Determination of the Enthalpy of Formation of SmOCl by Solution Calorimetry

ChemInform ◽  
2003 ◽  
Vol 34 (18) ◽  
Author(s):  
Heinrich Oppermann ◽  
Peer Schmidt ◽  
Dao Quoc Huong ◽  
Claudia Hennig
Keyword(s):  
Enthalpy Of Formation ◽  
Solution Calorimetry ◽  
The Enthalpy Of Formation

Experimental determination of the enthalpy of formation of dibenzo- p-dioxin

2002 ◽  
Vol 34 (3) ◽  
pp. 385-390 ◽  
Author(s):  
S.M. Pimenova ◽  
S.V. Melkhanova ◽  
V.P. Kolesov ◽  
P.I. Demyanov ◽  
A.N. Fedotov ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Enthalpy Of Formation ◽  
The Enthalpy Of Formation

Silicon nitride: Enthalpy of formation of the α- and β-polymorphs and the effect of C and O impurities

1999 ◽  
Vol 14 (5) ◽  
pp. 1959-1968 ◽  
Author(s):  
Jian-jie Liang ◽  
Letitia Topor ◽  
Alexandra Navrotsky ◽  
Mamoru Mitomo
Keyword(s):  
Solid Solution ◽  
Enthalpy Of Formation ◽  
Solution Calorimetry ◽  
Molar Enthalpy ◽  
Solid Solution Series ◽  
Solution Series ◽  
Α Phase ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
The Enthalpy Of Formation

High-temperature oxidative drop solution calorimetry was used to measure the enthalpy of formation of α− and β−Si3N4. Two different solvents, molten alkali borate (48 wt% LiBO2 · 52 wt% NaBO2) at 1043 and 1073 K and potassium vanadate (K2O · 3V2O5) at 973 K, were used, giving the same results. Pure α− and β−Si3N4 polymorphs have the same molar enthalpy of formation at 298 K of −850.9 ± 22.4 and −852.0 ± 8.7 kJ/mol, respectively. The unit cell dimensions of impure α−Si3N4 samples depend linearly on the O and C impurity contents, and so does the molar enthalpy of formation. The energetic stability of the α−Si3N4phase decreases when the sample contains O and C impurities. The experimental evidence strongly suggests that the impurities dissolve into the α−Si3N4 structure to form a (limited) isostructural solid solution series but that this solid solution series is energetically less stable than a mechanical mixture of pure (α or β) Si3N4, SiO2, and SiC. Thus, the α-phase is not stabilized by impurities and is probably always metastable.

Thermochemistry of lanthanum zirconate pyrochlore

2009 ◽  
Vol 24 (11) ◽  
pp. 3350-3357 ◽  
Author(s):  
A.V. Radha ◽  
Sergey V. Ushakov ◽  
Alexandra Navrotsky
Keyword(s):  
Melting Point ◽  
Enthalpy Of Formation ◽  
Sodium Molybdate ◽  
Solution Calorimetry ◽  
Standard Enthalpy Of Formation ◽  
Lanthanum Zirconate ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide ◽  
The Enthalpy Of Formation

A thermodynamic study was carried out to resolve discrepancies in the enthalpy of formation and related parameters for lanthanum zirconate pyrochlore. The homogeneity field for single phase pyrochlore formation was determined to be ∼33–35 mol% La2O3 at 1500 °C. High-temperature oxide melt drop solution calorimetry was performed in sodium molybdate and lead borate solvents on three compositions ranging from La1.98Zr2.01O7 to La2.07Zr1.95O7. The enthalpy of formation from oxides at 25 °C, ΔH0f,ox, for stoichiometric lanthanum zirconate pyrochlore is −107.3 ± 5.1 kJ/mol, and the standard enthalpy of formation from elements, ΔH0f,el, is −4102.2 ± 6.0 kJ/mol. La2Zr2O7 pyrochlore was found by differential thermal analysis to be stable up to its melting point. The melting point and the fusion enthalpy of La2Zr2O7 pyrochlore were measured as 2295 ± 10 °C and ∼350 kJ/mol, respectively.

First-principles determination of the enthalpy of formation of Mn–Si phases

2014 ◽  
Vol 188 ◽  
pp. 49-52 ◽  
Author(s):  
Alexandre Berche ◽  
Jean-Claude Tédenac ◽  
Philippe Jund
Keyword(s):  
Enthalpy Of Formation ◽  
First Principles ◽  
The Enthalpy Of Formation
Sign in / Sign up

Export Citation Format

Share Document