Concentration Dependent Spectroscopic Properties of Terbium Ion Doped Lead-Borate Glasses and Vitroceramics

Abstract

Terbium ions doped lead borate glasses and vitroceramics with the composition of xTb₄O₇·(100-x)[4PbO·B₂O₃] where x is from 0 to 25 mol % Tb₄O₇ were prepared by the use of a melt-quenching protocol. Their structural and spectroscopic properties were characterized by x-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman and ultraviolet-visible spectroscopies. The XRD patterns reveal the amorphous nature of the samples with low Tb₄O₇ content up to x equal to 1 mol % Tb₄O₇. Above this concentration, the analysis of XRD measurements indicates the presence of new crystaline phases in the vitroceramic samples. The FTIR and Raman measurements indicate that the addition of the rare earth oxides in the host network is realized by the deformation of the Pb-O-Pb or O-Pb-O angles, the formation of varied borate units and a large number of non-bridging oxygen atoms. The compositional evolution is conducted at the formation of crystalline phases of the terbium and lead atoms. The terbium atoms have a pronounced affinity toward the borate units while the lead atoms are attracted toward the oxygen atoms. Structural investigations by ultraviolet-visible spectroscopy show the presence of larger bands due to the f-f electron transitions of the Tb³⁺ ions and 6 s² → 6s 6p transitions of Pb²⁺ ions, respectively. The optical gap energy values are dependent upon the concentration of the dopant level.

Keywords:

• Glasses
• lead-borate
• optical properties
• terbium ions

Additional information

Funding

The financial support of this work was provided by the PN-III-P1-1.1-PD-2016, No. 33/2018.