Thermodynamics of strontium tungstate evaporation

Kazenas, E. K.; Tsvetkov, Yu. V.; Astakhova, G. K.; Samoilova, I. O.; Volchenkova, V. A.

doi:10.1134/s0036029507020036

Cited by 11 publications

(7 citation statements)

References 2 publications

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“…At high temperatures, the relative elemental abundances in the system play a larger role in determining the vapor composition, so that silicon (the most abundant element in the system after oxygen) will dominate the vapor as SiO, followed by O 2 , O, and the moderately volatile Mg-and Fe-bearing gases, which typically comprise 1%-10% of the vapor (e.g., Fe-oxides in the melt dissociate into Fe, FeO, O, and O 2 in the vapor; Kazenas & Tagirov 1995). The temperature of the transition between a SiO-dominated regime and a Na-and/or oxygen fugacity as a function of temperature.…”

Section: Chemical Speciation Of Saturated Silicate Vapormentioning

confidence: 99%

Chemistry of Impact-Generated Silicate Melt-Vapor Debris Disks

Visscher

Fegley

2013

ApJ

107

112

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In the giant impact theory for lunar origin, the Moon forms from material ejected by the impact into an Earth-orbiting disk. Here we report the initial results from a silicate melt-vapor equilibrium chemistry model for such impact-generated planetary debris disks. In order to simulate the chemical behavior of a two-phase (melt+vapor) disk, we calculate the temperature-dependent pressure and chemical composition of vapor in equilibrium with molten silicate from 2000 to 4000 K. We consider the elements O, Na, K, Fe, Si, Mg, Ca, Al, Ti, and Zn for a range of bulk silicate compositions (Earth, Moon, Mars, eucrite parent body, angrites, and ureilites). In general, the disk atmosphere is dominated by Na, Zn, and O 2 at lower temperatures (< 3000 K) and SiO, O 2 , and O at higher temperatures. The high-temperature chemistry is consistent for any silicate melt composition, and we thus expect abundant SiO, O 2 , and O to be a common feature of hot, impact-generated debris disks. In addition, the saturated silicate vapor is highly oxidizing, with oxygen fugacity (f O 2 ) values (and hence H 2 O/H 2 and CO 2 /CO ratios) several orders of magnitude higher than those in a solar-composition gas. High f O2 values in the disk atmosphere are found for any silicate composition because oxygen is the most abundant element in rock. We thus expect high oxygen fugacity to be a ubiquitous feature of any silicate melt-vapor disk produced via collisions between rocky planets.

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Section: Chemical Speciation Of Saturated Silicate Vapormentioning

confidence: 99%

Chemistry of Impact-Generated Silicate Melt-Vapor Debris Disks

Visscher

Fegley

2013

ApJ

107

112

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“…It is well known [13] that alkali metal polyphosphates have a relatively low melting temperature and high vapor pressure on heating. This has made it possible to suggest that sodium polyphosphate may be used as a component for combined technological action.…”

Section: Introductionmentioning

confidence: 99%

Porous Ceramic Based on Calcium Pyrophosphate

et al. 2015

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Porous ceramic, whose composition is mainly represented by calcium b-pyrophosphate b-Ca 2 P 2 O 7 , is prepared from a porous mixture containing synthetic calcium g-pyrophosphate g-Ca 2 P 2 O 7 and milled 1-aqueous sodium dihydrophosphate in an amount from 2.5 to 40 wt.%. Ceramic sintering proceeds by a liquid-phase sintering mechanism due to melt formation in the system Na 2 O-CaO-P 2 O 5 . Ceramic microstructure after firing in the range 800 -1000°C makes it possible to consider sodium polyphosphate not only as a component facilitating sintering by a liquid-phase mechanism, but also as an inorganic pore-forming agent.

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“…•10 -9 ;~2•10 -7 ;~3•10 -6 ,~4•10 -5 ;~2.6•10 -3 and~8.5•10 -2 Pa at temperatures, K: 1700, 1800, 1900, 2000, 2200 and 2400, 2.6•10 -3~8 .5•10 -2 respectively [4]. The vapor pressure, observed above used oxides, is as follows [5]. At 300 K (practically corresponding to the optimum temperature for the synthesis of titanium carbide), vapor pressure of titanium oxide (TiO2) reaches~1 Pa; at 2000 K (nearly corresponding to the optimum temperature for the synthesis of titanium diboride), it is equal to~0.01 Pa.…”

Section: Resultsmentioning

confidence: 99%

Carbothermal and boron carbide reduction of oxides of some transition metals

et al. 2021

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The study presents a possible mechanism to produce carbides and diborides of transition metals, such as titanium, vanadium, chromium and zirconium. The carbothermal synthesis of transition metal carbides has defined the direct dependence between the thermodynamic stability of oxides and the temperature range of the reduction onset (the stronger the oxide, the higher the value of the temperature is). It reaches 2000-2100, 1500-1600, 1300-1400 and 2100-2200°C for such carbides as TiC, VC0,88, Cr3C2 and ZrC respectively. The same dependence has not been found for the diborides of these metals. Optimum synthesis temperatures for all these compounds lie in the range of 1600-1700 °C. This viable method to produce transition metal carbides consists in the transfer of vaporous higher and lower oxides. Diborides preparation involves the transfer of oxides and boron vapors onto the surface of the carbon material with the subsequent chemical interaction. In the case of carbide-boron reduction of zirconium oxide in excess of boron carbide, the reaction product will be a composite material (B4C – ZrB2). The ceramics based on this composite possesses high performance properties.

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Thermodynamics of strontium tungstate evaporation

Cited by 11 publications

References 2 publications

Chemistry of Impact-Generated Silicate Melt-Vapor Debris Disks

Chemistry of Impact-Generated Silicate Melt-Vapor Debris Disks

Porous Ceramic Based on Calcium Pyrophosphate

Carbothermal and boron carbide reduction of oxides of some transition metals

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