Ionic conduction and crystal structure of aluminum doped NASICON-type LiGe2(PO4)3 glass-ceramic crystallized at different times and temperatures

• Published in: Journal of electroceramics Vol. 40; no. 3; pp. 180 - 189
• Main Authors: Illbeigi, Mohammad, Fazlali, Alireza, Kazazi, Mahdi, Mohammadi, Amir H.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2018; Springer Nature B.V
• Subjects: Aluminum; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Conductors; Crystal structure; Crystallization; Crystallography and Scattering Methods; Electrochemistry; Electron microscopy; Field emission microscopy; Glass; Glass ceramics; Grain boundaries; Ion currents; Lithium; Lithium ions; Materials Science; Microcracks; Natural Materials; Optical and Electronic Materials; Spectrum analysis; X-ray diffraction; Lithium ion conduction; Crystallization time; Microstructure; NASICON-type glass-ceramic; Crystallization temperature
• ISSN: 1385-3449; 1573-8663
• DOI: 10.1007/s10832-018-0118-1

In this communication, NASICON-type glass-ceramic (lithium germanium phosphate, LiGe 2 (PO 4 ) 3 ) was prepared as lithium super ionic conductor using aluminum as dopant for ionic conduction improvement. The solid solution was Li 1 + x Al x Ge 2-x (PO 4 ) 3 (x = 0.5) that Ge 4+ ions were partially substituted by Al 3+ ions in crystal structure. Initial glasses were converted to glass-ceramics at different times and temperatures for maximum ionic conduction achievement. The crystals were characterized by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), Differential Scanning Calorimetry (DSC) and Complex Impedance Spectroscopy (CIS) methods. The maximum lithium ion conductivity for glass-ceramic, 5.32 × 10 −3  S/cm at 26 °C was obtained for specimen crystallized at 850 °C for 8 h with minimum activation energy of 0.286 eV. Increasing the crystallization temperature results in secondary phase formation in grain boundary and increasing in crystallization time results in microcracks formation in specimen. Both phenomena decreased the ionic conductivity.