Microwave dielectric properties of the Ag sub(1-x)Li sub(x)NbO sub(3) (x identical with 0 divided by 0.06) ceramics

Dielectric properties of the AgNbO sub(3) (AN) and Ag sub(1-x)Li sub(x)NbO sub(3) ceramics with x identical with 0.02, 0.04, 0.06 were investigated at microwaves (MW, 36 GHz) in the temperature range of 100 divided by 570 K, including the phase transitions in AN at 340K (weak ferroelectric - antiferroelectric) and at 530K (antiferroelectric-antiferroelectric). The results of MW measurements were compared with radio frequency and IR dielectric properties. No significant dielectric dispersion was observed. The anomalies of epsilon '(T) and epsilon double prime (T), corresponding to the phase transitions, were observed in AN and in Ag sub(1-x)Li sub(x)NbO sub(3). The Li additives for x less than or equal to 0.04 do not result in significant change of the MW dielectric properties. The ceramic with x identical with 0.06 shows a much lower MW epsilon ' below 250 K and a sharp step-like anomaly of epsilon '(T) at approximately 425 K. This indicates a significant change of the structure which is also confirmed by the pronounced change in the IR reflectivity.