Influence of Co/W co-doping on structural and electrical properties of Na0.5Bi2.5Nb2O9 piezoelectric ceramics

Co/W co-doped Na0.5Bi2.5Nb2-x(Co1/3W2/3)xO9 (NBNCW-x) ceramic samples were prepared by the conventional solid state reaction method. The electrical properties and crystal structure of the NBNCW-x ceramic samples were analyzed in detail. The XRD and Rietveld refinement results showed that the samples lattice distortion decreased with the increment of Co/W doping. The XPS results showed that the number of oxygen vacancies in the Na0.5Bi2.5Nb2O9 ceramics could be reduced by the substitution of a small amount of Co/W. The weakened lattice distortion and reduced number of oxygen vacancies of the Na0.5Bi2.5Nb2O9 ceramics synergistically contributed to its improved electrical properties. In particular, the Na0.5Bi2.5Nb1.97(Co1/3W2/3)0.03O9 ceramic exhibited the best performance, and its Tc, d33 and Pr were 780 degrees C, 24.9 pC/N and 12.6 mu C/cm2, respectively. The dielectric loss was only 3.3% at 550 degrees C. In addition, this ceramic exhibited excellent thermal stability, with the d33 value of the ceramic being 95.2% of its original value when annealed at 750 degrees C. These properties indicate that the Co/W co-doped Na0.5Bi2.5Nb2O9-based ceramics have potential application in the high-temperature field.