P-02 Borate and silicate glasses doped with Ce3+ and Mn2+ ions for UV-VIS spectral shifting

Topic: Advanced glasses, ceramics and polymeric materials and nano materials

J. Volf^1*, P. Vařák¹, J. Cajzl ¹, P. Nekvindová ¹

¹ University of Chemistry and Technology, Prague, Technická 5, 166 28, Praha 6, Czechia

^* E-mail: jakub.volf@vscht.cz

Keywords: photoluminescence, silicate, borate, glass, cerium, manganese

Abstract: This study is aimed to investigate the possibilities of spectral shifting of light radiation by using the combination of Ce³⁺ and Mn²⁺ ions in glasses. We focused on the possibility of shifting the radiation from green region of spectra (470-550 nm) to red (650-730 nm) or blue (370-450 nm) regions. The combination of Ce³⁺ and Mn³⁺ ions has been shown to manifest this kind of shifting in special types of crystalline matrices [1-3], however it is yet to be investigated in glasses. The type of used matrix and method of preparation can influence the oxidation state of doped ions and their photoluminescence properties (shape and position of emission spectra, photoluminescence lifetime). The use of glasses also has several benefits over crystals in practical applications such as low cost and easy preparation.

To study the influence of glass matrix on photoluminescence, we prepared several types of glasses doped by mixture of Ce³⁺ and Mn²⁺ ions. First, two glasses with completely different matrices – silicate and borate – were prepared to study their suitability as host matrix for both ions. In addition, a set of borosilicate glasses with varying contents of SiO₂ and B₂O₃ were prepared and reducing agents were added to the batch to preserve cerium and manganese in +III and +II oxidation state, respectively. The glasses were prepared by a standard melt-quenching technique. Basic optical and physical properties of the glasses were measured, such as refractive index by m-line spectroscopy, density by pycnometric measurement and glass transition temperature by differential scanning calorimetry. Structure of the glasses was studied by Raman spectroscopy. XPS and EPR measurements were carried out to study the oxidation state of doped elements in the glass. Spectroscopic properties were evaluated by absorption spectroscopy and photoluminescence measurements in UV-VIS.

The results indicate that borate and borosilicate glasses are suitable hosts for incorporation of Ce³⁺ and Mn²⁺ ions, which results in 650 nm luminescence under UV excitation. However, pure borate glass displayed poor chemical resistance against water. Silicate glasses were chemically stable, but failed to manifest clear luminescence of Mn²⁺ ions in the region of 650 nm. Borosilicate glasses were prepared to combine the advantages of both types of glasses and the best ratio of B₂O₃/SiO₂ content was studied. Reducing agents were found to preserve Mn²⁺ ions in the glass and therefore enhance Mn²⁺ photoluminescence. The studied glasses are promising candidates for the use in photobioreactors for enhancing a growth of various bio-organisms such as algae.

References

[1] L. Wondraczek, et al., Nat. Commun. (2013) 2047. https://doi.org/10.1038/ncomms3047.

[2] B. G. You, et al., Journal of Luminescence (2012) 2433–2438. https://doi.org/10.1016/j.jlumin.2012.04.018.

[3] C. Safi, et al., Renewable and Sustainable Energy Reviews (2014) 265–278. https://doi.org/10.1016/j.rser.2014.04.007.

Acknowledgments

This work was supported from the grant of MSMT No 21-SVV/2020.