High-relative-dielectric-constant bismuth–niobium–oxide films prepared using Nb-rich precursor solution

Various ceramic materials have been developed for electronic devices. Bismuth– niobium–oxide(BNO) films prepared by a chemical solution deposition (CSD) method have the cubic pyrochlorephase, high relative dielectric constant, and low tangent loss (tan δ). We found that a BNO cubic pyrochlorecrystal was Nb-rich, even though its pyrochloreformula is A2B2O7. The crystallization temperature of BNO increased with increasing Nb ratio. The relative dielectric constants of BNO films were related to the Nb ratio in the precursor solution. The dielectric constant of the BNO films was 250 when the Bi and Nb ratios in BNO precursor solutions were 4 and 6, respectively, and the sintering temperature was 600 °C. In addition, the tan δ was less than 0.01 at 1 kHz, which is higher than the reported values of BNO systems despite using the CSD method. These results show that the properties of BNO films prepared by the CSD method were associated with the Nb ratio in the precursor solution. Furthermore, the dielectric characteristics indicated that the Nb-rich BNO films have potential applications in electronic devices.