Ramanspektroskopische Untersuchungen an festen und in Wasser gelösten Polyboraten / Investigations of Solid Polyborates and their Aqueous Solutions by Raman Spectroscopy

Abstract

Abstract Raman spectra of solid H3BO3, Na2[B4O5(OH)4] · 8 H2O, K[B5O6(OH)4] · 2H2O and Na[B(OH)4] were recorded between 300 and 1500 cm-1 as well as of borax in aqueous solutions as a function of concentration and pH. Because of better solubility in water, the Raman spectrum of ammonium tetraborate in aqueous solution was also recorded as a function of pH. For comparisons the Raman spectra of solid (NH4)2[B4O5(OH)4] · 2 H2O, β-NH4[B5O6(OH)4] · 2 H2O, NH4[B5O6(OH)4] · 0,67 H2O and NH4[B5O6(OH)4] were considered. In solution, all lines in the Raman spectra could be assigned and the degree of depolarization measured. The assigned Raman frequencies can be used for the identification of unknown B-O-lines and therefore of unknown borate or polyborate structures.