Effect of high pressure on the infrared spectra of solid nitro- and nitrito-cobalt(iii) ammine complexes

1992 ◽  
Vol 96 (7) ◽  
pp. 931-937 ◽  
Author(s):  
E. V. Boldyreva ◽  
L. P. Burleva ◽  
E. B. Burgina ◽  
V. P. Baltachinov ◽  
H. Ahsbahs ◽  
...  
Keyword(s):  
High Pressure ◽  
Infrared Spectra ◽  
Ammine Complexes

Magmatic evolution of the Gaussberg lamproite (Antarctica): volatile content and glass composition

2004 ◽  
Vol 68 (1) ◽  
pp. 83-100 ◽  
Author(s):  
E. Salvioli-Mariani ◽  
L. Toscani ◽  
D. Bersani
Keyword(s):  
High Pressure ◽  
Infrared Spectra ◽  
Melt Inclusions ◽  
Glass Composition ◽  
Relative Increase ◽  
The Other ◽  
Residual Liquid ◽  
Volatile Content ◽  
Magmatic Evolution ◽  
Ultrapotassic Rock

AbstractThe lamproite of Gaussberg is an ultrapotassic rock where leucite, olivine and clinopyroxene microphenocrysts occur in a glass-rich groundmass, containing microliths of leucite, clinopyroxene, apatite, phlogopite and rare K-richterite.Abundant silicate melt inclusions occur in olivine, leucite and, rarely, in clinopyroxene microphenocrysts. Raman investigations on melt inclusions showed the presence of pure CO2 in the shrinkage bubbles. On the other hand, the glass of the groundmass is CO2-poor and contains up to 0.70 wt.% of dissolved H2O, as estimated by infrared spectra. It is inferred that CO2 was released at every stage of evolution of the lamproite magma (CO2-rich shrinkage bubbles), whereas H2O was retained for longer in the liquid. At Gaussberg, CO2 seems to have a major role at relatively high pressure where it favoured the crystallization of H2O-poor microphenocrysts; the uprise of the magma to the surface decreased the solubility of CO2 and caused a relative increase in water activity. As a consequence, phlogopite and K-richterite appeared in the groundmass.The glass composition of both the groundmass and melt inclusions suggests different evolutions for the residual liquids of the investigated samples. Sample G886 shows the typical evolution of a lamproite magma, where the residual liquid evolves toward peralkaline and Na-rich composition and crystallizes K-richterite in the latest stage. Sample G895 derives from mixing/mingling of different batches of magma; effectively glasses from melt inclusions in leucite and clinopyroxene are more alkaline than those found in early crystallized olivine. Leucite and clinopyroxene crystallized early from a relatively more alkaline batch of lamproite magma and, successively, a less alkaline, olivinebearing magma batch assimilated them during its rise to the surface.

First-Principles Study of Structural and Vibrational Properties of α-SiO2 under Pressure

2015 ◽  
Vol 775 ◽  
pp. 191-196
Author(s):  
Xiao Wei Lei ◽  
Yong Song ◽  
Kuo Yang ◽  
Hui Zhao
Keyword(s):  
High Pressure ◽  
Perturbation Theory ◽  
Infrared Spectra ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Vibrational Properties ◽  
Vibrational Modes ◽  
Density Functional Perturbation Theory ◽  
Good Agreement

Using first principles approach, we present the structural, vibrational and dielectric properties of α-SiO2. The calculations have been carried out within the density functional perturbation theory and linear response formalism using the norm-concerving pseudopotentials and a plane wave basis. All the vibrational modes identified are in good agreement with experiment. The calculated infrared spectra are also in good agreement with available experimental results both for the positions and the intensities of the main peaks. We find that the modes Eu7 and A2u4 splits in two respectively at high hydrostaticpressures. Then we calculate the infrared spectra under high pressure of different orientations. The vibrational modes in different phase transitions are reported and discussed respectively.

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