Thermochemistry of Hf-Zirconolite, CaHf Ti2O7

1999 ◽  
Vol 556 ◽  
Author(s):  
Robert L. Putnam ◽  
Alexandra Navrotsky ◽  
Brian F. Woodfield ◽  
Jennifer L. Shapiro ◽  
Rebecca Stevens ◽  
...  
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Low Temperature ◽  
Adiabatic Calorimetry ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide ◽  
Capacity Data

AbstractThe formation enthalpy, - 3752.3 ± 4.7 kJ·mol−1, of Hf-zirconolite, CaHfTi2O7, was obtained using high temperature oxide-melt solution calorimetry. Combined with heat capacity data obtained using low temperature adiabatic calorimetry we report the heat capacity (Cp) and the standard molar formation energetics (ΔH°f. elements, Δ S°T, and ΔG°f. elements)for Hf-zirconolite from T = 298.15 K to T = 1500 K. Comparison of Hf-zirconolite with Zr-zirconolite is made.

Formation Enthalpies of Tetravalent Lanthanide Perovskites by High Temperature Oxide Melt Solution Calorimetry

2002 ◽  
Vol 718 ◽  
Author(s):  
S. V. Ushakov ◽  
J. Cheng ◽  
A. Navrotsky ◽  
J. R. Wu ◽  
S. M. Haile
Keyword(s):  
High Temperature ◽  
Rietveld Method ◽  
Thermal Analyses ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Cell Parameters ◽  
Oxide Melt ◽  
Formation Enthalpies ◽  
High Temperature Oxide ◽  
Temperature Oxide

AbstractHigh-temperature oxide melt solution calorimetry was used to measure formation enthalpies for several compositions of perovskites of nominal stoichiometry BaPrO3 and BaCeO3. Samples were synthesized from chemical solution methods followed by calcination at 1100-1300°C. PrO2 was synthesized by oxidation of Pr6O11 in an oxygen flow at 280°C. The samples were characterized by microprobe, thermogravimetric and differential thermal analyses. Cell parameters were refined by the Rietveld method. Barium excess in the samples with respect to ideal stoichiometry was detected. Drop solution enthalpies were measured in a Calvet type twin microcalorimeter, using 3Na2O·4MoO3 solvent at 702°C. Preliminary values of the formation enthalpy of BaPrO3 and BaCeO3 from oxides were -70 ±10 kJ/mol and -51 ±10 kJ/mol, respectively. They fall on the normal trend of energetics versus Goldschmidt tolerance factor and do not show any special stabilization of BaPrO3 relative to other MLnO3 perovskites.

scholarly journals Thermodynamics of Molybdenum Trioxide (MoO3) Encapsulated in Zeolite Y

2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Andrew Strzelecki ◽  
Cody Cockreham ◽  
Vitaliy Goncharov ◽  
Houqian Li ◽  
...  
Keyword(s):  
Molybdenum Trioxide ◽  
Zeolite Y ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Metal Species ◽  
Enthalpies Of Formation ◽  
Host Interactions ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide

Zeolites with encapsulated transition metal species are extensively applied in the chemical industry as heterogenous catalysts for favorable kinetic pathways. To elucidate the energetic insights into formation of subnano-sized molybdenum trioxide (MoO) encapsulated/confined in zeolite Y (FAU) from constituent oxides, we performed a systematic experimental thermodynamic study using high temperature oxide melt solution calorimetry as the major tool. Specifically, the formation enthalpy of each MoO/FAU is less endothermic than corresponding zeolite Y, suggesting enhanced thermodynamic stability. As Si/Al ratio increases, the enthalpies of formation of MoO/FAU with identical loading (5 Mo-wt%) tend to be less endothermic, ranging from 61.1 ± 1.8 (Si/Al = 2.9) to 32.8 ± 1.4 kJ/mol TO (Si/Al = 45.6). Coupled with spectroscopic, structural and morphological characterizations, we revealed intricate energetics of MoO – zeolite Y guest – host interactions likely determined by the subtle redox and/or phase evolutions of encapsulated MoO.

scholarly journals Development of high-temperature oxide melt solution calorimetry for p-block element containing materials – CORRIGENDUM

2020 ◽  
pp. 1-1
Author(s):  
Mykola Abramchuk ◽  
Kristina Lilova ◽  
Tamilarasan Subramani ◽  
Ray Yoo ◽  
Alexandra Navrostky
Keyword(s):  
High Temperature ◽  
Solution Calorimetry ◽  
Block Element ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide

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 Development of high-temperature oxide melt solution calorimetry for p-block element containing materials – CORRIGENDUM

