Glass composition and excitation wavelength dependence of the luminescence of Eu3+ doped lead borate glass

This work explores the relationship between the bandwidth of luminescence spectral features and their relative intensities, using glasses doped with europium, Eu3+, over a wide composition range. Glasses of composition (B2O3)(70)(PbO)(29)(0.5Eu(2)O(3))(1) and (B2O3)(z)(PbO)(99.6-z)(0.5Eu(2)O(3))(0.4), (z = 20, 30, 40, 60, 70), were prepared by the melting-quenching technique. Variable-wavelength measurements by the prism-coupling method enabled interpolation of refractive index at selected wavelengths. Diffuse reflectance spectra confirmed the incorporation of Eu3+ into the glass, and scanning electron microscopy displayed that this was in a homogeneous manner. Vibrational spectra showed a change in boron coordination from BO3 to BO4 units with increase of PbO content in the glass. Multi-wavelength excited luminescence spectra were recorded for the glasses at temperatures down to 10 K and qualitative interpretations of spectral differences with change of B2O3 content are given. The quantitative analysis of D-5(0) luminescence intensity-bandwidth relations showed that although samples with higher boron content closely exhibit a simple proportional relationship with band intensity ratios, as expected from theory, the expression needs to be slightly modified for those with low boron content. The Judd-Ofelt intensity analysis of the D-5(0) emission spectra under laser excitations at low temperature gives Omega(2) values within the range from (3.9-6.5) x 10(-20) cm(2), and Omega(4) in the range from (4.1-7.0) x 10(-20) cm(2), for different values of z. However, no clear monotonic relation was found between the parameter values and composition. The Judd-Ofelt parameters are compared with those from other systems doped with Eu3+ and are found to lie in the normal ranges for Eu3+-doped glasses. The comparison of parameter values derived from the 10 K spectra with those from room temperature spectra for our glasses, which are fairly constant for different compositions, shows that site selection occurs at low temperature. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3620985]