scholarly journals The System K2CO3–CaCO3–MgCO3 at 3 GPa: Implications for Carbonatite Melt Compositions in the Shallow Continental Lithosphere

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 296 ◽  
Author(s):  
Anton V. Arefiev ◽  
Anton Shatskiy ◽  
Ivan V. Podborodnikov ◽  
Altyna Bekhtenova ◽  
Konstantin D. Litasov
Keyword(s):  
Solid Solutions ◽  
Temperature Stability ◽  
Thermal Conditions ◽  
Intermediate Compound ◽  
Phase Reaction ◽  
Continental Lithosphere ◽  
Liquid Fractionation ◽  
Solid Phases ◽  
Ternary Peritectic Reaction ◽  
Carbonate Melt

Potassic dolomitic melts are believed to be responsible for the metasomatic alteration of the shallow continental lithosphere. However, the temperature stability and range of compositions of these melts are poorly understood. In this regard, we performed experiments on phase relationships in the system K2CO3–CaCO3–MgCO3 at 3 GPa and at 750–1100 °C. At 750 and 800 °C, the system has five intermediate compounds: Dolomite, Ca0.8Mg0.2CO3 Ca-dolomite, K2(Ca≥0.84Mg≤0.16)2(CO3)3, K2(Ca≥0.70Mg≤0.30)(CO3)2 bütschliite, and K2(Mg≥0.78Ca≤0.22)(CO3)2. At 850 °C, an additional intermediate compound, K2(Ca≥0.96Mg≤0.04)3CO3)4, appears. The K2Mg(CO3)2 compound disappears near 900 °C via incongruent melting, to produce magnesite and a liquid. K2Ca(CO3)2 bütschliite melts incongruently at 1000 °C to produce K2Ca2(CO3)3 and a liquid. K2Ca2(CO3)3 and K2Ca3(CO3)4 remain stable in the whole studied temperature range. The liquidus projection of the studied ternary system is divided into nine regions representing equilibrium between the liquid and one of the primary solid phases, including magnesite, dolomite, Ca-dolomite, calcite-dolomite solid solutions, K2Ca3(CO3)4, K2Ca2(CO3)3, K2Ca(CO3)2 bütschliite, K2Mg(CO3)2, and K2CO3 solid solutions containing up to 24 mol % CaCO3 and less than 2 mol % MgCO3. The system has six ternary peritectic reaction points and one minimum on the liquidus at 825 ± 25 °C and 53K2CO3∙47Ca0.4Mg0.6CO3. The minimum point resembles a eutectic controlled by a four-phase reaction, by which, on cooling, the liquid transforms into three solid phases: K2(Mg0.78Ca0.22)(CO3)2, K2(Ca0.70Mg0.30)(CO3)2 bütschliite, and a K1.70Ca0.23Mg0.07CO3 solid solution. Since, at 3 GPa, the system has a single eutectic, there is no thermal barrier for liquid fractionation from alkali-poor toward K-rich dolomitic compositions, more alkaline than bütschliite. Based on the present results we suggest that the K–Ca–Mg carbonate melt containing ~45 mol % K2CO3 with a ratio Ca/(Ca + Mg) = 0.3–0.4 is thermodynamically stable at thermal conditions of the continental lithosphere (~850 °C), and at a depth of 100 km.

Liquid immiscibility and the origin of alkali-poor carbonatites

1988 ◽  
Vol 52 (364) ◽  
pp. 43-55 ◽  
Author(s):  
B. A. Kjarsgaard ◽  
D. L. Hamilton
Keyword(s):  
Liquid Immiscibility ◽  
Raw Material ◽  
Coarse Grained ◽  
Rock Types ◽  
Liquid Fractionation ◽  
Ring Complexes ◽  
The Common ◽  
Melt Cooling ◽  
Carbonate Melt ◽  
Common Sequence

AbstractThe work on liquid immiscibility in carbonate-silicate systems of Freestone and Hamilton (1980) has been extended to include alkali-poor and alkali-free compositions. Immiscibility is shown to occur on the joins albite-calcite and anorthite-calcite at 5 kbar. These results make it possible to interpret ocellar structure between calcite-rich spheroids in lamproite or kimberlite host rock as products of liquid immiscibility. The common sequence of rock types found in carbonatite complexes of melilitite-ijolite-urtite-phonolite is interpreted as being the result of both fractional crystallization and liquid fractionation, the corresponding carbonatite composition changing from nearly pure CaCO3 (±MgCO3) progressively to natrocarbonate. A carbonate melt cooling in isolation will suffer crystal fractionation, the residual liquid producing the rarer ferrocarbonatites, etc., whilst the crystal accumulate of calcite (dolomite) plus other phases such as magnetite, apatite, baryte, pyrochlore, etc., are the raw material for the coarse-grained intrusive carbonatites commonly found in ring complexes.