2021 ◽  
Vol 36 (3) ◽  
pp. 785-785
Author(s):  
Mykola Abramchuk ◽  
Kristina Lilova ◽  
Tamilarasan Subramani ◽  
Ray Yoo ◽  
Alexandra Navrostky
Keyword(s):  
High Temperature ◽  
Solution Calorimetry ◽  
Block Element ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide

Thermochemistry of the liquid bismuth(III) oxide – boron oxide: a new solvent for oxide melt solution calorimetry

1995 ◽  
Vol 73 (3) ◽  
pp. 425-430 ◽  
Author(s):  
Jacques Rogez ◽  
Jean Claude Mathieu
Keyword(s):  
High Temperature ◽  
Boron Oxide ◽  
Solution Calorimetry ◽  
Physicochemical Study ◽  
Oxide Melt ◽  
Liquid Bismuth ◽  
High Temperature Oxide ◽  
Temperature Oxide

In solution calorimetry, the choice of solvent is important. Some criteria for this choice for oxide melt solution calorimetry are reviewed. A new solvent is proposed and the corresponding physicochemical study is presented. Some structural interpretations are suggested for these Bi2O3–B2O3 melts. Keywords: thermochemistry, calorimetry, high temperature, oxide melt.

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.

Thermochemistry of the alkali rare-earth double phosphates, A3RE(PO4)2

2004 ◽  
Vol 19 (7) ◽  
pp. 2165-2175 ◽  
Author(s):  
Sergey V. Ushakov ◽  
Alexandra Navrotsky ◽  
J. Matt Farmer ◽  
Lynn A. Boatner
Keyword(s):  
Phase Transition ◽  
Rare Earth ◽  
High Temperature ◽  
Structural Phase ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Scanning Calorimetry ◽  
Oxide Melt ◽  
Reversible Phase Transition ◽  
High Temperature Oxide

The formation enthalpies for alkali rare-earth compounds of the type K3RE(PO4)2 where RE = Sc, Y, Lu, Er, Ho, Dy, Gd, Nd, or Ce and for A3Lu(PO4)2 compounds with A = K, Rb, or Cs were determined using high-temperature oxide-melt solution calorimetry. Structural phase transitions were observed and characterized using differential scanning calorimetry and high-temperature x-ray diffraction. The formation enthalpy of the K3RE(PO4)2 phases from oxides becomes more exothermic with increasing rare-earth radius for the K3RE(PO4)2 series and with increasing alkali radius for the A3Lu(PO4)2 compounds. The K3RE(PO4)2 phases are stable with respect to anhydrous K3PO4 and REPO4. The monoclinic K3RE(PO4)2 compounds undergo a reversible phase transition to a hexagonal (glaserite-type) structure with a phase transition temperature that increases from −99 to 1197 °C with increasing RE ionic radius going from Lu to Ce.

scholarly journals Thermodynamics of Molybdenum Trioxide Encapsulated in Zeolite Y

2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Andrew Strzelecki ◽  
Cody Cockreham ◽  
Vitaliy Goncharov ◽  
Houqian Li ◽  
...  
Keyword(s):  
Molybdenum Trioxide ◽  
Zeolite Y ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Metal Species ◽  
Enthalpies Of Formation ◽  
Host Interactions ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide

Zeolites with encapsulated transition metal species are extensively applied in the chemical industry as heterogenous catalysts for favorable kinetic pathways. To elucidate the energetic insights into formation of subnano-sized molybdenum trioxide (MoO) encapsulated/confined in zeolite Y (FAU) from constituent oxides, we performed a systematic experimental thermodynamic study using high temperature oxide melt solution calorimetry as the major tool. Specifically, the formation enthalpy of each MoO/FAU is less endothermic than corresponding zeolite Y, suggesting enhanced thermodynamic stability. As Si/Al ratio increases, the enthalpies of formation of MoO/FAU with identical loading (5 Mo-wt%) tend to be less endothermic, ranging from 61.1 ± 1.8 (Si/Al = 2.9) to 32.8 ± 1.4 kJ/mol TO (Si/Al = 45.6). Coupled with spectroscopic, structural and morphological characterizations, we revealed intricate energetics of MoO – zeolite Y guest – host interactions likely determined by the subtle redox and/or phase evolutions of encapsulated MoO.

scholarly journals Development of high-temperature oxide melt solution calorimetry for p-block element containing materials

2020 ◽  
Vol 35 (16) ◽  
pp. 2239-2246 ◽  
Author(s):  
Mykola Abramchuk ◽  
Kristina Lilova ◽  
Tamilarasan Subramani ◽  
Ray Yoo ◽  
Alexandra Navrotsky
Keyword(s):  
High Temperature ◽  
Solution Calorimetry ◽  
Block Element ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide ◽  
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