Bismuth zinc niobate pyrochlore Bi1.5ZnNb1.5O7 from a polymeric urea-containing precursor

Cubic bismuth zinc niobate pyrochlore (Bi1.5ZnNb1.5O7) nanopowder was synthesized by a urea-modified polymeric precursor method. The pH of the chemical solution was stabilized through the homogeneous decomposition of urea, and the influence of the urea content was evaluated. The powders were obtained after pre-treatment at 300 and 400 °C for 4 h, followed by heat treatment at different temperatures (500, 600 and 700 °C) for 2 h. The DSC results indicate that the cubic pyrochlore phase (α-BZN) crystallizes at temperatures as low as 500 °C. The crystallization process was followed by XRD, which revealed that no detectable intermediary phases such as BiNbO4 or a pseudo-orthorhombic pyrochlore were observed at any time. The powder obtained presents large agglomerates of clusters of nanoparticles of around 50 nm, which were examined by TEM.