Abstract
Single-crystal Raman and infrared reflectivity data including high pressure results to over 200 kbar on a natural, probably fully ordered MgAl2O4 spinel reveal that many of the reported frequencies from spectra of synthetic spinels are affected by disorder at the cation sites. The spectra are interpreted in terms of factor group analysis and show that the high energy modes are due to the octahedral internal modes, in contrast to the behavior of silicate spinels, but in agreement with previous data based on isotopic and chemical cation substitutions and with new Raman data on gahnite (∼ ZnAl2O4) and new IR reflectivity data on both gahnite and hercynite (∼Fe0.58Mg0.42Al2O4). Therefore, aluminate spinels are inappropriate as elastic or thermodynamic analogs for silicate spinels.
Fluorescence sideband spectra yield complementary information on the vibrational modes and provide valuable information on the acoustic modes at high pressure. The transverse acoustic modes are nearly pressure independent, which is similar to the behavior of the shear modes previously measured by ultrasonic techniques. The pressure derivative of all acoustic modes become negative above 110 kbar, indicating a lattice instability, in agreement with previous predictions. This lattice instability lies at approximately the same pressure as the disproportionation of spinel to MgO and Al2O3 reported in high temperature, high pressure work.
Similar content being viewed by others
References
Andermann G, Caron A, Dows D (1965) Kramers-Kronig dispersion analysis of infrared reflectance bands. J Opt Soc Am 55:1210–1216
Boehler R, Chopelas A (1991) A new approach to laser heating in high pressure mineral physics. Geophys Res Lett 18:1147–1150
Brout R (1959) Sum rule for lattice vibrations in ionic crystals. Phys Rev 113:43–44
Burdick L, Anderson DL (1975) Interpretation of velocity profiles of the mantle. J Geophys Res 80:1070–1074
Chang ZP, Barsch GR (1973) Pressure dependence of single-crystal elastic constants and anharmonic properties of spinel. J Geophys Res 78:2418–2433
Chopelas A (1988a) Thermodynamic parameters of mantle minerals from optical spectra at high pressures 2nd Int'l Symposium on Experimental Mineralogy, Petrology, and Geochemistry, (abstract) Terra Cognita 8:59
Chopelas A (1988b) Second order phase transition in pyroxene? Implications for the upper mantle (abstract). Trans Am Geophys Union 69:472
Chopelas A (1990a) Thermal properties of solids at high pressures from vibrational spectroscopy: MgO and MgAl2O4. High Pressure Res 5:711–713
Chopelas A (1990b) Thermal expansion, heat capacity, and entropy of MgO at mantle pressures. Phys Chem Minerals 17:142–148
Chopelas A (1990c) Thermal properties of forsterite at mantle pressures derived from vibrational spectroscopy. Phys Chem Minerals 17:149–156
Chopelas A (1991) Thermal properties of β-spinel at mantle pressures derived from vibrational spectroscopy: Implications for the mantle at 400 km depth. J Geophys Res 96:11817–11829
Chopelas A, Boehler R (1984) MgO:V2+ pressure scale for diamond anvil cells. Material Res Soc Symp Proc 22:275–278
Chopelas A, Boehler R (1991) Raman spectroscopy of high pressure MgSiO3 phases synthesized in a CO2 laser heated diamond anvil cell: perovskite and clinopyroxene. Proc US-Japan Seminar, Ise, Japan, January 1991
Chopelas A, Nicol MF (1982) Pressure dependence to 100 kbar of the phonons of MgO at 90 and 295 K. J Geophys Res 94:8591–8597
Farmer VC, Lazarev AN (1974) Symmetry and crystal vibrations. In: Farmer VC (ed) The Infrared Spectra of Minerals Mineralogical Society is the publisher. London, pp 51–68
Fateley WG, McDevitt NT, Bently FF (1971) Infrared and Raman selection rules for lattice vibrations: the correlation method. Appl Spectrosc 25:155–174
Finger LW, Hazen RM, Yagi T (1979) Crystal structures and electron densities of nickel and iron silicate spinels at elevated temperature or pressure. Am Mineral 64:1002–1009
Finger LW, Hazen RM, Hofmeister AM (1986) High pressure crystal chemistry of spinel (MgAl2O4) and Magnetite (Fe3O4): comparisons of silicate spinels. Phys Chem Minerals 13:215–220
