Advanced Sensor and Detection Materials

Abstract

NASICON (Na-Super-Ioni-CONductor) has the general formula Na1-xZr2 P3- x Six O12 (0 ≤ x ≤3) and is derived from the parent compound sodium zirconium phosphate, NaZr2 (PO4 )3 , i.e., NZP. It belongs to the class of superionic conduc tors, materials that have high ionic conductivity at elevated or room temperatures, similar to those of liquid electrolytes at room temperatures. NASICON is special due to its unique structural features (three-dimensional), which confer on it high conductivity and diverse physical and chemical characteristics suitable for various applications in many fi elds. Th e Na, Zr and P can be substitutted by atoms of dif fering sizes and oxidation states, up to about forty or more of such atoms, leading to its tailorability for targetted applications in recahargeable lithium ion batter ies, gas sensors, low-zero-and even negative thermal expansion materials, nuclear waste immobilization, among others. In the present work we survey some classes of ionic conductors and the theoretical models of their conduction. A review of the electrical conductivity, dielectric relaxation, methods of synthesis, together with characterization techniques of NASICON, DTA/TGA, Impedance spectros copy, NMR, FT-IR, among others, are highlighted. Case studies of some experi mental results have been presented.