scholarly journals Thermodynamics of phase transitions in the subsolidus domain of the FeO–MgO–TiO2 system

2021 ◽  
pp. 12-15
Author(s):  
O.M. Borysenko ◽  
S.M. Logvinkov ◽  
G.M. Shabanova ◽  
I.A. Ostapenko
Keyword(s):  
Phase Transitions ◽  
Gibbs Energy ◽  
Phase Equilibria ◽  
Thermodynamic Data ◽  
Exchange Reactions ◽  
Two Phase ◽  
Free Gibbs Energy ◽  
Temperature Range ◽  
System Changes ◽  
Temperature Ranges

This paper gives consideration to the three-component FeO–MgO–TiO2 system that is a part of the four-component MgO–Al2O3–FeO–TiO2 system which serves to produce materials with valuable properties. The structure of binary FeO–TiO2 and MgO–TiO2 systems is described and the available data on the FeO–MgO–TiO2 system are analyzed. We present the thermodynamic data on all system compounds and calculate change of the free Gibbs energy in the temperature range of 800 to 1900 K for three exchange reactions. It was established that the triangulation of the FeO–MgO–TiO2 system changes in three following temperature ranges: at the temperatures of up to 1115 К, at 1115 to 1413 К (the restructuring of conodes here occurs) and above 1413 K (stable pseudobrookite is formed). It was shown that the following two-phase equilibria are stable: MgTi2O5–FeTiO3, FeTiO3–MgTiO3, MgTiO3–Fe2TiO4, Fe2TiO4–Mg2TiO4 and Mg2TiO4–FeO at the temperatures of up to 1115 K; MgTi2O5–FeTiO3, FeTiO3–MgTiO3, FeTiO3–Mg2TiO4, Fe2TiO4–Mg2TiO4 and Mg2TiO4–FeO in the temperature range of 1115 to 1413 K; and MgTi2O5–FeTi2O5, MgTi2O5–FeTiO3, FeTiO3–MgTiO3, FeTiO3–Mg2TiO4, Fe2TiO4–Mg2TiO4 and Mg2TiO4–FeO at the temperatures of above 1413 K.

scholarly journals Фазовые превращения в однокомпонентных многофазных системах: фазово-полевой подход

2022 ◽  
Vol 92 (2) ◽  
pp. 187
Author(s):  
В.Г. Лебедев
Keyword(s):  
Phase Transitions ◽  
Gibbs Energy ◽  
Phase Field ◽  
Complete System ◽  
Nonequilibrium System ◽  
Phase Model ◽  
Multiphase Model ◽  
Two Phase ◽  
Dissipative Dynamics ◽  
Phase Fields

The problems of constructing a multiphase model of the phase field for the processes of phase transitions of the first kind are considered. Based on the Gibbs energy of the complete system expressed in terms of antisymmetrized combinations of phase fields, it is shown that the equations of dissipative dynamics of a locally nonequilibrium system follow from the condition of its monotonic decrease, preserving the normalization of the sum of variables by one and the following properties of the previously known two-phase model.

RAMAN AND INFRARED STUDY OF PHASE TRANSFORMATION IN CRYSTALLINE HYDROGEN IODIDE AND DEUTERIUM IODIDE HI AND DI

1989 ◽  
Vol 03 (11) ◽  
pp. 1671-1679 ◽  
Author(s):  
W.S. TSE ◽  
C.S. FANG ◽  
A. ANDERSON ◽  
B.H. TORRIE
Keyword(s):  
Phase Transformation ◽  
Phase Transitions ◽  
Melting Point ◽  
Infrared Spectra ◽  
Hydrogen Iodide ◽  
Temperature Dependent ◽  
Two Phase ◽  
Infrared Study ◽  
X Ray ◽  
Temperature Range

Raman and infrared spectra of polycrystalline HI and DI in the region of lattice and internal modes for all three phases have been recorded over the temperature range 18 K to the melting point. The temperature dependent Raman and infrared results are consistent with the X-ray and neutron work that two phase transitions occur at HI and DI involving reorientation of the HI and DI molecules as a whole.

