Role of pyrite during the thermal degradation of kerogen using in situ high-temperature ESR technique

1991 ◽  
Vol 5 (3) ◽  
pp. 441-444 ◽  
Author(s):  
Mohammed Y. Bakr ◽  
T. Yokono ◽  
Y. Sanada ◽  
M. Akiyama
Keyword(s):  
High Temperature ◽  
Thermal Degradation

scholarly journals First In-Situ Measurements of Plume Chemistry at Mount Garet Volcano, Island of Gaua (Vanuatu)

2020 ◽  
Vol 10 (20) ◽  
pp. 7293
Author(s):  
Joao Lages ◽  
Yves Moussallam ◽  
Philipson Bani ◽  
Nial Peters ◽  
Alessandro Aiuppa ◽  
...  
Keyword(s):  
High Temperature ◽  
Emission Rates ◽  
Gas Composition ◽  
Gas Analyzer ◽  
Total Volatile ◽  
Volcanic Gas ◽  
So2 Flux ◽  
Gas Chemistry

Recent volcanic gas compilations have urged the need to expand in-situ plume measurements to poorly studied, remote volcanic regions. Despite being recognized as one of the main volcanic epicenters on the planet, the Vanuatu arc remains poorly characterized for its subaerial emissions and their chemical imprints. Here, we report on the first plume chemistry data for Mount Garet, on the island of Gaua, one of the few persistent volatile emitters along the Vanuatu arc. Data were collected with a multi-component gas analyzer system (multi-GAS) during a field campaign in December 2018. The average volcanic gas chemistry is characterized by mean molar CO2/SO2, H2O/SO2, H2S/SO2 and H2/SO2 ratios of 0.87, 47.2, 0.13 and 0.01, respectively. Molar proportions in the gas plume are estimated at 95.9 ± 11.6, 1.8 ± 0.5, 2.0 ± 0.01, 0.26 ± 0.02 and 0.06 ± 0.01, for H2O, CO2, SO2, H2S and H2. Using the satellite-based 10-year (2005–2015) averaged SO2 flux of ~434 t d−1 for Mt. Garet, we estimate a total volatile output of about 6482 t d−1 (CO2 ~259 t d−1; H2O ~5758 t d−1; H2S ~30 t d−1; H2 ~0.5 t d−1). This may be representative of a quiescent, yet persistent degassing period at Mt. Garet; whilst, as indicated by SO2 flux reports for the 2009–2010 unrest, emissions can be much higher during eruptive episodes. Our estimated emission rates and gas composition for Mount Garet provide insightful information on volcanic gas signatures in the northernmost part of the Vanuatu Arc Segment. The apparent CO2-poor signature of high-temperature plume degassing at Mount Garet raises questions on the nature of sediments being subducted in this region of the arc and the possible role of the slab as the source of subaerial CO2. In order to better address the dynamics of along-arc volatile recycling, more volcanic gas surveys are needed focusing on northern Vanuatu volcanoes.

Role of oxygen on YBaCuO solidification as seen from high-temperature in-situ susceptibility measurements

1994 ◽  
Vol 235-240 ◽  
pp. 433-434 ◽  
Author(s):  
X. Chaud ◽  
E. Beaugnon ◽  
P. de Rango ◽  
F. Ducloux ◽  
R. Tournier ◽  
...  
Keyword(s):  
High Temperature

Regeneration of high-silica zeolites after sulfamethoxazole antibiotic adsorption: a combined in situ high-temperature synchrotron X-ray powder diffraction and thermal degradation study

2014 ◽  
Vol 78 (5) ◽  
pp. 1141-1159 ◽  
Author(s):  
L. Leardini ◽  
A. Martucci ◽  
I. Braschi ◽  
S. Blasioli ◽  
S. Quartieri
Keyword(s):  
High Temperature ◽  
Thermal Degradation ◽  
Powder Diffraction ◽  
Thermal Regeneration ◽  
Desorption Process ◽  
Degradation Study ◽  
X Ray ◽  
Cell Parameters ◽  
High Silica