Selectivity in the Photoproduct Ratios from Norrish II Reactions of a Homologous Series of 2-Alkanones in Their Melt and Solid Phases. Comparison with Other Environments

1993 ◽  
Vol 58 (1) ◽  
pp. 142-152 ◽  
Author(s):  
Richard G. Weiss ◽  
Sosale Chandrasekhar ◽  
Patricia M. Vilalta
Keyword(s):  
Solid Solutions ◽  
Homologous Series ◽  
Size And Shape ◽  
Solid Phases ◽  
Solvent Molecules

The product ratios from Norrish II reactions of 2-tridecanone, 2-tetradecanone, 2-pentadecanone, 2-hexadecanone, 2-heptadecanone, and 2-nonadecanone have been measured at low percents of conversion in the melt and solid phases. Although elimination/cyclization photoproduct ratios from the neat crystals are > 60 in optimal cases, the ratios of cyclobutanol diastereomers (cyclization products) remain near those observed from melt irradiations. From comparisons of the photoproduct selectivities in the neat solids and in their solid solutions, where the solvent molecules are similar in size and shape to the 2-alkanones, it is concluded that the crystalline lattices of some foreign hosts offer environments to the pre-product biradical intermediates, which are at least as restrictive as the environments of the solid 2-alkanones.

scholarly journals Relationship between tolerance factor and temperature coefficient of permittivity of temperature-stable high permittivity BaTiO3–Bi(Me)O3 compounds

2016 ◽  
Vol 06 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Natthaphon Raengthon ◽  
Connor McCue ◽  
David P. Cann
Keyword(s):  
Temperature Coefficient ◽  
Solid Solutions ◽  
Temperature Stability ◽  
Past Research ◽  
Tolerance Factor ◽  
Microwave Dielectrics ◽  
High Permittivity ◽  
The Relationship

The temperature coefficient of permittivity ([Formula: see text]) of BaTiO3–Bi(Me)O3 solid solutions were investigated. It was determined that as the tolerance factor was decreased with the addition of Bi(Me)O3, the [Formula: see text] shifted from large negative values to [Formula: see text] values approaching zero. It is proposed that the different bonding nature of the dopant cation affects the magnitude and temperature stability of the permittivity. This study suggests that the relationship between tolerance factor and [Formula: see text] can be used as a guide to design new dielectric compounds exhibiting temperature-stable high permittivity characteristics, which is similar to past research on perovskite and pyrochlore-based microwave dielectrics.

Dielectric property of NBT@BT–BZN composite ceramics

2019 ◽  
Vol 33 (10) ◽  
pp. 1950115
Author(s):  
Aizhen Song ◽  
Yunkai Lv ◽  
Linlin Liang ◽  
Ruifang Wu ◽  
Jing Wang ◽  
...  
Keyword(s):  
Dielectric Property ◽  
Solid Phase ◽  
Temperature Stability ◽  
Composite Ceramic ◽  
Ceramic Materials ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Dense Microstructure ◽  
Temperature Change Rate ◽  
Structure Morphology

[Formula: see text] (NBT@BT–BZN) composite ceramic materials were prepared by wet solid-phase reaction method. The effects of [Formula: see text] (NBT) on the phase structure, morphology and dielectric properties of NBT@BT–BZN composites were studied in detail. All of the NBT@BT–BZN composites consist of BT–BZN and NBT phases. The dense microstructure was observed in all the NBT@BT–BZN samples. It is found that the introduction of NBT into BT–BZN leads to enhanced temperature stability in dielectric property. Samples with 40 mol.% NBT shows good dielectric property, in which the temperature change rate of the dielectric constant at [Formula: see text] to [Formula: see text] is 1% to −15.20%, basically meeting the requirements of X9R. These results indicate that the [email protected] (BT–BZN) is a promising candidate for high temperature stable materials.

