Bridgman growth, crystallographic characterization and electrical properties of relaxor-based ferroelectric single crystal PIMNT

摘要

According to the molar ratio of 0.25Pb(In_(1/2)Nb_(1/2))O_3-0.44Pb(Mg_(1/3)Nb_(2/3))O_3-0.31PbTiO_3, PIMNT poly-crystalline material was prepared by using the two-step coiumbite precursor route. Using the polycrystalline material prepared by solid-state reaction, 55 mm in diameter PIMNT single crystals with [110] orientation had been grown successfully by the seeded vertical Bridgman process with the optimum conditions. The crystal wafers on the [0 01 ]-cut were fabricated from the crystal boules oriented by the rotating orientation XRD method. As-grown crystal exhibits a peculiar phase evolution from rhombo-hedral to tetragonal phase along the growth direction due to the composition segregation in the crystal growth. As for [001]-oriented wafers fabricated from rhombohedral phase region, the crystal wafers exhibit a piezoelectric coefficient d_(33) of 1500-2100 pC/N, a dielectric permittivity s of 4600-5800 and a dielectric loss tan δ of 0.5-1%. Compare to the binary crystal PMNT, the ternary crystal wafers possess a higher phase transition temperature T_(r-t) of 100-120 °C, a higher Curie temperature T_c of 160-195 °C and a larger coercive field E_c of 4.2-5.0 kV/cm, which are favorable for the higher power ultrasonic devices with a wider working temperature range.