Glasses with ferroelectric phases

Glasses ceramics, with ferroelectric phases embedded in the glass matrix, were prepared by the melt-quenching through heat-treatments (HT) of silicate, borate and phosphate glasses. Some glasses were heat-treated with the application of an external electric field (TET). The structure and morphology of the samples were studied by X-ray powder diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The dielectric properties, in function of frequency and temperature, were studied and discussed through a three serial of a resistance in parallel with a constant phase element (CPE), two related with the sample surfaces and one with the bulk material, showing that the bulk has the major contribution for the dielectrical characteristics. The temperature dependence of the dc electrical conductivity (σdc), the thermally stimulated depolarization current (TSDC), and the ac conductivity (σac), measured at 1 kHz, were used to characterize the samples. The structure, the dielectric properties and the electrical conductivity reflect the important role carried out by the base glass the heat-treatment and the electric field during the HT and the ferroelectric phases in the properties of glass-ceramics.