Thermodynamics of solution of gypsum and anhydrite in water over a wide temperature range

1984 ◽  
Vol 62 (3) ◽  
pp. 484-488 ◽  
Author(s):  
Horacio R. Corti ◽  
Roberto Fernandez-Prini
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Thermodynamic Properties ◽  
Transition Process ◽  
Calcium Sulphate ◽  
Phase Transition Process ◽  
Different Temperatures ◽  
Pure Phases ◽  
Constant Charge

The solubility of calcium sulphate in water at different temperatures is important for the description of chemical processes occurring in heat exchangers as well as in geothermal processes. Great discrepancies have been reported between experimental and predicted solubilities at high temperature and the transition temperature for the phase transition process (gypsum → anhydrite) is ill-defined.We have analyzed the available data for the solubility of calcium sulphate in water with no added electrolyte. Ion-pairing has been taken into account to calculate the standard thermodynamic properties of the solution process.It is found that the solubility data for gypsum and anhydrite are thermodynamically very consistent. It is possible to obtain the thermodynamic properties of the phase transition from solution data and, at 298.15 K and 101.325 kPa, they are in very good agreement with reported values from measurements with the pure phases. The transition temperature is calculated to be 315.7 ± 0.4 K.It is also shown that the experimental data agree with values predicted for high temperature by employing well-established methods of calculation of solution thermodynamic properties (e.g., principles of correspondence and of constant charge).

The structural phase transition process of free-standing monoclinic vanadium dioxide micron-sized rods: temperature-dependent Raman study

RSC Advances ◽  
2015 ◽  
Vol 5 (101) ◽  
pp. 83139-83143 ◽  
Author(s):  
Huafang Zhang ◽  
Quanjun Li ◽  
Pengfei Shen ◽  
Qing Dong ◽  
Bo Liu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Vanadium Dioxide ◽  
Structural Phase ◽  
Transition Process ◽  
Temperature Dependent ◽  
Free Standing ◽  
Lower Phase ◽  
Phase Transition Process ◽  
Raman Study

Micro-sized rods show a lower phase transition temperature than nano-sized rods, and this is interpreted on the basis of nucleating defects.

scholarly journals To the Methodology of Phase Transition Temperature Determination in Aqueous Solutions of Thermo-Sensitive Polymers

2020 ◽  
Vol 22 (2) ◽  
pp. 129
Author(s):  
G.A. Mun ◽  
I. Moldakhan ◽  
S.B. Kabdushev ◽  
B.B. Yermukhambetova ◽  
R. Shaikhutdinov ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Aqueous Solutions ◽  
Temperature Interval ◽  
Phase State ◽  
Transition Process ◽  
Phase Portraits ◽  
Quantitative Parameter ◽  
Phase Transition Process

An advanced methodology of phase transition determination in aqueous solutions of thermo-sensitive polymers by using of the phase portraits method has been suggested. The methodology allows highly accurate determining the temperature when exactly a half of molecules loses solubility (from the maximum number that can go to another phase state under given conditions). It is shown that since phase transition passes usually in a wide enough temperature interval this indicator should be used as a quantitative parameter that characterizes phase transition process. Additionally the suggested methodology allows introducing one more quantitative parameter that reflects a sharpness of phase transition. The methodology is verified by an example of phase transitions study in aqueous solutions of thermo-sensitive copolymers based on N-vinylpyrrolidone and vinyl propyl ether.

scholarly journals Influence of Alkali Metal Substitution on the Phase Transition Behavior of CsGaQ2 (Q = S, Se)

2017 ◽  
Author(s):  
Daniel Friedrich ◽  
Marc Schlosser ◽  
Martin Etter ◽  
Arno Pfitzner
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
High Temperature ◽  
Solid Solutions ◽  
Transition Process ◽  
Miscibility Gap ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Transition Process ◽  
Complete Miscibility

The formation of solid solution series Cs1-xMxGaQ2-mC64 (M = K, Rb; Q = S, Se; x = 0–1) was studied by X-ray diffraction and spectroscopic methods, revealing a complete miscibility of CsGaQ2-mC64 with RbGaQ2 and KGaSe2, and a large miscibility gap with KGaS2. All solid solution members exhibit similar Raman spectra, indicating the covalent Ga-Q bonding character. The similar optical band gaps likewise further contribute to this conclusion. Up to a degree of substitution, these solid solutions undergo a phase transition similar to CsGaQ2-mC64. The influence of the substitution parameter x on phase transition process was investigated in situ using high-temperature X-ray powder diffraction experiments. Phase-pure solid solutions of the high-temperature polymorphs Cs1-xMxGaQ2-mC16 were obtained up to xmax(K) = 0.1 and xmax(Rb) = 0.3. The crystal structures of these new CsGaQ2-mC16 analogous high-temperature phases were refined from synchrotron diffraction data by Rietveld-refinement.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

scholarly journals Role of temperature in the numerical analysis of CaO under high pressure

2010 ◽  
Vol 8 (1) ◽  
pp. 126-133 ◽  
Author(s):  
Purvee Bhardwaj ◽  
Sadhna Singh
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Numerical Analysis ◽  
Thermodynamic Properties ◽  
Elastic Constants ◽  
Volume Change ◽  
Thermodynamical Properties ◽  
Phase Transition Pressure ◽  
Different Temperatures

AbstractIn this paper we focus on the elastic and thermodynamic properties of the B1 phase of CaO by using the modified TBP model, including the role of temperature. We have successfully obtained the phase transition pressure and volume change at different temperatures. In addition elastic constants and bulk modulus of B1 phase of CaO at different temperatures are discussed. Our results are comparable with the previous ones at high temperatures and pressures. The thermodynamical properties of the B1 phase of CaO are also predicted.

The effect of Argon pressure dependent V thin film on the phase transition process of (020) VO2 thin film

2018 ◽  
Vol 427 ◽  
pp. 304-311 ◽  
Author(s):  
Yifan Meng ◽  
Kang Huang ◽  
Zhou Tang ◽  
Xiaofeng Xu ◽  
Zhiyong Tan ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Transition ◽  
Transition Process ◽  
Argon Pressure ◽  
Phase Transition Process

Exploration of Doubly Thermal Phase Transition Process of PDEGA-b-PDMA-b-PVCL in Water

Langmuir ◽  
2016 ◽  
Vol 32 (26) ◽  
pp. 6691-6700 ◽  
Author(s):  
Zhangxin Ye ◽  
Youcheng Li ◽  
Zesheng An ◽  
Peiyi Wu
Keyword(s):  
Phase Transition ◽  
Transition Process ◽  
Thermal Phase Transition ◽  
Phase Transition Process ◽  
Thermal Phase
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