title: Far-infrared spectroscopy of alumina phases.
abstract: Far-infrared spectroscopy (FIR) has been used to distinguish alumina phases boehmite, diaspore, gibbsite and bayerite. The pellets of samples were prepared by mixing alumina phases with polyethylene at a ratio of 1:50, and the spectra were recorded between 50 and 400 cm(-1). The spectrum of boehmite resembles that of diaspore in the 300-400 cm(-1) region. Boehmite has two characteristic FIR bands at 366 and 323 cm(-1), while diaspore has five at 354, 331, 250, 199 and 158 cm(-1). The spectrum of gibbsite resembles that of bayerite in the 230-300 cm(-1) region. Gibbsite shows three characteristic FIR bands at 371, 279 and 246 cm(-1), whereas bayerite shows six at 383, 345, 326, 296, 252 and 62 cm(-1). The overlapping bands were resolved, and the spectra were manipulated appropriately using band analysis techniques. The FIR spectra are in harmony with the FT-Raman spectra. Far-infrared spectroscopy allows the study and differentiation of the stretching of AlO4 units to characterize these four alumina phases. Far-IR spectroscopy complements the mid-IR and near-IR for distinguishing alumina phases in bauxites.
authors.affiliation: Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, Brisbane, Australia. h.ruan@qut.edu.au
authors.forename: H D
authors.initials: HD
authors.lastname: Ruan
authors.forename: R L
authors.initials: RL
authors.lastname: Frost
authors.forename: J T
authors.initials: JT
authors.lastname: Kloprogge
authors.forename: L
authors.initials: L
authors.lastname: Duong
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; D000537:Aluminum Oxide