Characterization and physical properties of Li2O–CaF2–P2O5 glass ceramics with Cr2O3 as a nucleating agent—Physical properties

In this paper, studies on various physical properties, viz., dielectric properties (dielectric constant, loss tan δ, a.c. conductivity σ) over a wide range of frequency and temperature, optical absorption, ESR at liquid nitrogen temperature and magnetic susceptibility at room temperature of Li2O–CaF2–P2O5: Cr2O3 glass ceramics, have been reported. The optical absorption, ESR and magnetic susceptibility studies indicate that the chromium ions exist in Cr5+, Cr4+ and Cr6+ states in addition to Cr3+ state in these samples. The dielectric constant and loss variation with the concentration of Cr2O3 have been explained on the basis of space charge polarization mechanism. The dielectric relaxation effects exhibited by these samples have been analysed by a graphical method and the spreading of dielectric relaxation has been established. The a.c. conductivity in the high-temperature region seems to be connected both with electronic and ionic movements.

The optical absorption spectroscopic studies on Li2O–CaF2–P2O5: Cr2O3 glass ceramics indicate that a part of Cr3+ ions oxidized into Cr6+ ions during the crystallization. These ions enter the glass network with CrO42- structural units, alternate with PO4 units and increase the rigidity of the glass-ceramic sample.Figure optionsDownload as PowerPoint slide