Ferroelectric properties and phase transitions dynamics of Ag1-xLixNbO3 (x≤0.08) ceramics

The dielectric properties of Ag 1−x Li x NbO 3 (ALNx) ceramics (x ≤ 0.08) were investigated in a broad frequency range (20 Hz – 90 THz). Nature of the room temperature phase of ALNx (x ≤ 0.04) ceramics is ferrielectric while for x ≥ 0.05 ferroelectric. The frequency dependence of dielectric permittivity is mainly caused by the relaxational mode close to the ferrielectric/ferroelectric phase transition temperature and domains dynamics at lower temperatures. At room temperature and 10 GHz frequency the dielectric permittivity is quite high (270 for ALN0), while dielectric losses tanδ low (0.037 for ALN0) for all ALN compositions, therefore these ceramics are attractive for various microwave applications. Moreover, their piezoelectric properties were also investigated and the highest piezoelectric coefficient value was observed for ALN6 (200 pC/N at room temperature and 750 pC/N at 465 K). For ALNx ceramics when x ≥ 0.06 15 polar modes were distinguished in the IR spectra and 20 polar modes for ALNx ceramics with x < 0.06, however the number or modes is temperature independent in investigated temperatures range (103–500 K). • The dielectric properties of Ag 1−x Li x NbO 3 (ALNx) ceramics (x ≤ 0.08) were investigated in a broad frequency range (20 Hz – 90 THz). • The ferroelectric nature of ALN was confirmed by the polarization versus electric field measurements. • The microwave dielectric permittivity is high, while microwave losses low for ALN ceramics, therefore ceramics are attractive for applications. • The highest piezoelectric coefficient value was observed for ALN6 ceramics (200 pC/N at room temperature and 750 pC/N at 465 K).