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 Mg2+-cation conducting species in the characterised solid-state electrolytes measured using the two-probe analysis at 182-764oC, 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 747oC, thereby maintaining both materials and operational stability at 1000oC ≤ T/oC≤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 Mg2+-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±5oC. 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 Mg2+-cation. The solid-state electrolyte has the potential for application in high-temperature electrochemical sensors and other devices.
The long term stability of the titanium/hydrogen system as the solid reference electrode in high-temperature proton conductor-based hydrogen sensors
