| Popis: |
Using the method of solid-phase synthesis, we obtained ceramic samples with a structure like tetragonal tungsten bronzes, pure Ca0.3Ba0.7Nb2O6 (CBN30) and with modifying additives SrTiO3, KTaO3, or LiTaO3. The dispersion of the permittivity in the frequency range from 1 Hz to 10 MHz, the temperature dependences of the permittivity (in the given frequency range) and the pyroelectric coefficient are studied. It is shown that if the introduction of the LiTaO3 impurity into the composition of CBN30 destabilizes the dielectric characteristics at frequencies above 100 kHz, then the SrTiO3 impurity increases both the permittivity and the pyroelectric coefficient, significantly reducing dielectric losses at low (1-10 Hz) frequencies. At the same time, both of these impurities (SrTiO3 and LiTaO3) lead to sample depolarization during heating above 150oC, while the KTaO3 impurity, which slightly increases the permittivity and pyroelectric coefficient, does not affect the stability of the polarized state during heating up to higher temperatures. Keywords: piezoelectric ceramics, barium-calcium niobate, lead-free materials, permittivity dispersion, pyroelectric effect. |
