Improved Ionic Conductivity of MgM₄P₆O₂₄ (M = Hf, Zr) Ceramic Solid-State Electrolytes by Sol-Gel Synthesis

Abstract

Data from electrochemical impedance measurement of MgHf4P6O24 and MgZr4P6O24 solid-state electrolytes show significant improvement in the ionic conductivity of the ceramic electrolytes. The electrical behaviour of MgHf4P6O24 and MgZr4P6O24 solidstate electrolytes were measured using two-probe analysis at a temperature range of 182 -764 o C, and at a frequency within 100 mHz to 32 MHz range. In this analysis, promising bulk ionic conductivity of 4.52 x 10 -4 Scm -1 and 7.23 x 10 -3 Scm -1 were achieved for MgHf4P6O24 and MgZr4P6O24 electrolytes, respectively, at impedance maximum temperatures of 747 o C and 725 o C, respectively. The sol-gel method was deployed in the synthesis of MgHf4P6O24 and MgZr4P6O24 nanoparticles electrolytes. The thermogravimetric analysis -differential scanning calorimetry (TGA-DSC), and X-ray diffraction (XRD) were characterisation techniques deployed in this study to determine and evaluate the phase composition structure of the nanoparticles calcined at 900 o C and the sample pellets sintered at 1300 o C.

Assessment of Novel MgCe4P6O24 Ceramic Electrolyte in Fabricating Mg-Sensors: Focus on Structure and Electrochemical Impedance Spectroscopy

“…Materials research focused on the sol-gel synthesis and characterisation of structural and electrical properties of the tetravalent B-site oxides has experienced a resurgence of interest in recent years. In particular, tetravalent Zr and Hf ion based ceramic electrolytes have attracted so much attention in the past few years due to their excellent applicability potentials as high-temperature electroceramics in chemical sensors, solid-oxide fuel cells, solid-state batteries and other high-temperature systems (1)(2)(3)(4). The potential application of novel functional materials, such as ceramic electrolytes in sensor fabrication, rechargeable energy sources and storage systems for future vehicles like solid-state multivalent batteries is the signature need for increasing future demands which has culminated in this study of monoclinic MgCe4P6O24 ceramic electrolyte.…”

“…In using appropriate stoichiometric amount of precursor oxides, the most studied representatives of MgZr4(1-x)M4xP6O24 family are MgZr4P6O24 [x = 0] (1,2,4) and MgHf4P6O24 [x = 1, M = Hf] (3,4), with these ceramic electrolytes showing excellent improvements in both the ionic conductivity and thermodynamic stability, which are suitable parameters for identifying the ceramic electrolytes as a divalent Mg ion conductor in fabricating solid-state Mg-sensors (1)(2)(3)(4). In this study however, novel MgCe4P6O24 ceramic electrolyte was synthesised using sol-gel method and characterised to analyse the structure and electrical properties of the ceramic electrolyte.…”