A. Sergio Bezerra Sombra

Crystallization of ferroelectric LiNbO3 in niobophosphate glasses

Niobophosphate glasses [(xNb2O5(0.5 − x)P2O5)0.5Li2O]: yFe2O3 were prepared by the melt-quenching method and analysed by means of infrared spectroscopy and x-ray powder diffraction. LiNbO3 crystals were detected for high niobium contents samples. The use of both techniques gives new information about the structure of niobium-phosphate glasses and glass-ceramics.

Nonlinear switching in semiconductor (CdSSe) doped glass

Abstract Optical nonlinear switching due to increasing absorption has been observed in a nondegenerate pump and probe experiment in Semiconductor (CdSSe) Doped Glass (SDG). With the proper choice of the parameters, like modulation frequency and light intensity, one hundred percent modulation in a probe laser induced by a strong pump laser was obtained at room temperature. Two nonlinear regimes were observed, with saturated pump absorption being dominant at high pump power.

Thermally stimulated depolarization current and Mössbauer spectroscopy of iron-doped niobophosphate glasses

Niobophosphate glasses (P2O5-PbO-Nb2O5-K2O-XFe2O3), were studied using thermally stimulated depolarization currents and Mössbauer spectroscopy in samples of different iron concentrations, and were subjected to oxidation and reduction processes. The use of both techniques provided new information about the distribution of iron and niobium between tetrahedral and octahedral sites.

Electrical properties of LiKSO4 crystals at low temperatures

Abstract An overview of the dielectric and pyroelectric properties of LiKSO4 (LKS) from 4 K to 300 K is presented. The pyroelectric coefficient and the dielectric constant shows anomalous behavior associated with phase transitions occuring in the crystal. Comparing the pyroelectric coefficient as measured parallel and perpendicular to the “z” axis, we conclude that the new phase below 20 K belongs to the spatial group C1s or C2s.