Some considerations regarding the determination of the activation energy of solid-state reactions from a series of isothermal data

1984 ◽  
Vol 29 (2) ◽  
pp. 243-250 ◽  
Author(s):  
J. M. Criado ◽  
M. Gonzalez ◽  
A. Ortega ◽  
C. Real
1998 ◽  
Vol 323 (1-2) ◽  
pp. 101-107 ◽  
Author(s):  
K.V Tomashevitch ◽  
S.V Kalinin ◽  
A.A Vertegel ◽  
N.N Oleinikov ◽  
V.A Ketsko ◽  
...  

1999 ◽  
Vol 54 (2) ◽  
pp. 252-260 ◽  
Author(s):  
P. Schmidt ◽  
C. Hennig ◽  
H. Oppermann

The phase relations in the ternary system Bi/Te/O have been determined in previous studies by solid state reactions. Thermodynamical data have now been obtained for the pertinent equilibria. The heats of solution of Bi2O3, Bi12TeO20, Bi10Te2O19, Bi16Te5O34, Bi2TeO5, Bi2Te2O7, Bi2Te4O11 and TeCl4 were determined in 4N HCl. From these the enthalpies of formation of bismuth tellurites at 298 K have been derived:⊿H°b (Bi12TeO20, f, 298) = -901,6 ± 8 kcal/mol,⊿H°b (Bi10Te2O19, f, 298) = -856,1 ± 9 kcal/mol,⊿H°b (Bi16Te5O34, f, 298) = -1519,5 ± 17 kcal/mol,⊿H°b (Bi2TeO5, f, 298)= -222,8 ± 3 kcal/mol,⊿H°b (Bi2Te2O7, f, 298)= -299,4 ± 4 kcal/mol,⊿H°b (Bi2Te4O11, f, 298)= -448,2 ± 7 kcal/mol.


2012 ◽  
Vol 51 (4) ◽  
pp. 376-382
Author(s):  
J. Karasa ◽  
J. Kostjukovs ◽  
A. Palaša ◽  
A. Actiņš

A procedure of smectite containing clay enrichment has been optimized, and the process of sedimentation has been studied. The new enrichment based method for quantitative determination of clay fraction in smectite containing sediment was developed. A new method for obtaining organoclays from enriched smectite clays has been investigated. The method is based on solid-state reaction between smectite and organic compounds, where organic molecules can be intercalated in dried clay mineral (montmorillonite) by solid-state reactions, without or with use of solvents. The enriched clay and the obtained organoclay samples were characterized with X-ray powder diffraction (PXRD).


1976 ◽  
Vol 59 (7-8) ◽  
pp. 327-329 ◽  
Author(s):  
N. A. EISSA ◽  
A. A. BAHGAT ◽  
A. H. MOHAMED ◽  
S. A. SALEH

1977 ◽  
Vol 8 (1) ◽  
pp. no-no
Author(s):  
N. A. EISSA ◽  
A. A. BAHGAT ◽  
A. H. MOHAMED ◽  
S. A. SALEH

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 139
Author(s):  
Yannis Vasilopoulos ◽  
Eliška Skořepová ◽  
Miroslav Šoóš

It is well known that the implementation of the conventional model-fitting (CMF) method leads to several indistinguishable ‘best’ candidate models (BCMs) for a single-step isothermal solid-state reaction (ISSR), meaning that subjective selection becomes unavoidable. Here, we developed a more robust comprehensive model-fitting method (COMF) which, while maintaining the mathematical simplicity of CMF, utilizes a ranking criterion that enables automatic and unambiguous determination of the BCM. For each model evaluated, COMF, like CMF, fits the integral reaction rate, but, unlike CMF, it also fits the experimental conversion fraction and reaction speed. From this, three different determination coefficients are calculated and combined to rank the considered models. To validate COMF, we used two sets of experimental kinetic data from the literature regarding the isothermal desolvation of pharmaceutical solvates: (i) tetrahydrofuran solvates of sulfameter, and (ii) methanol solvates of ciclesonide. Our results suggest that from an algorithmic perspective, COMF could become the model-fitting method of choice for ISSRs making the selection of BCM easier and more reliable.


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