XPS and FT-IR investigation of silicate polymers

Abstract

This article presents the results of an investigation of the compositional and structural features of an inorganic polymer synthesized from amorphous silica and KOH. The inorganic polymers were characterized using Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). FT-IR investigation of the inorganic polymers showed that an increase in the hydroxide concentration used in the synthesis shifts the position of the maximum absorbance of Si-O bands toward lower wave numbers, indicating the transformation of Q 4 units to Q 3 and Q 2 units. XPS investigation of the inorganic polymers showed that the total amount of oxygen and potassium present in the sample increased when higher concentrations of hydroxide were used in the synthesis. The O/Si ratio of the inorganic polymers changed from 2 to 2.6 when the KOH concentration was increased from 0.75 to 4 M. The increase in the O/Si ratio can be explained by the greater dissolution of SiO 2 particles leading to the formation of branched polymers and gelation.

Modification of niobium surfaces using plasma electrolytic oxidation in silicate solutions

“…This conclusion is also corroborated by analysis of the O 1s spectrum (Fig. 9), where the most intense component can be assigned to siloxane type bonding (Si-O-Si) typical for silica [53,55]. A small number of other oxygen species are attributed to the oxygen-metal bonding in silicates (component A), water (part of component B), and siloxanol and organic compounds (C).…”

“…Additionally, the Si 2p core excitation (Fig. 8) shows two components assigned to silicate (A) and crystalline silica (B) where component B predominates [52][53][54][55]. In the XPS technique, most of the intensity, i.e.…”

Gold nanoparticles developed in sol–gel derived apatite—bioactive glass composites

“…The component at 533.7 eV (36.3%) for the sample treated at 110°C can be assigned to oxygen in Si-O-Si bonds [39,40]. For the sample treated at 300°C, there is a slight shift of the observed binding energy to a higher value, while the relative concentration increased to 60.7%.…”

Effect of Dissolved Silica on Immobilization of Boron by Magnesium Oxide

“…This is likely due to the fact that the reaction times in the experiments here were shorter (only up to 28 days) than those of the previous studies (3 months-2 years), causing the Si-O-Si units to be too little developed to be detected by FT-IR. The IR spectra of the solid samples in the solutions with silica after 1, 2, and 5 days (Figure 6b) show a large broad band at~1100 cm −1 , suggesting the presence of amorphous silica as the band at~1100 cm −1 was assigned to the Si-O stretching of Q4 units [17]. After 17 days, the band weakened and shifted to~1050 cm −1 , corresponding to Q3 units with one non-binding oxygen (Si-O-NBO) [17], indicating the transformation of amorphous silica into layer structured M-S-H.…”

“…The IR spectra of the solid samples in the solutions with silica after 1, 2, and 5 days (Figure 6b) show a large broad band at~1100 cm −1 , suggesting the presence of amorphous silica as the band at~1100 cm −1 was assigned to the Si-O stretching of Q4 units [17]. After 17 days, the band weakened and shifted to~1050 cm −1 , corresponding to Q3 units with one non-binding oxygen (Si-O-NBO) [17], indicating the transformation of amorphous silica into layer structured M-S-H. This means that the formation of M-S-H would have completed between 5 and 17 days, and this is the reason it took~17 days for the boron sorption ratio to reach the steady state.…”