A transparent glass with the composition 60B2O3–30Li2O–10Nb2O5 (mol%) was prepared by the meltquenching
technique. Glass–ceramics, containing LiNbO3 ferroelectric crystallites, were obtained by
heat-treatment (HT) above 500 C, with and without the presence of an external electric field. The dielectric
properties of the glass and glass–ceramic were investigated, as a function of temperature (270–
315 K), in the 10 mHz–32 MHz frequency range. The presence of an external electric field, during the
heating process, improves the formation of LiNbO3 crystallites. The rise of the treatment temperature
and the applied field, during the heat-treatment, leads to a decrease in the dc electric conductivity
(rdc), indicating a decrease of the charge carriers number. The dielectric permittivity (e0) values
(300 K;1 kHz) are between 16.25 and 18.83, with the exception of the 550 C HT sample that presents
a e0 value of 11.25. An electric equivalent circuit composed by an R in parallel with a CPE element was
used to adjust the dielectric data. The results reflect the important role carried out by the heat-treatment
and the electric field during the HT in the electric properties of glass–ceramics.