Investigation of the Phase Transition at 67.17 K in the Thiourea-CCl4 Inclusion Compound. As Studied by 14N NQR

1994 ◽  
Vol 49 (1-2) ◽  
pp. 433-438 ◽  
Author(s):  
J. El Ghallali ◽  
M. Gourdji ◽  
L. Guibé ◽  
A. Péneau
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Carbon Tetrachloride ◽  
Inclusion Compound ◽  
Central Line ◽  
Host Lattice ◽  
Central Component ◽  
Two Phase ◽  
Temperature Range ◽  
Calorimetric Measurements

Abstract The 14N NQR from the host lattice of the thiourea-carbon tetrachloride inclusion compound. From calorimetric measurements, two phase transitions are known to occur at 67.2 K and 41.3 K in this compound. Above the 67.2 K transition, the 14N NQR spectrum consists of one resonance, though a small splitting of about 0.5 kHz is seen at temperatures up to ca. 105 K. Below the transition, the resonance appears as a central component, in continuation of the resonance above the transition, and two satellites at + 10 kHz and -8 kHz from the central line. The transition from the single resonance to a fully resolved spectrum takes place in a temperature range of less than one kelvin. The results are compared with those previously obtained with the thiourea-cyclohexane inclusion compound.

Two-Phase Flow with Phase Transitions Instability

1997 ◽  
Vol 28 (4-6) ◽  
pp. 273-276
Author(s):  
B. V. Kichatov ◽  
I. V. Boyko
Keyword(s):  
Phase Transitions ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase

On the nature of the phase transitions of aluminosilicate perrhenate sodalite

2020 ◽  
Vol 235 (6-7) ◽  
pp. 213-223
Author(s):  
Hilke Petersen ◽  
Lars Robben ◽  
Thorsten M. Gesing
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transitions ◽  
Decomposition Temperature ◽  
Second Phase ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Two Phase ◽  
Structure Property Relationships ◽  
Heat Capacity Measurements

AbstractThe temperature-dependent structure-property relationships of the aluminosilicate perrhenate sodalite |Na8(ReO4)2|[AlSiO4]6 (ReO4-SOD) were analysed via powder X-ray diffraction (PXRD), Raman spectroscopy and heat capacity measurements. ReO4-SOD shows two phase transitions in the investigated temperature range (13 K < T < 1480 K). The first one at 218.6(1) K is correlated to the transition of dynamically ordered $P\overline{4}3n$ (> 218.6(1 K) to a statically disordered (<218.6(1) K) SOD template in $P\overline{4}3n$. The loss of the dynamics of the template anion during cooling causes an increase of disorder, indicated by an unusual intensity decrease of the 011-reflection and an increase of the Re-O2 bond length with decreasing temperature. Additionally, Raman spectroscopy shows a distortion of the ReO4 anion. Upon heating the thermal expansion of the sodalite cage originated in the tilt-mechanism causes the second phase transition at 442(1) K resulting in a symmetry-increase from $P\overline{4}3n$ to $Pm\overline{3}n$, the structure with the sodalites full framework expansion. Noteworthy is the high decomposition temperature of 1320(10) K.

scholarly journals Thermodynamics and Machine Learning Based Approaches for Vapor–Liquid–Liquid Phase Equilibria in n-Octane/Water, as a Naphtha–Water Surrogate in Water Blends

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 413
Author(s):  
Sandra Lopez-Zamora ◽  
Jeonghoon Kong ◽  
Salvador Escobedo ◽  
Hugo de Lasa
Keyword(s):  
Machine Learning ◽  
Liquid Phase ◽  
Phase Equilibria ◽  
Aspen Plus ◽  
Phase Region ◽  
Two Phase ◽  
Technical Literature ◽  
Phase Liquid ◽  
Liquid Vapor ◽  
Vapor Liquid

The prediction of phase equilibria for hydrocarbon/water blends in separators, is a subject of considerable importance for chemical processes. Despite its relevance, there are still pending questions. Among them, is the prediction of the correct number of phases. While a stability analysis using the Gibbs Free Energy of mixing and the NRTL model, provide a good understanding with calculation issues, when using HYSYS V9 and Aspen Plus V9 software, this shows that significant phase equilibrium uncertainties still exist. To clarify these matters, n-octane and water blends, are good surrogates of naphtha/water mixtures. Runs were developed in a CREC vapor–liquid (VL_ Cell operated with octane–water mixtures under dynamic conditions and used to establish the two-phase (liquid–vapor) and three phase (liquid–liquid–vapor) domains. Results obtained demonstrate that the two phase region (full solubility in the liquid phase) of n-octane in water at 100 °C is in the 10-4 mol fraction range, and it is larger than the 10-5 mol fraction predicted by Aspen Plus and the 10-7 mol fraction reported in the technical literature. Furthermore, and to provide an effective and accurate method for predicting the number of phases, a machine learning (ML) technique was implemented and successfully demonstrated, in the present study.

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