Luminescence and dielectric properties of nano-structured Eu3+:K2O–Nb2O5–SiO2 glass-ceramics

In the present study, results concerning luminescence and dielectric properties of Eu2O3 (0.5 wt% in excess) doped nano-crystallized KNbO3 containing transparent glass-ceramics obtained from glass of composition 25K2O–25Nb2O5–50SiO2 (mol%) by varied heat-treatment duration at 800 °C have been analyzed and reported. The formed crystallization phase, crystallite size and morphology have been examined through XRD, FESEM, TEM and FTIRRS measurements. The observed steep increase in the dielectric constant (ɛ) of glass-ceramics over the as-prepared glass is attributed to the formation of ferroelectric nano-crystalline KNbO3 in glass matrix. The absorption spectra of all the samples have revealed the characteristic 4f–4f intraband absorption transitions of Eu3+ ions. The measured photoluminescence spectra have exhibited emission transitions 5D0, 1 → 7Fj (j = 0, 1, 2, 3 and 4) of Eu3+ ions. The excited level lifetimes have been determined from measured fluorescence decay curves. The rare earth ion site symmetry (nearly Cv) has been understood based on the nature of the Stark splittings of emission bands detected in both Eu3+: glass and Eu3+: glass-ceramics.

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