Préparation et étude des propriétés de conduction ionique des polyphosphate mixtes de type M$^{\rm I}$M$^{\rm III}$(PO$_3$)$_4$, (M$^{\rm I}$ = Li, K et M$^{\rm III}$ = Y, Bi)

Abstract

The field of research related to ionic transport in the solid electrolytes has passed through very fast evolution during the last years. The main importance here has the discovery of many ionic conducting compounds which are characterized by the nature of the ion responsible for the ionic transport, by the temperature range, and the dimensionality of the conducting phase. The materials with high ionic conductivity have various applications in the energetics, the analysis and the electronics fields. In particular, the compounds with Li$^+$ cations are of a great interest in connection with production of electrochemical generators of high energy density. Nevertheless the study of materials with low ionic conductivity remains interesting to specify some mechanisms of transport. Within the confines of the systematic study of a new long chain polyphosphates containing monovalent and yttrium cations, appearing in the M$^{\rm I}$PO$_3$ – M$^{\rm III}$(PO$_3$)$_3$ systems with (M$^{\rm I}$ = Li, K and M$^{\rm III}$ = Y). We have described the chemical preparations and the structural studies of these mixed polyphosphates of type M$^{\rm I}$M$^{\rm III}$(PO$_3$)$_4$ with (M$^{\rm I}$ = Li, K and M$^{\rm III}$ = Y). These incongruent melting compounds were identifie by X-ray diffraction and the infra-red spectroscopy. Both these two intermediate compounds and the LiBi(PO$_3$)$_4$ polyphosphate were the subject of the ionic study of conductivity with use of the impedance spectroscopy. The values of ionic conductivity as well as the energies of activation were given at various temperatures