Colossal dielectric and magnetodielectric effect in Er2O3 nanoparticles embedded in a SiO2 glass matrix

An intriguing colossal enhancement of dielectric constant along with magnetodielectric (MD) behavior is observed in nanoparticle (NP) Er2O3 (0.5 mol %) embedded SiO2 glass matrix synthesized via sol-gel route. A broad dielectric peak with a maximum at T-m (similar to 270 K) exhibits typical diffuse phase transition following modified Curie-Weiss behavior. Conduction mechanism (showing energy barrier E-a similar to 1.13 eV near T-m) is closely related to the thermally activated oxygen vacancies. At the highest applied magnetic field 9 T, the dielectric constant around T-m is enhanced almost similar to 2.75 (at 2.5 kHz frequency) times compared with that at zero field. The MD effect observed in this glassy composite is considered to be associated with the direct consequence of magnetoresistance changes which depends on the magnetic NP size and separation.