Enthalpies of formation of CaAl4O7 and CaAl12O19 (hibonite) by high temperature, alkali borate solution calorimetry

1988 ◽  
Vol 52 (6) ◽  
pp. 1729-1736 ◽  
Author(s):  
C.A Geiger ◽  
O.J Kleppa ◽  
B.O Mysen ◽  
J.M Lattimer ◽  
L Grossman
Keyword(s):  
High Temperature ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
Borate Solution

Thermochemistry of Si6–zAlzOzN8–z(z = 0 to 3.6) materials

1999 ◽  
Vol 14 (12) ◽  
pp. 4630-4636 ◽  
Author(s):  
Jian-Jie Liang ◽  
Alexandra Navrotsky ◽  
Valerie J. Leppert ◽  
Michael J. Paskowitz ◽  
Subhash H. Risbud ◽  
...  
Keyword(s):  
Free Energy ◽  
High Temperature ◽  
Alkali Metal ◽  
Nitrogen Content ◽  
Configurational Entropy ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
Accelerate Oxidation ◽  
Oxygen Gas ◽  
Metal Borate

Enthalpies of formation were determined for β-sialon phases (Si6–zAlzOzN8–z, z = 0.46 to 3.6) by high-temperature oxidative drop solution calorimetry using an alkali-metal borate (52 wt% LiBo2; 48 wt% NaBO2) solvent. Oxygen gas was bubbled through the melt to accelerate oxidation of the oxynitride samples during dissolution. Sialons near z = 2 appear less stable energetically than ones with higher or lower nitrogen content. A large configurational entropy contribution for sialons with z > 2 may further stabilize these materials. This larger free energy driving form may be the reason for success in pulse-activated processing of these materials. The enthalpies of formation further suggest that a greater driving form for oxynitride formation exists in batch synthesis using SiO2 rather than Al2O3.

Praseodymium and high-temperature superconductivity: Thermodynamic, structural, and critical correlations

1996 ◽  
Vol 11 (5) ◽  
pp. 1061-1064 ◽  
Author(s):  
V. E. Lamberti ◽  
M. A. Rodriguez ◽  
J. D. Trybulski ◽  
A. Navrotsky
Keyword(s):  
High Temperature ◽  
Solid Solutions ◽  
Thermodynamic Data ◽  
High Temperature Superconductivity ◽  
Thermodynamic Characteristics ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
Critical Temperatures ◽  
Solution Behavior ◽  
Partial Molar Enthalpies

The enthalpies of formation and the partial molar enthalpies of oxidation of polycrystalline LnBa2Cu3Oy (Ln = Pr, Nd, Eu, Gd, Dy, Ho, Tm) and Y1−xPrxBa2Cu3Oy (x = 0.0, 0.1, 0.2, 0.5, 0.8, 0.9, 1.0) have been determined at 298 K by drop-solution calorimetry. The thermodynamic characteristics of Pr123 follow the trends of the trivalent-ion-based Ln123 compounds. The thermodynamic data for the (Y,Pr)123 solid solutions show nonideal solution behavior, but no x-dependent valence instability. The superconducting critical temperatures and the enthalpies of oxidation of the (Y,Pr)123 solid solutions are linearly related.

Enthalpies of formation of LaBO3perovskites (B = Al, Ga, Sc, and In)

2003 ◽  
Vol 18 (10) ◽  
pp. 2501-2508 ◽  
Author(s):  
Jihong Cheng ◽  
Alexandra Navrotsky
Keyword(s):  
High Temperature ◽  
Enthalpy Of Formation ◽  
Solution Calorimetry ◽  
Tolerance Factor ◽  
Enthalpies Of Formation ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide ◽  
First Time ◽  
The Enthalpy Of Formation

Enthalpies of formation from constituent oxides and elements at 298 K were determined by high-temperature oxide melt solution calorimetry for a group of technologically important perovskites LaBO3(B = La, Ga, Sc, and In). Enthalpies of formation from oxides of LaAlO3and LaGaO3are −69.61 ± 3.23 kJ/mol and −52.39 ± 1.99 kJ/mol, respectively. The data were consistent with literature values obtained using other methods. The enthalpies of formation of LaScO3and LaInO3from oxides were reported for the first time as −38.64 ± 2.30 kJ/mol and −23.99 ± 2.31 kJ/mol, respectively. As seen for other perovskites, as the tolerance factor deviates more from unity (in the order Al, Ga, Sc, In), the enthalpy of formation from oxides becomes less exothermic, indicating a less stable structure with respect to the constituent oxides.

scholarly journals Thermodynamic properties of fluorapophyllite-(k) and hydroxylapophyllite-(k)

