Colossal Permittivity Characteristics of (Nb, Si) Co-Doped TiO2 Ceramics

• Published in: Materials Vol. 15; no. 13; p. 4701
• Main Authors: Kotb, Hicham Mahfoz, Alshoaibi, Adil, Mazher, Javed, Shaalan, Nagih M., Ahmad, Mohamad M.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 05.07.2022; MDPI
• Subjects: Barrier layers; Ceramics; Dielectric loss; Dielectric properties; Dielectrics; Diffraction patterns; Frequency ranges; Grain growth; Grain size; Permittivity; Raman spectra; relative permittivity; relaxation; Silicon dioxide; sintering; Solid solutions; Spectrum analysis; Titanium dioxide; X-ray diffraction; United States > US
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15134701

(Nb5+, Si4+) co-doped TiO2 (NSTO) ceramics with the compositions (Nb0.5Si0.5)xTi1−xO2, x = 0, 0.025, 0.050 and 0.1 were prepared with a solid-state reaction technique. X-ray diffraction (XRD) patterns and Raman spectra confirmed that the tetragonal rutile is the main phase in all the ceramics. Additionally, XRD revealed the presence of a secondary phase of SiO2 in the co-doped ceramics. Impedance spectroscopy analysis showed two contributions, which correspond to the responses of grain and grain-boundary. All the (Nb, Si) co-doped TiO2 showed improved dielectric performance in the high frequency range (>103 Hz). The sample (Nb0.5Si0.5)0.025Ti0.975O2 showed the best dielectric performance in terms of higher relative permittivity (5.5 × 104) and lower dielectric loss (0.18), at 10 kHz and 300 K, compared to pure TiO2 (1.1 × 103, 0.34). The colossal permittivity of NSTO ceramics is attributed to an internal barrier layer capacitance (IBLC) effect, formed by insulating grain-boundaries and semiconductor grains in the ceramics.