Phase transition and impedance spectroscopy analysis of Pb-5(Cr1-xAlx)(3)F-19 ceramics

Analysis of the a.c. conductivity data of Pb5Al3F19 within the complex perm ittivity formalism allowed, in a previous work, to show a new transition at 670 K corresponding most probably to the expected, but hitherto unobserved , transition from the paraelastic phase II to the paraelectric prototype ph ase I of Pb5Al3F19 A new investigation of Pb-5(Cr0.1Al0.9)(3)F-19 confirms this and allows us to complete the phase diagram of the Pb-5(Cr1-xAlx)(3)F- 19 solid solution system for (0.80 less than or equal to x less than or equ al to 1) in the high-temperature range. Ceramics with compositions correspo nding to x = 0 and 0.5 were also characterized by this type of spectroscopy impedance method.