Natural kaersutite: ftir, raman, thermal and thermochemical investigations

A thermochemical study of the natural oxo-amphibole ─ kaersutite Na0.4K0.3(Ca1.6Na0.4)(Mg2.9Fe0.82+Al0.7Ti0.6Fe0.53+)[Si6.1Al1.9O22](OH)0.2O1.8.(alkaline basalts of Mongolia) was performed on a Tian-Calvet microcalorimeter. The enthalpy of formation from the elements ∆fH el0(298.15 K) = – 12102 ± 16 kJ/mol) was obtained by the method of high-temperature melt solution calorimetry. The entropy, enthalpy and Gibbs energy of the formation of the end-members of the isomorphic series kaersutite NaCa2Mg3TiAl[Si6Al2O22]O2 – ferri-kaersutite NaCa2Mg3TiFe3+[Si6Al2O22]O2 were estimated.

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Thermodynamic properties of montechellite

Геохимия ◽

10.31857/s0016-752564121274-1280 ◽

2019 ◽

Vol 64 (12) ◽

pp. 1274-1280

Author(s):

L. P. Ogorodova ◽

Yu. D. Gritsenko ◽

M. F. Vigasina ◽

A. Yu. Bychkov ◽

D. A. Ksenofontov ◽

...

Keyword(s):

High Temperature ◽

Gibbs Energy ◽

Solution Calorimetry ◽

Thermochemical Study ◽

Gibbs Energy Of Formation ◽

Calvet Microcalorimeter ◽

Magnesium Orthosilicate ◽

Calcium And Magnesium ◽

The Enthalpy Of Formation ◽

Energy Of Formation

A thermochemical study of natural calcium and magnesium orthosilicate ─ monticellite (Ca1.00Mg0.95)[SiO4] (Khabarovsk Territory, Russia) was carried out on the Tian-Calvet microcalorimeter. The enthalpy of formation from the elements fHоel(298.15 K) = -2238.4 4.5 kJ / mol was determined by the method of high-temperature melt solution calorimetry. The enthalpy and Gibbs energy of formation of monticellite of the theoretical composition of CaMg[SiO4] are calculated: fH0el(298.15 K) = -2248.4 4.5 kJ/mol and fG0el(298.15 K) = -2130.5 4.5 kJ/mol.

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Thermochemical study of sodium and sodium-calcium amphibols

Геохимия ◽

10.31857/s0016-7525645520-528 ◽

2019 ◽

Vol 64 (5) ◽

pp. 520-528

Author(s):

L. P. Ogorodova ◽

I. A. Kiseleva ◽

M. F. Vigasina ◽

Yu. D. Gritsenko ◽

I. A. Bryzgalov ◽

...

Keyword(s):

Kola Peninsula ◽

Solution Calorimetry ◽

Enthalpies Of Formation ◽

Thermochemical Study ◽

Massif Central ◽

Calvet Microcalorimeter ◽

Gibbs Energies ◽

Sodium Calcium ◽

Isomorphic Series ◽

End Members

A thermochemical study of six natural sodium and sodium-calcium amphiboles was carried out using the high-temperature melt solution calorimetry on a Tian-Calvet microcalorimeter. The enthalpies of formation from the elements have been obtained for arfvedsonites: K0.5(Na1.5Ca0.5)(Mg4.0Fe0.93+Al0.1)[Si8.0O22](OH)2 (Inaglinsky Massif, Central Aldan, Russia) (-11626.6 ± 8.9 kJ/mol), (Na0.5K0.1)(Na1.6Ca0.4)(Mg3.6Fe0.42+Fe0.83+Al0.2)[Si8.0O22](OH)2 (Khibiny Massif, Kola Peninsula, Russia) (-11520.8 ± 14.6 kJ/mol) and (Na0.7K0.3)Na2.0(Fe4.02+Fe0.63+Mn0.1Ti0.1Al0.2)[Si8.0O22](OH)2 (Katuginskoe deposit, Transbaikalia, Russia) (-11384.7 ± 17.1 kJ/mol); for riebeckites: Na2.0(Mg2.5Fe0.52+Fe1.53+Al0.5)Si8O22(OH)2 (Kumula deposit, Central Kazakhstan) (-10791.0 ± 10.1 kJ/mol) and Na2.0(Mg0.9Fe2.12+Fe1.93+Al0.1)[Si8O22](OH)2 (Krivoy Rog, Ukraine) (-10260.8 ± 10.9 kJ/mol) and richterite (Na0.7K0.3)(Ca1.2Na0.8)(Mg4.6Fe0.42+)[Si7.8Al0.2O22](OH)2 (Kovdorsky Massif, Kola Peninsula, Russia) (-12154.2 ± 9.7 kJ/mol). The values of the standard entropies, enthalpies, and Gibbs energies of formation are estimated for the end members of isomorphic series: arfvedsonite – magnesioarfvedsonite, riebeckite – magnesioriebeckite and richterite – ferrochichthite.

