Growth and some electrical properties of Pb(Co1/3Nb2/3)O3-PbTiO3 crystals prepared by a Bridgman method

A large single crystal of relaxor-based ferroelectrics Pb(Co1/3Nb2/3)TiO3-PbTiO364/36 has been grown by using a Bridgman method. After a primary PCNT64/36-PbO phase diagram was studied, the crystal was found to be of perovskite structure with high thermal stability, which enabled a melt method suitable for its growth. The PCNT64/36 crystal grown from Mg2+ doped PCNT seed crystal contains 0.20 wt%MgO and shows a tetragonal structure and the Curie temperature of 143 °C, which is much lower than Tc of PCNT62/38 ceramics near MPB. The thermal analysis (DTA and TG) curves, XRD data for crystals undergoing high-temperature annealing and the good homogeneity in Tc, composition and structure seem to suggest that PCNT64/36 crystal is approximately of pseudo congruent melting. Owing to its tetragonal structure and conductivity, the as-grown PCNT64/36 crystal exhibited large dielectric loss and lower piezoelectric response.