Enhanced thermal stability and crystallization of nonlinear optical RExBi2-xZnB2O7 in RE2O3-added bismuth zinc borate glasses (RE: Eu, Gd, Er)

Abstract The effect of the substitution of RE2O3 (5 mol%) (RE: Eu, Gd, Er) for Bi2O3 on the thermal stability and crystallization behavior in 33.3Bi2O3-33.3ZnO-33.3B2O3 glass with a low temperature melting feature was clarified to explore new potentials of Bi2O3-based glasses and glass-ceramics. Both the glass transition and crystallization temperatures increased with the RE2O3 addition and the thermal stability against crystallization was enhanced. This is due to the increase in the average chemical bond strength of the glasses with the addition of RE2O3. The formation of RE3+-doped nonlinear optical RExBi2-xZnB2O7 crystals was confirmed from X-ray diffraction analyses and photoluminescence spectra in the glass crystallization. RE2O3 oxides added to the glass do not act as nucleating agents for the crystallization of Bi2ZnB2O7. The photoluminescence related to the 4f-4f transitions of Eu3+ and Er3+ was clearly observed even in the glasses with a relatively large amount (33.3 mol%) of B2O3, suggesting that RE3+ ions are present in the environment of Bi2O3-rich region with low phonon energies.