Dielectric properties of LiF-B2O3 glasses doped with certain rare earth ions

Dielectric constant epsilon, loss tan delta and a.c. conductivity sigma of LiF-B2O3: Ln(3+) (where Ln = Ce, Pr Nd and Tb) glasses are studied as functions of frequency tin the range 10(2)-10(6) Hz) and temperature (range 30-200 degrees C). The dielectric breakdown strength of these glasses was also determined at room temperature in an air medium. The rate of increase of epsilon and tan delta with temperature decreases with decrease in the ionic radius of RE3+ ion whereas the dielectric breakdown strength, the activation energy for a.c. conduction in the high temperature region decreases with increase in the ionic radius of RE3+ ion. An attempt has been made to explain the a.c. conduction in these glasses on the basis of quantum mechanical tunnelling (QMT) model.