Fraas LM, Moore JE, Salzberg JB (1973) Raman characterization studies of synthetic and natural MgAl2O4 crystals. J Chem Phys 58:3585–3592
Gervais F, Piriou B (1974) Anharmonicity in several polar mode crystals: adjusting phonon self energy of LO and TO modes in Al2O3 and TiO2 to fit infrared reflectivity. J Phys C 7:2374–2386
Hofmeister AM (1987) Single-crystal absorption and reflection infrared spectroscopy of forsterite and fayalite. Phys Chem Minerals 14:499–513
Hofmeister AM (1991) Calculation of bulk modulus and its pressure derivative from vibrational frequencies and mode Grüneisen parameters: solids with cubic symmetry or one-nearest neighbor distance. J Geophys Res 96:16181–16203
Hofmeister AM, Chopelas A (1991) Vibrational spectroscopy of end member garnets. Phys Chem Minerals 17:503–526
Hofmeister AM, Mao HK, Bell PM (1986) Spectroscopic determination of thermodynamic properties of γ-Fe2SiO4 at mantle pressures (abstract). Trans Am Geophys Union 67:395
Hofmeister AM, Xu J, Mao H-K, Bell PM, Hoering TC (1989) Thermodynamics of Fe-Mg olivines at mantle pressures: Mid- and far-infrared spectroscopy at high pressure. Am Mineral 74:281–306
Irifune T (1986) An experimental investigation of the pyroxene-garnet transformation in a pyrolite composition and its bearing on the composition of the mantle. Phys Earth Planet Inter 45:324–336
Irifune T, Fujino K, Ohtani E (1991) Phase transitions in MgAl2O4 spinel at pressures up to 28 GPa. Proc of US-Japan Conf, Ise, Japan
Ishii M, Hiraishi J, Yamanaka T (1982) Structure and lattice vibrations of Mg -Al spinel solid solution. Phys Chem Minerals 8:64–68
Mao H-K, Xu J, Bell PM (1986) Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. J Geophys Res 91:4673–4676
McMillan PM, Hofmeister AM (1988) Infrared and Raman spectroscopy. In: Hawthorne FC (ed) Spectroscopic Methods in Mineralogy and Geology. Rev Mineral 18: 99–160
O'Horo MP, Frisillo AL, White WB (1973) Lattice vibrations of MgAl2O4 spinel. J Phys Chem Solids 34:23–28
Porto SPS, Krishnan RS (1967) Raman effect of corundum. J Chem Phys 47:1009–1012
Preudhomme J, Tarte P (1971) Infrared studies of spinels III. The normal II–III spinels. Spectrochim Acta 27A:1817–1835
Preudhomme J, Tarte P (1972) Infrared studies of spinels IV. Normal spinels with a high valency tetrahedral cation. Spectrochim Acta 28A:66–79
Rigden SM, Jackson I, Niesler H, Ringwood AE, Liebermann RC (1988) Pressure dependence of the elastic wave velocities for Mg2GeO4 spinel to 3 GPa. Geophys Res Lett 15:605–608
Ringwood AE, Reid AF (1969) High pressure transformation of spinels, 1. Earth Planet Sci Lett 5:245–250
Scott JF, Porto SPS (1967) Longitudinal and transverse optical lattice vibrations in quartz. Phys Rev 161:903–910
Spitzer WG, Miller RC, Kleinman DA, Howarth LE (1962) Far-infrared dielectric dispersion in BaTiO3, SrTiO3, and TiO2. Phys Rev 126:1710–1721
Suzuki I, Kumazawa M (1980) Anomalous thermal expansion in spinel MgAl2O4. A possibility for a second order phase transition? Phys Chem Minerals 5:279–284
Thompson P, Grimes NW (1978) Observation of low energy phonons in spinel. Solid State Commun 25:609–611
Wood DL, Imbusch GF, Macfarlane RM, Kisliuk P, Larkin DM (1968) Optical spectrum of Cr3+ ions in spinels. J Chem Phys 48:5255–5263
Wood BJ, Kirkpatrick RJ, Montez B (1986) Order-disorder phenomena in MgAl2O4 spinel. Am Mineral 71:999–1006
Wooten F (1972) Optical Properties of Solids. Academic Press, New York, p 260
Yamanaka T, Takeuchi Y, Tokonami M (1984) Anharmonic thermal vibrations of atoms in MgAl2O4 at temperatures up to 1933 K. Acta Crystallogr B40:96–102
Yoneda A (1990) Pressure derivatives of elastic constants of single crystal MgO and MgAl2O4. J Phys Earth 38:19–55
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Chopelas, A., Hofmeister, A.M. Vibrational spectroscopy of aluminate spinels at 1 atm and of MgAl2O4 to over 200 kbar. Phys Chem Minerals 18, 279–293 (1991). https://doi.org/10.1007/BF00200186
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00200186