric losses. The contribution of dielectric losses to switching processes makes it impossible to determine the temperature of the ferroelectric phase transition for solid solutions based on CBN30 from the temperature dependences of dielectric hysteresis loops.