The relaxation phenomena in irradiated PZT type piezoceramics

The samples of PZT type multi-component piezoceramics Pb0.075Ba0.01Ca0.01Sr0.005(Zr0.52Ti0.48)O-3 + 1.4 wt.% Bi2O3 + 0.3 wt% GeO obtained by hot pressing were shaped as (30x10x0.9) mm(3) plane-parallel plates. Some samples were subjected to polarization by low temperature method (T = 423 K, E-p = 30 kV/cm, t = 30 min), and others were gamma-irradiated (200 kGy, Co-60). For all specimens, temperature dependences of the internal friction Q(-1) and Young's modulus E were determined while heating at a rate of 3 K/min. The Q(-1)(T) curve shows two peaks P-R and P-F, located for non-irradiated sample at T-R = 380 K, T-F = 640 K, respectively. For samples irradiated at 200 kGy dose, the P-R peak shifts towards higher temperatures, while P-F, towards lower ones. The values of Young's modulus E are decreased in the area of the P-R and P-F peaks. At room temperature, the E value is 133 GPa for the non-irradiated sample and 150 GPa for the irradiated one. The relaxation peak P-R has been shown to be due to the domain boundary interaction with oxygen vacancies while the P-F one is related to the phase transition at the Curie point.