Enhanced dielectric performance of Niobium and Thulium modified rutile TiO2 ceramics by defect regulation

• Published in: Ceramics international 2023-05, Vol.49 (9), p.14804-14811
• Main Authors: Guo, Xu, Kang, Jingrui, Gu, Rui, Hao, Honglei, Tang, Yi, Jin, Li, Wei, Xiaoyong
• Format: Article
• Language: English
• Subjects: Colossal permittivity; Defect chemistry; The secondary phase; TiO2
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2023.01.077

Colossal permittivity ceramic materials (CP, >103) have the potential of miniaturization and convenience for electric components. Unfortunately, they are often accompanied by high dielectric loss (>0.5), which limits their application. In this work, Ti1-x(Tm0.5Nb0.5)xO2 (TTNOx) ceramics are prepared via the solid state method. The results show that the main phase of doped samples maintains the rutile TiO2 phase and the average grain size decreases with increasing additive amounts. Gradually, the Tm2Ti2O7 phase appears and subsequently it is converted to the TmNbTiO6 phase. Furthermore, the low dielectric loss and colossal permittivity are synchronously achieved in doped ceramic samples by defect regulation. Especially, high permittivity of ∼1.61 × 105, low dielectric loss of ∼0.078 (1 kHz) and the AC resistivity of ∼10−9 s/cm are achieved in x = 0.01 samples at room temperature with good frequency and temperature stability. The true origin is deeply discussed by some analyses of XRD, XPS, SEM, Raman spectra and the complex impedance. The results show that enhanced dielectric performance originates from this fact that the addition of Nb and Tm ions triggers defective dipoles formation in grains, such as TiTi′/TmTi′−VO‥−TiTi′/TmTi′, TiTi′/TmTi′−NbTi∙, pinning the electron and limiting its long-range transition. Furthermore, the grain boundary resistivity is crucial to the ceramic conductivity. This study has driving implications for the application of colossal permittivity ceramic materials.