Dielectric studies of Ba2PrxNd1−XFeNb4O15 ceramics

We have investigated dielectric response of Ba₂Pr_xNd_1-xFeNb₄O₁₅ ceramics (x = 0, 0.2, 0.5, 0.6, 0.8, 1) in the frequency range from 20 Hz to 1 GHz. Obtained results showed a continuous transformation from the ferroelectric behavior of Ba₂NdFeNb₄O₁₅ to the pure relaxor response of Ba₂PrFeNb₄O₁₅ with increasing x. For intermediate x values coexistences of both ferroelectric transition and relaxor dielectric signatures corresponding to two different phenomena in the framework of these materials were observed. The increase of Pr amount lowers ferroelectric phase transition temperatures in these compounds and also a huge cooling-heating hysteresis exceeding 50 K was observed, which origin is under discussion yet.