Phase formation processes in natural magnesium silicates of various structures by their ammonium fluoride treatment

2020 ◽  
pp. 28-35
Author(s):  
Sh. M. Sharafeev ◽  
V. M. Pogrebenkov
Keyword(s):  
Phase Formation ◽  
Structural Transformation ◽  
Ammonium Fluoride ◽  
Formation Processes ◽  
Fluoride Treatment ◽  
Ammonium Hexafluorosilicate ◽  
Ammonium Hydrodifluoride ◽  
Magnesium Silicates ◽  
Partial Destruction

The processes of forsterite, enstatite and talc treatment by ammonium fluoride have been studied. The phaseformation processes occurring during firing of fluorinated minerals were studied. It was established that structural silica of minerals reacts with ammonium hydrodifluoride with the formation of ammonium hexafluorosilicate. The sublimation of ammonium hexafluorosilicate leads to remove structural silica from minerals with partial destruction of their structure. The firing of fluorinated minerals leads to their structural transformation with the formation of magnesium nesosilicates and fluoronesosilicates.

Aspects of the phase-formation processes in highly dispersed BaTiO3-based materials

1991 ◽  
Vol 30 (12) ◽  
pp. 1005-1006
Author(s):  
V. I. Lapshin ◽  
E. L. Fokina ◽  
I. A. Kozlovskaya
Keyword(s):  
Phase Formation ◽  
Formation Processes ◽  
Highly Dispersed

scholarly journals Kinetic Investigations of Phaseformation Processes in the BaO-Al2O3-Fe2O3 System

2010 ◽  
Vol 4 (2) ◽  
pp. 91-93
Author(s):  
Nikolay Iloukha ◽  
◽  
Zoya Barsova ◽  
Irina Cwhanovskaya ◽  
Valentina Timofeeva ◽  
...  
Keyword(s):  
Activation Energy ◽  
Phase Formation ◽  
Rate Constant ◽  
Reaction Temperature ◽  
Reaction Rate ◽  
Degree Of Conversion ◽  
Formation Processes ◽  
Kinetic Investigations

The kinetic investigations of phase formation processes in the mixture which contains BaO, Al2O3, Fe2O3 were carried out. The degree of conversion and the activation energy were calculated, the dependence of the reaction rate and the rate constant on reaction temperature was determined.

scholarly journals Study of Phase Formation Processes in Li2ZrO3 Ceramics Obtained by Mechanochemical Synthesis

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 21
Author(s):  
Maxim V. Zdorovets ◽  
Artem L. Kozlovskiy ◽  
Baurzhan Abyshev ◽  
Talgat A. Yensepbayev ◽  
Rizahan U. Uzbekgaliyev ◽  
...  
Keyword(s):  
Phase Formation ◽  
Structural Changes ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Image Data ◽  
Formation Processes ◽  
Ceramic Structure ◽  
Current Voltage ◽  
Average Grain Size ◽  
Temperature Dependences

The article is dedicated to the study of the phase formation processes in Li2ZrO3 ceramics obtained by the method of solid phase synthesis. Interest in these types of ceramics is due to their great potential for use as blanket materials in thermonuclear reactors, as well as being one of the candidates for tritium breeder materials. Analysis of the morphological features of the synthesized ceramics depending on the annealing temperature showed that the average grain size is 90–110 nm; meanwhile the degree of homogeneity is more than 90% according to electronic image data processing results. The temperature dependences of changes in the structural and conducting characteristics, as well as the phase transformation dynamics, have been established. It has been determined that a change in the phase composition by displacing the impurity LiO and ZrO2 phases results in the compaction of ceramics, as well as a decrease in their porosity. These structural changes are due to the displacement of LiO and ZrO2 impurity phases from the ceramic structure and their transformation into the Li2ZrO3 phase. During research, the following phase transformations that directly depend on the annealing temperature were established: LiO/ZrO2/Li2ZrO3 → LiO/Li2ZrO3 → Li2ZrO3. During analysis of the obtained current-voltage characteristics, depending on the annealing temperature, it was discovered that the formation of the Li2ZrO3 ordered phase in the structure results in a rise in resistance by three orders of magnitude, which indicates the dielectric nature of the ceramics.

Modeling of the Phase Formation Processes on the Steel Surface Contacting with Water Medium under Conditions of Deep Geological Repository

2021 ◽  
Vol 20 ◽  
pp. 60-72
Author(s):  
О. М. Lavrynenko ◽  
◽  
B. G. Shabalin ◽  
◽  
Keyword(s):  
Phase Composition ◽  
Phase Formation ◽  
Steel Surface ◽  
Spinel Ferrite ◽  
Corrosion Products ◽  
Chemical Mechanism ◽  
Formation Processes ◽  
Deep Geological Repository ◽  
Iron Oxyhydroxides ◽  
Geological Repository

The experimental modeling of the corrosive phase formation processes was performed under conditions approaching the initial and transitional stages of evolution of the deep geological repository (the hydrogen index of the medium lied in the range of 9–12 and a temperature was 50–70 °C). The specificity of the system of rotating disk electrode made it possible to determine the phase composition of corrosion products formed under oxidative conditions (the near surface layer, NSL) and, conditionally, reductive — on the steel surface (SL) covered by NSL, that significantly complicated the access of oxygen into the reaction area. It was determined that phase composition of the corrosion products at the pH0 values 9–11 was identical and it is regulated by the compensative action of cathodic half-reaction of oxygen reducing on the steel surface. Green Rust and magnetite or non-stoichiometric spinel ferrite characterized by coagulative type of the structure and spherical particle shape were determined as the main phases of SL. Iron oxyhydroxides — goethite and lepidocrocite were presented as the phases of NSL. Increase in the pH0 to 12 changes the chemical mechanism of the corrosion process and it leads to the formation of weak crystallized iron oxyhydroxide phases. It was proved the main phase formed under corrosion of steel at 50–70 °C was spinel ferrite. Its morphology is presented as the cubic shaped particles that evidences about condensingcrystallizing mechanism of their formation. Generally, the presence of Co2+ and Mn2+ cations does not influence on the phase formation process and the phase composition as well, whereas the iron oxyhydroxides with admixture of Mn2+ and Mn3+ oxygen compounds are dominant in the sediment compositions when they are formed in the presence of Mn7+.

Effect of NaNO3 as Enhancer on YBa2Cu4O8 Superconductor Phase Formation via Solid State Technique with Heating at Ordinary Oxygen Pressure

2016 ◽  
Vol 840 ◽  
pp. 326-330
Author(s):  
Choon Min Cheong ◽  
Nursyafiqah Ismail ◽  
Noor Azlina Mohd Sarip ◽  
Noor Hakimah Hamzah ◽  
Nur Aleeya Ameera Ruzman ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Solid State ◽  
Phase Formation ◽  
Oxygen Pressure ◽  
Formation Processes ◽  
Research Groups ◽  
Solid State Method ◽  
Conventional Solid State Method ◽  
State Technique ◽  
State Method

YBa2Cu4O8 has emerged as better choice in superconducting application thank to it strong thermal stability. High pressure techniques had been employed for the preparation of YBa2Cu4O8 but it might costly and/or inconvenient. Several research groups had showed that the YBa2Cu4O8 can also be prepared by conventional solid state method with heating at 1 atm oxygen pressure; however the phase formation processes are yet brief and clear. This work infiltrated the phase formation processes in preparing the YBa2Cu4O8 under solid state method with heating at 1 atm oxygen pressure. The effectiveness of the use of sodium nitrate as an enhancer was brought to light by the experiment results. Significant YBa2Cu4O8 phases were successfully synthesized.

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