Electrical properties and Curie temperature of Li/Ce co-doped BaBi4Ti4O15-Bi4Ti3O12 intergrowth ceramics

Li/Ce co-doped BaBi4Ti4O15-Bi4Ti3O12 (BBT-BIT) intergrowth bismuth layer-structured piezoelectric ceramics were prepared by conventional solid-state method. The X-ray diffraction, Raman spectroscopy, and scanning electron microscopy results showed that all the samples had a single orthorhombic phase structure, indicating that Li/Ce dopants had successfully dissolved into the BBT-BIT lattice. Li/Ce co-doping improved the piezoelectric properties of the ceramics: d33 increased from 6.8 pC/N to 21.4 pC/N and the Curie temperature Tc increased from 483 degrees C to 544 degrees C. Among all the ceramics investigated, the Ba0.7(Li0.5Ce0.5)0.3Bi8Ti7O27 ceramic showed the best comprehensive properties with d33 = 20.2 pC/N, Tc = 540 degrees C, tan& = 0.53%, Ea = 1.13 eV, 2Pr = 10.5 mu C/cm2. Meanwhile, the hysteresis loop of the BBT-BIT-0.3(Li0.5Ce0.5) sample sintered in an oxygen atmosphere was asymmetric, which may have been caused by defects produced by the Li/Ce co-doped. Besides, a d33 value of 18.5 pC/N was achieved at 450 degrees C, which is 91.6% of the value at room temperature, indicating the good thermal stability of the ceramic. The sample showed high resistivity, which can be attributed to the decrease in the concentration of the oxygen vacancies. Our results suggest the great potential of Li/Ce co-doped BBT-BIT intergrowth piezoelectric ceramics for high-temperature applications.