The elaboration of Na+ super-ionic conductor (NaSICON) ceramics is studied in this work. These solid electrolytes can be used as sensor for detection
of polluted gases in air. Two sorts of ceramics with different chemical compositions are synthesised by soft chemistry route:
a zirconium-based NaSICON and a hafnium-based NaSICON. DTA-TG and temperature depending X-ray diffractometry were used to
follow the thermal decomposition of the precursor phases. The electrical properties of these ceramic sodium ionic conductors
are investigated by complex impedance spectroscopy (CIS). The substitution of the zirconium by the hafnium increases the ceramic
conductivity and decreases the activation energy Ea (from 0.29 to 0.12 eV).
Authors:C. Marhag, H. Said, P. Satre, C. Favotto, and J. Rogez
Study of solid-liquid phase diagram of LiPO3-Pb(PO3)2 binary system, in certain calcination conditions, shows the existence of several metastable phasis. When heated at a temperature
of 723 K the binary mixtures lead uncompletely to a defined compound Pb2Li(PO3). On heating these ternary solid mixtures, three eutectic reactions have been observed: LiPO3+Pb(PO3)2→Liquid at a temperature of 793 K(1) LiPO3+Pb2Li(PO3)5→Liquid at a temperature of 843 K (2) Pb2Li(PO3)5+Pb(PO3)2→Liquid at a temperature of 891 K (3) The metastable liquid phase appears in the system at temperature of 793 K. DTA experiments
performed on the binary LiPO3-Pb(PO3)2 mixtures, show a superposition of two diagrams. The first one is metastable and the second represents the stable equilibrium
phase diagram. Measurements of liquid enthalpy of binary LiPO3-Pb(PO3)2 system at temperature of 979.65 K were reported. The corresponding values were very small and so the binary system can be
considered as athermal. Assuming an ideal behaviour, the liquidus curves in the metastable diagram were calculated and the
eutectic reaction (LiPO3-Pb(PO3)2→Liquid) was confirmed at 793 K.
Authors:M. Mansori, C. Favotto, K. Jardet, M. Roubin, A. Sebaoun, and P. Satre
The oxygen exchange between the condensed phase(s) and the gas phase was studied as a function of temperature for superconducting
phases of the system (Bi,Pb)-Sr-Ca-Cu-O.
An oxygen probe apparatus allowed confirmation that the variation in oxygen composition in the Pb2212 and Pb2223 superconducting
phases is a reversible phenomenon on heating and cooling. It was demonstrated that the mass loss of both phases, for the 905
and 980°C isotherms, was due to the oxygen composition variation and to PbO loss (this latter phenomenon begin irreversible).
Authors:M. Hichri, C. Favotto, H. Zamali, Y. Feutelais, B. Legendre, A. Sebaoun, and M. Jemal
Phase diagram of the binary system AgNO3—RbNO3 was studied using thermal analysis technique, differential scanning calorimetry and X-ray diffraction. This binary exhibits a congruently melting compound Ag0.5Rb0.5NO3 (m. p.=138°C), an incongruently melting one Ag0.33Rb0.66NO3 with two polymorphic varieties, two eutectics at (36 mol% RbNO3, 128°C) and at (60 mol% RbNO3, near 134°C) respectively and a peritectic at (60.5 mol% RbNO3, 141°C). This system contains also three invariant reactions at 164, 222 and 282°C due to the phase transitions of RbNO3 and another one at
164°C due to the phase transition of AgNO3.