title: A vibrational spectroscopic study of perhamite, an unusual silico-phosphate.
abstract: The silico-phosphate mineral perhamite has been studied using a combination of electron and vibrational spectroscopy. SEM photomicrographs reveal that perhamite morphology consists of very thin intergrown platelets that can form a variety of habits. Infrared spectroscopy in the hydroxyl-stretching region shows a number of overlapping bands which are observed in the range 3581-3078 cm(-1). These wavenumbers enable an estimation to be made of the hydrogen bond distances in perhamite: 3.176(0), 2.880(5), 2.779(6), 2.749(3), 2.668(1) and 2.599(7)A. Intense Raman bands are observed in the region 1110-1130 and 966-996 cm(-1) and are assigned to the SiO(4) and PO(4) symmetric stretching modes. Other bands are observed in the range 1005-1096 cm(-1) and are attributed to the nu(3) antisymmetric bending modes of PO(4). Some low intensity bands around 874 cm(-1) were discovered and remain unclassified. Bands in the low-wavenumber region are assigned to the nu(4) and nu(2) out-of-plane bending modes of the OSiO and PO(4) units. Raman spectroscopy is a useful tool in determining the vibrational spectroscopy of mixed hydrated multi-anion minerals such as perhamite. Information on such a mineral would be difficult to obtain by other means.
authors.affiliation: Inorganic Materials Research Program, School of Physical and Chemical Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia. r.frost@qut.edu.au
authors.forename: Ray L
authors.initials: RL
authors.lastname: Frost
authors.forename: Matt L
authors.initials: ML
authors.lastname: Weier
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Mills
mesh_terms: D018360:Crystallography, X-Ray; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000032:analysis* / Q000737:chemistry; D008956:Models, Chemical; D010710:Phosphates / Q000032:analysis* / Q000737:chemistry; D017640:Silicates / Q000032:analysis* / Q000737:chemistry; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014867:Water / Q000737:chemistry
chemical_list: D008903:Minerals; D010710:Phosphates; D017640:Silicates; D014867:Water