Enthalpies of formation of CdSxSe1–x solid solutions

2009 ◽  
Vol 24 (4) ◽  
pp. 1368-1374 ◽  
Author(s):  
Fen Xu ◽  
Xuchu Ma ◽  
Susan M. Kauzlarich ◽  
Alexandra Navrotsky
Keyword(s):  
Solid Solution ◽  
Thermodynamic Properties ◽  
Molar Volume ◽  
Solid Solutions ◽  
Calorimetric Method ◽  
Molar Ratio ◽  
Enthalpies Of Formation ◽  
Size Difference ◽  
Experimental Errors ◽  
End Members

The enthalpies of oxidative drop solution (ΔHds) for a series of CdSxSe1–x samples were obtained by calorimetry in molten 3Na2O·4MoO3 at 975 K. They become more exothermic linearly with increasing S content. The enthalpies of formation from the elements (ΔHf,el) depend linearly on molar ratio of S/(S + Se). This is the first report of thermodynamic properties of CdSxSe1–x solid solutions measured by any direct calorimetric method. The enthalpies of formation at 298 K from the binary chalcogenide end-members (ΔHf,CdM) (M = S, Se) for wurtzite CdSxSe1–x are found to be zero within experimental errors. These results strongly suggest that wurtzite CdS and CdSe form an ideal solid solution, despite a substantial difference in molar volume and anion radius. This implies that size difference affects thermodynamics less strongly when larger and more polarizable anions are mixed in chalcogenides than when cations are mixed in oxides.

scholarly journals The solid solutions of rebulite and jankovićite in the phase system Tl2S-As2S3-Sb2S3

2015 ◽  
Vol 34 (1) ◽  
pp. 125
Author(s):  
Tonci Balic-Zunic ◽  
Yves Moëlo ◽  
Ljiljana Karanović ◽  
Peter Berlepsch
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Solid Solutions ◽  
Unit Cell ◽  
Phase System ◽  
Structural Topology ◽  
Coordination Polyhedra ◽  
Ideal Composition ◽  
End Members ◽  
Compositional Line

Syntheses along the Tl<sub>5</sub>(As,Sb)<sub>13</sub>S<sub>22</sub> compositional line in the Tl<sub>2</sub>S-As<sub>2</sub>S<sub>3</sub>-Sb<sub>2</sub>S<sub>3</sub> phase system showed that the compositional range of rebulite extends from  Tl<sub>5</sub>As<sub>9.5</sub>Sb<sub>3.5</sub>S<sub>22</sub> to Tl<sub>5</sub>As<sub>7.75</sub>Sb<sub>5.25</sub>S<sub>22</sub>. The Sb-rich end-member is in equilibrium with jankovićite of ideal composition Tl<sub>5</sub>Sb<sub>7.5</sub>As<sub>5.5</sub>S<sub>22</sub>. It is considered to be the As-rich end-member of the jankovićite solid solution. The crystal structure analyses of crystals from the As and Sb end-members of rebulite show that the Sb/As substitution is present in Sb3, Sb4, Sb5, As1 and As2 structural sites. Of them, Sb3 is always Sb dominated whereas other four vary from As- to Sb-dominated over the range of the solid solution. The change of the structural topology from jankovićite to rebulite, the closely related but not identical structures, is explained through necessity to accommodate the smaller volumes of the As coordination polyhedra and is accomplished through unit-cell twinning over the periodic (001)<sub>reb</sub> twin boundaries. The As end-member of the rebulite solid solution is in equilibrium with the phase of Tl<sub>2.4</sub>Sb<sub>0.68</sub>As<sub>7.18</sub>S<sub>13</sub> ideal composition, interpreted as imhofite.

True and brittle micas: composition and solid-solution series

2007 ◽  
Vol 71 (3) ◽  
pp. 285-320 ◽  
Author(s):  
G. Tischendorf ◽  
H.-J. Förster ◽  
B. Gottesmann ◽  
M. Rieder
Keyword(s):  
Solid Solution ◽  
Crystal Structures ◽  
Solid Solutions ◽  
Solid Solution Series ◽  
Octahedral Sheet ◽  
Tetrahedral Sheet ◽  
Solution Series ◽  
The Common ◽  
End Members ◽  
Graphical Presentation

AbstractMicas incorporate a wide variety of elements in their crystal structures. Elements occurring in significant concentrations in micas include: Si, IVAl, IVFe3+, B and Be in the tetrahedral sheet; Ti, VIAl, VIFe3+, Mn3+, Cr, V, Fe2+, Mn2+, Mg and Li in the octahedral sheet; K, Na, Rb, Cs, NH4, Ca and Ba in the interlayer; and O, OH, F, Cl and S as anions. Extensive substitutions within these groups of elements form compositionally varied micas as members of different solid-solution series. The most common true K micas (94% of almost 6750 mica analyses) belong to three dominant solid-solution series (phlogopite–annite, siderophyllite–polylithionite and muscovite–celadonite). Theirclassification parameters include: Mg/(Mg+Fetot) [=Mg#] formicas with VIR >2.5 a.p.f.u. and VIAl <0.5 a.p.f.u.; Fetot/(Fetot+Li) [=Fe#] formicas with VIR >2.5 a.p.f.u. and VIAl >0.5 a.p.f.u.; and VIAl/(VIAl+Fetot+Mg) [=Al#] formicas with VIR <2.5 a.p.f.u. The common true K micas plot predominantly within and between these series and have Mg6Li <0.3 a.p.f.u. Tainiolite is a mica with Mg6Li >0.7 a.p.f.u., or, fortr ansitional stages, 0.3–0.7 a.p.f.u. Some true K mica end-members, especially phlogopite, annite and muscovite, form binary solid solutions with non-K true micas and with brittle micas (6% of the micas studied). Graphical presentation of true K micas using the coordinates Mg minus Li (= mgli) and VIFetot+Mn+Ti minus VIAl (= feal) depends on theirclassification according to VIR and VIAl, complemented with the 50/50 rule.

