Silicic

Environmental chemistry

Oceanography

Analytical Chemistry (journal)

Optics

Volcano

Physics

Absorption (acoustics)

Geology

Engineering

Infrared spectroscopy

Composite material

Fourier transform infrared spectroscopy

Catalysis

Seismology

Organic chemistry

Chemistry

Absorption band

Metallurgy

Materials science

Mineralogy

Silicic acid

Silicate

Diatom

Sodium silicate

Biogenic silica

Chemical engineering

Silicon

Amorphous solid

Crystallography

Aluminosilicate

Scientific Reports

There is increased interest in the terrestrial silicon cycle in the last decades as its different compounds and species have large implications for ecosystem performance in terms of soil nutrient and water availability, ecosystem productivity as well as ecological aspects such as plant–microbe and plant-animal feedbacks. The currently existing analytical methods are limited. Fourier-transform infrared spectroscopy (FTIR) analysis is suggested being a promising tool to differentiate between the different Si species. We report here on the differentiation of varying Si-species/Si-binding (in synthetic material) using FTIR-analyses. Therefore, we collected FTIR-spectra of five different amorphous silica, Ca-silicate, sodium silicate (all particulate), a water-soluble fraction of amorphous silica and soil affected by volcanic activity and compared their spectra with existing data. A decrease of the internal order of the materials analyzed was indicated by peak broadening of the Si–O–Si absorption band. Peak shifts at this absorption band were induced by larger ions incorporated in the Si–O–Si network. Additionally, short-range ordered aluminosilicates (SROAS) have specific IR absorption bands such as the Si–O–Al band. Hence, SROAS and Si phases containing other ions can be distinguished from pure amorphous Si species using FTIR-analyses.

Comparing amorphous silica, short-range-ordered silicates and silicic acid species by FTIR