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

Journal of Materials Research ◽

10.1557/jmr.2003.0348 ◽

2003 ◽

Vol 18 (10) ◽

pp. 2501-2508 ◽

Cited By ~ 49

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.

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Enthalpy of Formation of Rare-earth Silicates Y2SiO5 and Yb2SiO5 and N-containing Silicate Y10(SiO4)6N2

Journal of Materials Research ◽

10.1557/jmr.1999.0158 ◽

1999 ◽

Vol 14 (4) ◽

pp. 1181-1185 ◽

Cited By ~ 37

Author(s):

Jian-Jie Liang ◽

Alexandra Navrotsky ◽

Thomas Ludwig ◽

Hans J. Seifert ◽

Fritz Aldinger

Keyword(s):

Rare Earth ◽

High Temperature ◽

Enthalpy Of Formation ◽

Temperature Drop ◽

Solution Calorimetry ◽

Enthalpies Of Formation ◽

Binary Oxides ◽

Standard Enthalpies Of Formation ◽

Oxygen Gas ◽

The Enthalpy Of Formation

The enthalpies of formation of two rare-earth silicates (Y2SiO5 and Yb2SiO5) and a N-containing rare-earth silicate Y10(SiO4)6N2 have been determined using high-temperature drop solution calorimetry. Alkali borate (52 wt% LiBO2·48 wt% NaBO2) solvent was used at 800 °C, and oxygen gas was bubbled through the melt. The nitrogen-containing silicate was oxidized during dissolution. The standard enthalpies of formation are for Y2SiO5, Yb2SiO5, and Y10(SiO4)6N2, respectively, –22868.54 ± 5.34, –22774.75 ± 8.21, and –14145.20 ± 16.48 kJ/mol from elements, and –52.53 ± 4.83, –49.45 6 ± 8.35, and –94.53 ± 11.66 kJ/mol from oxides (Y2O3 or Yb2O3, SiO2) and nitride (Si3N4). The silicates and N-containing silicate are energetically stable with respect to binary oxides and Si3N4, but the N-containing silicate may be metastable with respect to assemblages containing Y2SiO5, Si3N4, and SiO2. A linear relationship was found between the enthalpy of formation of a series of M2SiO5 silicates from binary oxides and the ionic potential (z/r) of the metal cation.

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

Journal of Materials Research ◽

10.1557/jmr.1999.0264 ◽

1999 ◽

Vol 14 (5) ◽

pp. 1959-1968 ◽

Cited By ~ 44

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.

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Thermochemistry of lanthanum zirconate pyrochlore

Journal of Materials Research ◽

10.1557/jmr.2009.0401 ◽

2009 ◽

Vol 24 (11) ◽

pp. 3350-3357 ◽

Cited By ~ 55

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.

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Formation Enthalpy, Free-Energy and Activity Coefficients of Sn-Pb Eutectic Solders

Materials Science Forum ◽

10.4028/www.scientific.net/msf.610-613.531 ◽

2009 ◽

Vol 610-613 ◽

pp. 531-536 ◽

Cited By ~ 4

Author(s):

Gui Sheng Gan ◽

Fang Chen ◽

Rong Chang Zeng ◽

Yun Fei Du ◽

Chang Hua Du

Keyword(s):

Free Energy ◽

High Temperature ◽

Enthalpy Of Formation ◽

Activity Coefficients ◽

Excess Free Energy ◽

Formation Enthalpy ◽

Chemical Activity ◽

Lead Pollution ◽

The Relationship ◽

The Enthalpy Of Formation

Based on Miedema’s model, the enthalpy of formation, excess free-energy and partial molar excess free-energy of Sn-Pb binary alloy solders were calculated. The model of the activity coefficient for each component in the solders was established. The diagrams of enthalpy of formation, free energy versus composition and activity versus composition and temperature as well as activity coefficients as a function of composition and/or temperature were drawn. And then the relationship between the activity coefficients of elements Sn/Pb in the solders and temperature was obtained. The approaches to reduction in the volatilization of lead at high temperature were proposed from the point of views that the lead pollution to environment results from its chemical activity in the solder alloys.

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