Ultraviolet/visible reflection spectroscopy of molten and glassy silicates (MeOn–CaO–SiO2) and phosphates (MeOn–CaO–P2O5), Men+=Fe3+, Mn2+

Zebger, Ingo; Pfeifer, Frank; Nowack, Norbert

doi:10.1016/j.jnoncrysol.2005.09.003

Cited by 10 publications

(19 citation statements)

References 29 publications

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“…To calculate the geometric albedo of a planet with a combination of lava and quenched glass on the surface, we surveyed non-crystalline solids literature for specular reflectance values from molten silicates as a proxy for specular reflectance values for lava. Specular reflection values from molten silicates were measured at an incidence angle of 0°and had an average reflectance of 0.15 for compositions with major oxide proportions most similar to our basalt quenched glass sample's composition (Zebger et al 2005). The planet geometric albedo was calculated by varying the amounts of lava and quenched glass on the surface according to…”

Section: Modelmentioning

confidence: 99%

Low-albedo Surfaces of Lava Worlds

Essack

Seager

Pajusalu

2020

ApJ

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Hot super-Earths are exoplanets with short orbital periods (<10 days), heated by their host stars to temperatures high enough for their rocky surfaces to become molten. A few hot super-Earths exhibit high geometric albedos (>0.4) in the Kepler band (420-900 nm). We are motivated to determine whether reflection from molten lava and quenched glasses (a product of rapidly cooled lava) on the surfaces of hot super-Earths contribute to the observationally inferred high geometric albedos. We experimentally measure reflection from rough-and smoothtextured quenched glasses of both basalt and feldspar melts. For lava reflectance values, we use specular reflectance values of molten silicates from non-crystalline solids literature. Integrating the empirical glass reflectance function and non-crystalline solids reflectance values over the dayside surface of the exoplanet at secondary eclipse yields an upper limit for the albedo of a lava-quenched glass planet surface of ∼0.1. We conclude that lava planets with solid (quenched glass) or liquid (lava) surfaces have low albedos. The high albedos of some hot super-Earths are most likely explained by atmospheres with reflective clouds (or, for a narrow range of parameter space, possibly Ca/Al oxide melt surfaces). Lava planet candidates in TESS data can be identified for follow-up observations and future characterization.

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Section: Modelmentioning

confidence: 99%

Low-albedo Surfaces of Lava Worlds

Essack

Seager

Pajusalu

2020

ApJ

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“…Even though there have been several studies on the physicochemical properties of the CaO-SiO2-MnO slag due to its importance in smelting and refining processes for the production of manganese ferro-alloys as well as high manganese steel grades, [39][40][41][42][43][44][45] the systematic and fundamental approach on the structure of this slag system is scarcely found. Zebger et al 46) proposed from the ultraviolet reflectivity of the molten and glassy states of the CaO-SiO2-MnO system that the tetrahedral MnO4-complex is formed in liquid state. Jung et al 47) measured the relative content of three types of oxygens such as bridging (O 0 ), nonbridging (O -), and free oxygen (O 2-) in the CaO-SiO2-MnO system by Xray photoelectron spectroscopy (XPS) and found that the silicate melts were depolymerized by addition of MnO at a fixed CaO/SiO2 ratio.…”

Section: Introductionmentioning

confidence: 99%

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Park

2012

ISIJ Int.

109

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The quantitative structural information such as the relative abundance of silicate discrete anions (Q n units) and the concentration of three types of oxygens, viz. free-, bridging-and nonbridging oxygen can be obtained from micro-Raman spectra of the quenched CaO-SiO2-MnO glass samples. Various transport properties such as viscosity, density, and electrical conductivity can be expected as a simple linear function of 'ln (Q 3 /Q 2 ),' indicating that these thermophysical properties are strongly dependent on a degree of polymerization of silicate melts in the composition of silica content greater than about 30 mol%. The present methodology is believed to be widely extended to various slag systems in ferrous and non-ferrous metallurgical communities.KEY WORDS: silicate structure; Raman spectroscopy; viscosity; density; conductivity; Q 3 /Q 2 ratio; degree of polymerization.

