Microwave dielectric properties of the Ag1−xLixNbO3(x = 0 ÷ 0.06) ceramics

Dielectric properties of the AgNbO3 (AN) and Ag1−xLixNbO3 ceramics with x = 0.02, 0.04, 0.06 were investigated at microwaves (MW, 36 GHz) in the temperature range of 100 ÷ 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 e′(T) and e″(T), corresponding to the phase transitions, were observed in AN and in Ag1−xLixNbO3. The Li additives for x ≤0.04 do not result in significant change of the MW dielectric properties. The ceramic with x = 0.06 shows a much lower MW e′ below 250 K and a sharp step-like anomaly of e′(T) at ≈ 425 K. This indicates a significant change of the structure which is also confirmed by the pronounced change in the IR reflectivity.