Assessment of MgHf4P6O24 Electroceramic Oxide Electrolyte in High-Temperature Electrochemical Sensor for Sensing Mg in Non-Ferrous Alloys

Abstract

In this paper, the electrochemical impedance analysis of MgHf4P6O24 electroceramic oxide electrolyte on platinised pellets of 13mm diameter (Ø) and 3.8mm thickness depicts the electrical properties of Mg 2+ -cation conducting species in the characterised solid-state electrolytes measured using the two-probe analysis at 182-764 o C, and from 100mHz to 32MHz, were evaluated. In this analysis, promising ionic conductivity of 4.52 x 10 -4 Scm -1 for MgHf4P6O24 electroceramic electrolyte was exhibited at 747 o C, thereby maintaining both materials and operational stability at 1000 o C ≤ T/ o C≤1300.In addition to this, the design, fabrication and testing of solid-state Mg-sensors using the electrochemical method have been achieved. The novel high-temperature Mg-sensors were designed using the highly conducting Mg 2+ -cation solid-state electrolyte by incorporating a biphasic powder mixture of MgCr2O4 + Cr2O3 as ceramic solid-state reference electrode in air, which has shown promising trend after successfully sensing the Mg dissolved in molten Al at 700±5 o C. A linear dependence of emf on logarithm of Mg concentration was achieved. The transport number, tmg2+ = 0.84±0.03 was achieved which indicates that the conducting specie in MgHf4P6O24 solid-state electrolyte is Mg 2+ -cation. The solid-state electrolyte has the potential for application in high-temperature electrochemical sensors and other devices.