Characterization and physical properties of Li 2O–CaF 2–P 2O 5 glass ceramics with Cr 2O 3 as a nucleating agent—Physical properties

Abstract

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 Li 2O–CaF 2–P 2O 5: Cr 2O 3 glass ceramics, have been reported. The optical absorption, ESR and magnetic susceptibility studies indicate that the chromium ions exist in Cr 5+, Cr 4+ and Cr 6+ states in addition to Cr 3+ state in these samples. The dielectric constant and loss variation with the concentration of Cr 2O 3 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.