Preparation and dielectric properties of Ag1−xLixNbO3 (ALN) solid solutions ceramics

Ceramics of Ag1−xLixNbO3 (ALN) solid solutions were sintered for Li concentration range 0≤x≤0.1. They show a perovskite structure and exhibit the orthorhombic symmetry at room temperature. Low frequency (1 kHz–1 MHz) dielectric investigations were carried out for temperature range 120–920 K. The relaxor nature of weak ferroelectric M1 phase in silver niobate AgNbO3 was observed for first time. Three predominant aspects of Li substitution were found. The first one is associated with a large increase of spontaneous polarisation and with an emphasis on the relaxor character of the ferroelectric M1 phase. The second one is related to a gradual increase of the broad ε(T) maximum associated with the transition between disordered antiferroelectric M2 and M3 phases. The third one is connected with a large increase of thermal hysteresis of the main M3–O1 phase transition, which points to the martensitic nature of this phase transition. The Li substitution influence is discussed in terms of the appearance of electric dipole moments linked with the occupation of the off-centre positions by Li ions.