Synthesis and dielectric properties of Ag(Nb0.6Ta0.4)O3 ceramics prepared by solid-state and sol–gel methods

Ag(Nb0.6Ta0.4)O3 (ANT) ceramics were synthesized by conventional solid-state method and wet chemical method (sol–gel method). The effects of preparation methods on synthesis temperature, phase structure, morphology, Raman spectra, and dielectric properties of ANT ceramics were investigated. For sol–gel method, K2CO3 was used to dissolve Nb2O5 and Ta2O5, avoiding use of strong corrosive hydrofluoric acid. The results showed that the synthesis temperature of ANT phase obtained by sol–gel method was 700 °C, while that by solid-state method was 950 °C. The nanopowders around 40 nm were obtained by sol–gel method, while the micro-powders around 1.5 μm by solid-state method. In addition, the decrease of vibration frequency of A1g(O) stretch mode indicated that the Nb–O or Ta–O bonds became weak, which lead to high permittivity. The dielectric properties of the ceramics prepared by the two methods were different. Notably, the dielectric loss (6.6 × 10−4) of ANT ceramic synthesized by sol–gel method was much lower than that (22.8 × 10−4) by solid-state method.