2019 ◽  
Vol 64 (7) ◽  
pp. 726-732
Author(s):  
L. P. Ogorodova ◽  
L. V. Melchakova ◽  
M. F. Vigasina ◽  
Yu. D. Grytsenko ◽  
D. A. Ksenofontov ◽  
...  
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Thermodynamic Properties ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
Thermochemical Study ◽  
Gibbs Energies ◽  
Natural Minerals ◽  
Temperature Heat

Thermochemical study of natural minerals of the apophyllite group: fluorapophyllite-(K) KCa4[Si8O20]F . 8H2O (Maharashtra, India) (I) and hydroxylapophyllite-(K) KCa4[Si8O20]OH . 8H2O (Norilsk, Russia) (II) were performed on a high-temperature heat-flux microcalorimeter Tian–Calvet “Setaram” (France) using the melt solution calorimetry method. The first data on the enthalpies of formation from the elements for the minerals studied are obtained: -13 205±13 kJ/mol (I) and -13 054±20 kJ/mol (II). The values of their standard entropies and Gibbs energies of formation are estimated.

Energetics of Nitridophosphates PON and “LiNaPON Glasses”

1998 ◽  
Vol 547 ◽  
Author(s):  
F. Tessier ◽  
A. Le Sauze ◽  
R. Marchand ◽  
A. Navrotsky
Keyword(s):  
High Temperature ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
High Temperature Solution ◽  
Thermodynamic Studies ◽  
Temperature Solution

AbstractStructural analogies have been demonstrated between the β-cristobalite, α-quartz and moganite phases of PON and its isoelectronic analog SiO2. Whereas the energetics of silica are well established, no data exist for the energetics of formation of nitridophosphates. High temperature solution calorimetry was used to determine the energetics of PON samples and a series of “LiNaPON oxynitride” glasses. Enthalpies of formation were measured as -371.71 ± 4.45 kJ/mol and -356.14 ± 3.98 for β-cristobalite and amorphous PON respectively and as -961.88 ± 3.86 kJ/mol for a 9 wt% nitrogen containing LiNaPON glass. These values constitute the first set of energetics data necessary to achieve further thermodynamic studies on nitridophosphates.

Enthalpies of Formation of LaMO3 Perovskites (M = Cr, Fe, Co, and Ni)

2005 ◽  
Vol 20 (1) ◽  
pp. 191-200 ◽  
Author(s):  
Jihong Cheng ◽  
Alexandra Navrotsky ◽  
Xiao-Dong Zhou ◽  
Harlan U. Anderson
Keyword(s):  
High Temperature ◽  
Relative Stability ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide

Enthalpies of formation from constituent oxides and elements at 298 K were determined by high-temperature oxide melt solution calorimetry for a group of technologically important perovskites LaMO3 (M = Cr, Fe, Co, and Ni). The enthalpies of formation of LaCrO3 and LaFeO3 from oxides (La2O3 and Cr2O3 or Fe2O3) are –70.06 ± 2.79 kJ/mol and –64.58 ± 2.32 kJ/mol, respectively. The enthalpies of formation of LaCoO3 and LaNiO3 from oxides (La2O3 and CoO or NiO) and O2 are −107.64 ± 1.77 kJ/mol and –57.31 ± 2.55 kJ/mol, respectively. All these data are evaluated and found to be consistent with literature values obtained using other methods. The relative stability among these four perovskites decreases in the order of Cr, Fe, Co, Ni.

Energetics in the brownmillerite-perovskite pseudobinary Ca2Fe2O5-CaTiO3

1994 ◽  
Vol 9 (12) ◽  
pp. 3121-3124 ◽  
Author(s):  
T.R.S. Prasanna ◽  
A. Navrotsky
Keyword(s):  
High Temperature ◽  
Random Distribution ◽  
Configurational Entropy ◽  
Solution Calorimetry ◽  
Enthalpies Of Formation ◽  
High Temperature Solution ◽  
Pseudobinary System ◽  
Octahedral Sites ◽  
Intermediate Phases ◽  
Temperature Solution

The energetics of intermediate phases in the Ca2Fe2O5-CaTiO3 pseudobinary system was determined by high temperature solution calorimetry. The results suggest that both the intermediate compounds Ca3Fe2TiO8 and Ca4Fe2Ti2O11 are entropically stabilized because their enthalpies of formation are positive with respect to a mixture of Ca2Fe2O5 and CaTiO3. At high temperatures, the configurational entropy of the random distribution of Fe and Ti ions on the octahedral sites appears sufficient to stabilize the intermediate phases. The enthalpies of formation from the oxides at 1073 K of Ca2Fe2O5, Ca3Fe2TiO8, and Ca4Fe2Ti2O11 are −45.0 ± 3.8, −123.7 ± 8.0, and −192.7 ± 11.2 kJ/mol, respectively. Their enthalpies of formation from the elements at 298 K are −2139.8 ± 4.4, −3798.4 ± 8.6, and −5447.3 ± 12.2 kJ/mol, respectively.

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