Structural and dielectric behavior of giant permittivity SrNbxTi1−xO3 ceramics sintered in nitrogen atmosphere

SrNbxTi1−xO3 (0.000≤x≤0.015, SNT) ceramics were prepared via a traditional solid state reaction method and sintered in nitrogen atmosphere at 1530 °C. SrNb0.003Ti0.997O3 ceramics exhibit a giant permittivity of about 40,000 and low dielectric loss of 0.027 measured at room temperature and 1 kHz, which is better than that of SNT ceramics sintered in oxygen atmosphere. The crystalline structure, surface morphology, element valance state and dielectric properties of SNT ceramics were investigated, and the mechanism of this giant permittivity effect was explored. The results indicated that the introduction of Nb5+ would be the likely reason for the partial reduction of Ti4+ to Ti3+ (Ti4+∙eTi4+∙e) in SNT ceramics. Both Nb5+ and fully ionized oxygen vacancies caused by oxygen-poor sintering environment contributed to this giant permittivity and low dielectric loss existed in SNT ceramics sintered in nitrogen atmosphere.