AbstractThe thermal regeneration of sulfamethoxazole (SMX)-loaded Y and ZSM-5 zeolites was studied using a combined in situ high-temperature synchrotron X-ray powder diffraction and thermal degradation study. The evolution of the structural features was monitored in real time in the 30–575°C temperature range by full-profile Rietveld analysis. SMX thermal degradation pathways into high-silica zeolite antibiotic adducts, as well as the release of evolved species are similar to those for pure SMX. The adsorption/desorption process occurs without any significant loss of zeolite crystallinity, though slight deformations to the channel apertures are observed. Regenerated zeolites regain almost perfectly ‘bare’ (i.e. unloaded) material unit-cell parameters and only a slight memory effect, in terms of structural deformations induced by the process, is registered in the channel geometry. Interestingly, these changes do not affect the adsorption properties of the regenerated samples, which are able to re-adsorb comparable amounts of antibiotic molecules as in the first adsorption cycle.

The role of phlogopite in the deep Earth’s water and fluorine cycles

2020 ◽  
Author(s):  
Jiaqi Sun ◽  
Yan Yang ◽  
Qunke Xia
Keyword(s):  
Raman Spectroscopy ◽  
High Temperature ◽  
Powder Diffraction ◽  
Experimental Studies ◽  
Accessory Mineral ◽  
X Ray ◽  
Deep Earth ◽  
The Stability

<p>    Knowledge of the volatiles cycles is vital to understand the evolution of the planet Earth and the life it supports. Although it is gradually accepted that water and other volatiles are recycled into the mantle through subduction, it is still not unclear how these volatiles are transported down into the deep Earth. Phlogopite is an accessory mineral frequently observed in samples from the upper mantle, thereby acting as an important carrier of fluorine and water down to >200 km depth. Previous experimental studies and textural relationships of natural samples have indicated that fluorine-rich phlogopite can be stable under ultra-high-temperature conditions. To further investigate effects of fluorine on the stability of phlogopite, here, we present an atomic level research of effects of fluorine on the structural stability using in situ high temperature infrared spectroscopy, Raman spectroscopy, and X-ray powder diffraction. Both X-ray powder diffraction and Raman spectroscopy suggests that fluorine-poor phlogopite decomposes earlier than the fluorine-rich phlogopite. Moreover, the O-H bonds and lattice modes are stiffer for the fluorine-rich phlogopite than the fluorine-poor phlogopite, which is well responsible for the mechanism of fluorine stabilizing phlogopite. Based on our studies, we propose that fluorine-rich phlogopite can effectively transport water and fluorine to the deep Earth.</p>

The reaction of amorphous Ni-Nb films with Si in the presence of a native SiO2 layer

1990 ◽  
Vol 48 (4) ◽  
pp. 664-665
Author(s):  
N. Rozhanski ◽  
A. Barg
Keyword(s):  
High Temperature ◽  
Crystallization Temperature ◽  
Diffusion Barriers ◽  
Sio2 Layer ◽  
Si Substrate ◽  
Cross Sectional ◽  
Plan View ◽  
Temperature Range ◽  
Sputter Deposited

Amorphous Ni-Nb alloys are of potential interest as diffusion barriers for high temperature metallization for VLSI. In the present work amorphous Ni-Nb films were sputter deposited on Si(100) and their interaction with a substrate was studied in the temperature range (200-700)°C. The crystallization of films was observed on the plan-view specimens heated in-situ in Philips-400ST microscope. Cross-sectional objects were prepared to study the structure of interfaces.The crystallization temperature of Ni5 0 Ni5 0 and Ni8 0 Nb2 0 films was found to be equal to 675°C and 525°C correspondingly. The crystallization of Ni5 0 Ni5 0 films is followed by the formation of Ni6Nb7 and Ni3Nb nucleus. Ni8 0Nb2 0 films crystallise with the formation of Ni and Ni3Nb crystals. No interaction of both films with Si substrate was observed on plan-view specimens up to 700°C, that is due to the barrier action of the native SiO2 layer.

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