The crystallization phenomenon on a modified phosphate glass interpreted through the correlation between the a.c. electrical behaviour and the non isothermal nucleation

•Lithium phosphate glass to a vitro-ceramic by homogeneous nucleation.•Structural changes detection using impedance spectroscopy correlated to DSC scan.•Polarization behaviour as evidence of the crystalline structures birth in a glassy matrix.•Devitrification phenomenon using a Gaussian approximation with the elements of M. Avrami’s theory.