An ideal solid solution model for calculating solubility of clay minerals

Clay Minerals ◽  
1981 ◽  
Vol 16 (4) ◽  
pp. 361-373 ◽  
Author(s):  
Y. Tardy ◽  
B. Fritz
Keyword(s):  
Solid Solution ◽  
Clay Minerals ◽  
Chemical Evolution ◽  
Solid Solutions ◽  
Natural Water ◽  
Free Energies ◽  
Natural Clay ◽  
Data Set ◽  
Solubility Products ◽  
End Members

AbstractA method for estimating Gibbs free energies and stabilities of clay minerals is proposed for use with computer programs aimed at calculating the chemical evolution of natural water-rock systems. This is based on (i) a model for ideal solid solutions of a large number of end-member compositions and (ii) a data set of estimated solubility products from 36 end-members. The application of the method to the production of experimental or natural clay stabilities is discussed.

Monazite end members and solid solutions: synthesis, unit-cell characteristics, and utilization as microprobe standards

1989 ◽  
Vol 53 (369) ◽  
pp. 120-123 ◽  
Author(s):  
J. M. Montel ◽  
F. Lhote ◽  
J. M. Claude
Keyword(s):  
Solid Solution ◽  
Experimental Study ◽  
Solid Solutions ◽  
Unit Cell ◽  
Solid Solution Series ◽  
Solution Series ◽  
End Members ◽  
Characteristics And Utilization

The synthesis of monazite was first reported by Radominsky (1875). Since then various methods have been used to synthesize various end members of the monazite solid solution series, mainly CePO4 and LaPO4 (e.g. Anthony, 1957, 1965). As part of an experimental study dealing with the solubility of monazite in granitic melts (Montel, 1986, 1987, and in prep.), the synthesis of some of the end members, as well as solid solutions, was achieved.

Energetics of rare-earth-doped hafnia

2007 ◽  
Vol 22 (4) ◽  
pp. 876-885 ◽  
Author(s):  
Petra Simoncic ◽  
Alexandra Navrotsky
Keyword(s):  
Rare Earth ◽  
Solid Solutions ◽  
Energy Difference ◽  
Solution Calorimetry ◽  
Interaction Parameters ◽  
Enthalpies Of Formation ◽  
Amorphous Phases ◽  
Oxide Melt ◽  
Local Structures ◽  
End Members

The enthalpies of formation of rare-earth (RE)-doped Hf1−xRExO2−x/2 solid solutions (RE = Sm, Gd, Dy, Yb; x = 0.25 to 0.62) with respect to the oxide end members, monoclinic HfO2 and C-type REO1.5, were determined using oxide melt solution calorimetry. The enthalpies of formation fit a function quadratic in composition. The strongly negative interaction parameters in all solid solutions confirm a strong tendency for short-range order. Though strongly negative for all systems, the interaction parameters become less negative with increasing ionic potential (decreasing RE radius). Crystallization energetics were investigated for amorphous coprecipitation products with x = 0.4. The energy difference between the crystalline (fluorite and pyrochlore) and amorphous phases decreases with decreasing dopant radius. This suggests that systems doped with small RE ions have more similar local structures in the fluorite and amorphous phases. These observations may result in a smaller kinetic barrier to recrystallization and account for the greater radiation resistance of materials with smaller RE cations.

Preliminary Evaluation of Thermodynamic Mixing Properties and Miscibility Limits for Cubic Dioxide (Zr, M)O2 and Zircon (Zr, M)SiO4 Solid Solutions (M = An4+, Ln4+)

1997 ◽  
Vol 506 ◽  
Author(s):  
V.A. Kurepin
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Enthalpy Of Mixing ◽  
Thermodynamic Theory ◽  
Preliminary Evaluation ◽  
Interatomic Distances ◽  
Mixing Properties ◽  
Equilibrium Data ◽  
End Members ◽  
The Relationship

Cubic zirconia ZrO2 and zircon ZrSiO4 are considered as perspective crystalline form for immobilization of U, Pu and other radionuclides [1, 2]. The present study was undertaken to determine temperature dependence of solid solution limits in these compounds using thermodynamic theory of solid solutions and available equilibrium data. Thermodynamic mixing properties has been evaluated by means of the relationship between Margules parameter W and interatomic distances R in end-members AX and BX of a solid solution (A1−xBx)XW = α(ΔR/R)2where ΔR = R(BX) - R(AX), R = (1−x) R(AX) + x R(BX), α is a constant for isotypic isostructural compounds. According to the Urusov's energetic theory of enthalpy of mixing [3] such relationships exist between parameters W, AR and R of solid solutions with similar bonds between isomorphous atoms and their neighbors

Thermodynamics and solubility of (UxNp1-x)O2(am) solid solution in the carbonate system

2004 ◽  
Vol 92 (9-11) ◽  
Author(s):  
Dhanpat Rai ◽  
Nancy J. Hess ◽  
M. Yui ◽  
Andrew R. Felmy ◽  
D. A. Moore
Keyword(s):  
Solid Solution ◽  
Thermodynamic Properties ◽  
Solid Solutions ◽  
Minor Component ◽  
Carbonate System ◽  
A Minor

SummaryThe formation of a solid solution can significantly affect the solubility of a minor component. The objectives of this study were to determine the nature of U(IV) and Np(IV) solid solutions and their thermodynamic properties. For this purpose, (U

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