Structure, electrochemical impedance and Raman spectroscopy of lithium-niobium-titanium-oxide ceramics for LTCC technology

• Published in: Ceramics international Vol. 47; no. 4; pp. 4944 - 4953
• Main Authors: Ivetić, Tamara B., Xia, Yang, Benzine, Omar, Petrović, Jelena, Papan, Jelena, Lukić-Petrović, Svetlana R., Litvinchuk, Alexander P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.02.2021
• Subjects: B. Spectroscopy; C. Electrical properties; D. Traditional ceramics; E. Functional applications; E. Functional applications; B. Spectroscopy; D. Traditional ceramics; C. Electrical properties
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2020.10.070

of Electrochemical Impedance Spectroscopy (EIS) are reported for lithium-niobium-titanium-oxide (LNTO) ceramics synthesized by a solid-state reaction method with two functional additives (MoO3 or ZnO) in the temperature range 323 K - 573 K and frequencies between 10−1 Hz and 107 Hz. Scanning electron microscopy (SEM) reveals a textured morphology of rod and plate-like particles that are typical for M-phase LNTO materials, while X-ray diffraction (XRD) analysis confirms the formation of an M-phase member compound with an approximate structure of Li7Nb3Ti5O21. Complex impedance analysis indicates that its overall electrical resistivity behavior depends mostly on the grain boundary processes. EIS analysis shows a negative temperature coefficient of resistance behavior (NTCR) in a defined temperature range in two LNTOs and thermal activation of the conduction mechanisms. The low dielectric constants of 5.5 and 12.1 at 1 MHz were found for the first and second LNTOs, respectively. Complimentary Raman spectroscopic measurements, despite very large crystallographic unit cell of LNTO, reveal only a small number of lines, which is the consequence of a “molecular” nature of materials.