title: The Garfield and Uley nontronites--an infrared spectroscopic comparison.
abstract: FTIR and Infrared emission spectroscopy (IES) has been used to characterise the Uley (Australian) and Garfield nontronites. These clay minerals are characterised by a strong emission band at 3570 cm(-1) attributed to the FeFeOH unit. Dehydroxylation is followed by the loss of intensity of this band as a function of temperature. Dehydroxylation is also followed by the loss of intensity of the FeFeOH deformation vibration at 843 cm(-1). IES shows that the dehydroxylation occurs as a continuous process in comparison to DTA/TGA studies where the dehydroxylation occurs abruptly at 425 degrees C. Water in these high iron bearing smectites have been observed through the stretching mode at 3430 cm(-1) and the bending mode at 1630 cm(-1). Different types of water are identified in the nontronite structure by the analysis of the band profile in the 1590-1680 cm(-1) region. Low frequency vibrations show that the Uley green nontronite is similar to the Garfield nontronite. The brown Uley nontronite is closer to the Hohen-Hagen nontronite. The Uley nontronites may, therefore, be used spectroscopically to replace other nontronites as a reference clay mineral.
authors.affiliation: Centre for Instrumental and Developmental Chemistry, Queensland University of Technology, Brisbane, Australia. r.frost@qut.edu.au
authors.forename: Ray L
authors.initials: RL
authors.lastname: Frost
authors.forename: J Theo
authors.initials: JT
authors.lastname: Kloprogge
authors.forename: Zhe
authors.initials: Z
authors.lastname: Ding
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry; D000077215:Clay; D005765:Gastrointestinal Agents / Q000737:chemistry; D017640:Silicates; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000538:Aluminum Silicates; D005765:Gastrointestinal Agents; D017640:Silicates; D001546:Bentonite; C033214:Smectite; D000077215:Clay