Vibrational spectroscopy and density of K₂O–B₂O₃–GeO₂ glasses with variable B/Ge ratio

Abstract

Glasses of the K2O–B2O3–GeO2 system were studied by means of Raman and IR spectroscopy.

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“…For these reasons, it was necessary to identify the contributions of the individual vibrational modes by deconvolution, involving the fitting of Gaussian peaks in different frequency regions of the spectra. Such Gaussian deconvolution has been described in previous spectroscopic studies of germanate, borate, and borogermanate glasses 8,20,25,[30][31][32][33][34][35][36] .…”

“…Peak 4 was assigned to symmetrical stretching vibrations of Ge-O-Ge bonds in 3-membered GeO4 rings 35,37 . Between 500 and 600 cm -1 , peaks 5 and 6 could be attributed to vibrations of Ge-O-Ge bonds in three-membered GeO4 and symmetrical vibrations of Ge-O-Ge [35][36][37] . The presence of only Ge 4+ in borogermanate glasses was recently elucidated using Ge K-edge EXAFS and XANES measurements 8,20 .…”

“…Peaks 9 (815 cm -1 ) and 10 (828 cm -1 ) could be attributed to symmetrical stretching vibrations of Ge-Oin Q 2 and Q 3 species, respectively 36,38 . In addition, peak 11 (~908 cm -1 ) was assigned to diborate groups 36 .…”

“…Previous investigations of germanate and borogermanate glasses using Raman spectroscopy found that the region between 800 and 900 cm -1 was dominated by vibrational modes of Q 2 and Q 3 units derived from the breakdown of tetrahedral [GeO4] units 31,32,[35][36][37] . Peaks 9 (815 cm -1 ) and 10 (828 cm -1 ) could be attributed to symmetrical stretching vibrations of Ge-Oin Q 2 and Q 3 species, respectively 36,38 . In addition, peak 11 (~908 cm -1 ) was assigned to diborate groups 36 .…”

“…At higher frequencies (above 1050 cm -1 ), there was a predominance of vibrations of borate groups ( Figure 5(c)). The Raman spectrum for the BGB-0Tb glass presented a band at 1200 cm -1 (peak 12), assigned to diborate groups, and a broad band at around 1427 cm -1 with overlapping peaks assigned to asymmetric stretching of B-O bonds of BO3/2 units (peak 13, at 1337 cm -1 ), stretching vibration of BO3/2ring (peak 14, at 1427 cm -1 ), and vibrations related to non-bridging oxygen atoms of B-Obonds (peak 15, at 1495 cm -1 ) 36 .…”