Entropy-stabilized metal oxide solid solutions as CO oxidation catalysts with high-temperature stability

2018 ◽  
Vol 6 (24) ◽  
pp. 11129-11133 ◽  
Author(s):  
Hao Chen ◽  
Jie Fu ◽  
Pengfei Zhang ◽  
Honggen Peng ◽  
Carter W. Abney ◽  
...  
Keyword(s):  
High Temperature ◽  
Metal Oxide ◽  
Co Oxidation ◽  
Solid Solutions ◽  
Supported Catalysts ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Entropy Maximization ◽  
New Class ◽  
New Strategy

This work reports a new strategy toward the design of a new class of supported catalysts with intrinsic high-temperature stabilities through entropy maximization.

THE RECIPROCAL SALT-PAIR SYSTEM: SODIUM CHLORIDE – AMMONIUM SULPHITE – SODIUM SULPHITE – AMMONIUM CHLORIDE – WATER AT 20 °C. AND 60 °C.: PART II: THE QUATERNARY SYSTEM

1955 ◽  
Vol 33 (5) ◽  
pp. 787-796 ◽  
Author(s):  
J. A. Labash ◽  
G. R. Lusby
Keyword(s):  
Sodium Chloride ◽  
Ammonium Chloride ◽  
Solid Solutions ◽  
Quaternary System ◽  
Sodium Sulphate ◽  
Sodium Sulphite ◽  
Chloride Water ◽  
Solid Phases ◽  
System Sodium

In the above quaternary system at 60 °C., besides those representing the four salts at the corners of the Janecke diagram two other saturation areas were found. At 20 °C. there are three, and possibly more than three additional areas. In the course of the present work it was not possible to establish the nature of the solid phases in these additional areas of the quaternary system. However, the data of Lewis and Rivett suggest that at least some of these unknown areas may indicate the presence of different solid solutions of sodium sulphate in sodium sulphite. This quaternary system appears to be a rather complex one and much further work remains to be done in order to complete the knowledge of it at 60 °C. and 20 °C., particularly at the latter temperature.

THE FORMATION AND COEXISTENCE OF GIBBSITE, BOEHMITE, ALUMINA AND ALUNITE AT ROOM TEMPERATURE

1982 ◽  
Vol 62 (2) ◽  
pp. 327-332 ◽  
Author(s):  
S. SHAH SINGH
Keyword(s):  
Room Temperature ◽  
Thermal Conditions ◽  
Laboratory Conditions ◽  
Aluminum Sulphate ◽  
Aluminum Compounds ◽  
Solid Phases

The formation and coexistence of four aluminum compounds, namely, gibbsite (Al(OH)3), boehmite (AlOOH), alumina (Al2O3) and alunite (NaAl3(OH)6(SO4)2) is reported under laboratory conditions. These solid phases were formed as hydrolytic products of aluminum sulphate solutions at room temperature. These results provide evidence that thermal conditions are not essential and not the only conditions under which boehmite and alumina are formed.

Characterization of Lanthanoid Phases Formed Upon Glass Dissolution in Salt Solutions

1991 ◽  
Vol 257 ◽  
Author(s):  
Anette Rother ◽  
Werner Lutze ◽  
Peter Schubert-Bischoff
Keyword(s):  
Nuclear Waste ◽  
Solid Solutions ◽  
Type Material ◽  
Salt Solutions ◽  
Detailed Characterization ◽  
Glass Dissolution ◽  
Nuclear Waste Glass ◽  
Solid Phases ◽  
Additional Barrier

ABSTRACTThis communication gives a detailed characterization of some molybdate solid solutions and cerianite-type material which formed on the French borosilicate nuclear waste glass R7T7 upon corrosion in various saturated salt solutions at 110°C, 150 °C and 190 °C. The glass contained lanthanoid elements, such as neodymium, lanthanum, praseodymium, cerium and yttrium, but did not contain actinoid elements, except uranium and thorium. Various solid solutions containing lanthanoids (Ln) were found on the glass surface after corrosion, including powellite solid solutions and cerianite-type material. The secondary solid phases are characterized based on quantitative microchemical and structural analyses. These phases are expected to incorporate actinoids such as americium and curium in acid magnesiumcontaining salt solutions. The phases then constitute an additional barrier against migration of these radionuclides, which would otherwise be in the aqueous phase.

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