title: Vibrational spectroscopic study of the nitrate containing hydrotalcite mbobomkulite.
abstract: Raman spectroscopy has been used to study the nitrate hydrotalcite mbobomkulite NiAl2(OH)16(NO3).4H2O. Mbobomkulite along with hydrombobomkulite and sveite are known as 'cave' minerals as these hydrotalcites are only found in caves. Two types of nitrate anion are observed using Raman spectroscopy namely free or non-hydrogen bonded nitrate and nitrate hydrogen bonded to the interlayer water and to the 'brucite-like' hydroxyl surface. Two bands are observed in the Raman spectrum of Ni-mbobomkulite at 3576 and 3647 cm(-1) with an intensity ratio of 3.36/7.37 and are attributed to the Ni3OH and Al3OH stretching vibrations. The observation of multiple water stretching vibrations implies that there are different types of water present in the hydrotalcite structure. Such types of water would result from different hydrogen bond structures.
authors.affiliation: Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, G.P.O. Box 2434, Brisbane Queensland 4001, Australia. r.frost@qut.edu.au
authors.forename: Ray L
authors.initials: RL
authors.lastname: Frost
authors.forename: Kristy L
authors.initials: KL
authors.lastname: Erickson
authors.forename: Theo J
authors.initials: TJ
authors.lastname: Kloprogge
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D006860:Hydrogen Bonding; D008276:Magnesium Hydroxide / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: D008903:Minerals; D009566:Nitrates; C010467:hydrotalcite; D000536:Aluminum Hydroxide; D003300:Copper; D009532:Nickel; D008276:Magnesium Hydroxide