Comparison of Raman spectra in characterizing gibbsite, bayerite, diaspore and boehmite

Abstract

High-quality Raman spectra were used for the characterization of alumina phases of gibbsite, bayerite, diaspore and boehmite. The Raman spectrum of gibbsite shows four strong, sharp bands at 3617, 3522, 3433 and 3364 cm −1 in the hydroxyl stretching region. The spectrum of bayerite shows seven bands at 3664, 3652, 3552, 3542, 3450, 3438 and 3420 cm −1 . Five broad bands at 3445, 3363, 3226, 3119 and 2936 cm −1 and four broad and weak bands at 3371, 3220, 3085 and 2989 cm −1 are present in the Raman spectrum of the hydroxyl stretching region of diaspore and boehmite. The hydroxyl stretching bands are related to the surface structure of the minerals. The Raman spectra of bayerite, gibbsite and diaspore are complex whereas the Raman spectrum of boehmite shows only four bands in the low-wavenumber region. These bands are assigned to deformation and translational modes of the alumina phases. A comparison of the Raman spectrum of bauxite with those of boehmite and gibbsite showed the possibility of using Raman spectroscopy for on-line processing of bauxites that contain a mixture of alumina phases.

Ambient‐Condition nano‐Alumina Formation Through Molecular Control

“…Raman spectrum reveals peaks at 550 and 1100cm Ϫ1 . This is markedly different from other crystalline or hydrated aluminas [33].…”

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

“…All four main forms of alumina hydroxides/oxyhydroxides have been detected, namely, bayerite {α-Al(OH)3} and gibbsite {γ-Al(OH)3}, diaspore {α-AlOOH}, and boehmite {γ-AlOOH}. A differentiation between the various forms of alumina hydrates, as well as cobalt oxides/hydroxides on the basis of the observed peak wavenumbers and relevant literature [39,67,[69][70][71][72][73][74][75][76][77], is attempted in Table 6. Three main types of Raman spectra are observed in Figure 11: (i) Spectra with predominance of bands corresponding to aluminum hydroxides/oxyhydroxides, where bands ascribed to characteristic vibrations of Co-O-Co bonds also present accountable intensity (7Co_2, 7Co_3, 20Co_1, 20Co_3).…”

Microstructural Properties of Natural Allophane/Gibbsite from a White Bauxite Deposit in Montenegro

“…[13] The interlayer hydrogen-bonded OH groups oriented along the c-axis of gibbsite crystals showed bands at 3433, 3370 and 3363 cm -1 , whereas the interlayer hydrogen-bonded OH groups oriented nearly parallel to the (001) plane showed IR bands at 3623, 3526 and 3519 cm -1 . Typical Raman bands of gibbsite [14,15] were positioned at 3617, 3522, 3433 and 3364 cm -1 . In the present work the shoulders in the FT-IR spectrum ( Figure 3a) were noticed at 3620, 3530, 3460 and 3380 cm -1 and these IR positions can be assigned to the gibbsite phase.…”