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

Results: 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 10(7) 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 Li(7)Nb(3)Ti( )5O(21). 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.

Automated summary

Electrochemical Impedance Spectroscopy (EIS) was conducted on lithium-niobium-titanium-oxide (LNTO) ceramics synthesized using a solid-state reaction method with two functional additives. Results showed that the overall electrical resistivity behavior of LNTO depends on grain boundary processes, exhibiting a negative temperature coefficient of resistance behavior and thermal activation of conduction mechanisms within a defined temperature range. Additionally, LNTO materials showed low dielectric constants of 5.5 and 12.1, indicating significant differences in properties.