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“…The position of the bands in the absorption spectra and the one in the reflection spectra do not coincide but the discrepancy is very small. This has been shown in [10]. Differences between absorption and reflection spectra can only be observed concerning the height of the bands.…”

Section: Base and Evaluation Of Uvnis-reflection Spectrummentioning

confidence: 85%

“…Fe As a consequence of thermal movements of the complexes at higher temperatures, fuzzy bond distances, disharmonious oscillations and fluctuations arise [9][10][11][12][13][14][15][16][17]. The asymmetric composition of the complexes (involving terminal and non-permanent OZ-ions of the network as ligands) causes dipole moments of the complexes that are non-equal to zero.…”

Section: Complexmentioning

confidence: 99%

“…In glasses, the coordination number at room temperature is an important parameter for a description of the chemical bond whereas, in liquid systems, thermal dissociation equilibria of coordinative bonds (complexes) dominate. Due to the strong thermal fluctuations, the bond distances become fuzzy and the measurements provide only average coordination numbers [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. These results are based on the application of methods from optical spectroscopy [7][8][9][10]17], X-ray and neutron diffraction [11][12][13][14][15][16]20] and NMR and XAFS-spectroscopy [19,21] on liquid silicates, borates and aluminates.…”

Section: Introductionmentioning

confidence: 99%

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Application of UV/VIS‐Reflection Spectroscopy for Determination of the Oxidation State of Liquid Slags with High Fe³⁺‐Contents

Nowack

Zebger

Pfeifer

et al. 2007

steel research international

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This work considers the reflectivity of liquid oxides (silicates and phosphates) in the ultraviolet and visible spectral range using a reflection angle of 0°. We have developed a spectroscopic reflection method (impulse‐flash‐technique) and have investigated CaO‐FeOn‐SiO2 and CaO‐FeOn‐P2O5 with Fe2O3‐contents above 32 mol‐% (FeO1.5) at a temperature of 1400°C applying oxygen partial pressures of po2 = 0.001 bar up to po2 = 0.21 bar. The increased reflectivity in the ultraviolet spectral range is based on the very intensive electron transfer (charge transfer bands, CT) from the oxide ion (bound to the respective matrix) to the Fe3+‐ion. The increased reflectivities in the visible spectral range are due to d‐d‐transitions in the Fe3+‐ion located in Fe3+‐O2− ‐complexes. This can be proven in the following way. The reflection bands in the visible range are much less pronounced than the CT‐bands in the UV range. In the slag melts, complexes with the coordination number 4, Fe3+(O2−)4, have been found predominantly. The relation between the redox state of liquid slags and their UV‐reflectance has been evaluated quantitatively. The basic investigations for recording the redox state of liquid silicates and phosphates during a running metallurgic process are part of this work. Liquid silicates and phosphates are the most important slag systems in this context.

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Ultraviolet/visible reflection spectroscopy of molten and glassy silicates (MeOn–CaO–SiO2) and phosphates (MeOn–CaO–P2O5), Men+=Fe3+, Mn2+

Cited by 10 publications

References 29 publications

Low-albedo Surfaces of Lava Worlds

Low-albedo Surfaces of Lava Worlds

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Application of UV/VIS‐Reflection Spectroscopy for Determination of the Oxidation State of Liquid Slags with High Fe³⁺‐Contents

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Ultraviolet/visible reflection spectroscopy of molten and glassy silicates (MeOn–CaO–SiO2) and phosphates (MeOn–CaO–P2O5), Men+=Fe3+, Mn2+

Cited by 10 publications

References 29 publications

Low-albedo Surfaces of Lava Worlds

Low-albedo Surfaces of Lava Worlds

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Application of UV/VIS‐Reflection Spectroscopy for Determination of the Oxidation State of Liquid Slags with High Fe3+‐Contents

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Application of UV/VIS‐Reflection Spectroscopy for Determination of the Oxidation State of Liquid Slags with High Fe³⁺‐Contents