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A thermodynamic study of the cadmium-neodymium system.

Skołyszewska-Kühberger B, Reichmann TL, Ipser H - Monatsh. Chem. (2016)

Bottom Line: With these partial molar enthalpies, the Cd activities were converted to a common temperature of 873 K.By means of a Gibbs-Duhem integration Nd activities and integral Gibbs energies were calculated, using a literature value of Δf G for the phase Cd6Nd as integration constant.A minimum of Δf G ≈ -38 kJ g-atom(-1) at 873 K was obtained for the phase CdNd, a value that compares well with other CdRE compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Inorganic Chemistry (Materials Chemistry), University of Vienna, 1090 Vienna, Austria.

ABSTRACT

Abstract: Cd vapor pressures were determined over Cd-Nd samples by an isopiestic method. The measurements were carried out in the temperature range from about 690 to 1200 K and over a composition range between 48 and 92 at % Cd. From the vapor pressures, thermodynamic activities of Cd were derived for all samples at their respective sample temperatures, and partial molar enthalpies of Cd were obtained from the temperature dependence of the activities. With these partial molar enthalpies, the Cd activities were converted to a common temperature of 873 K. By means of a Gibbs-Duhem integration Nd activities and integral Gibbs energies were calculated, using a literature value of Δf G for the phase Cd6Nd as integration constant. A minimum of Δf G ≈ -38 kJ g-atom(-1) at 873 K was obtained for the phase CdNd, a value that compares well with other CdRE compounds.

No MeSH data available.


Related in: MedlinePlus

Natural logarithm of the Cd activity in the Cd–Nd system at 873 K; standard state: Cd(l)
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Fig4: Natural logarithm of the Cd activity in the Cd–Nd system at 873 K; standard state: Cd(l)

Mentions: The majority of the samples were single phase, namely CdNd, Cd2Nd, Cd45Nd11, and Cd6Nd. As in several other RE-Cd systems [21–23], no single phase samples of Cd3Nd could be obtained in any of the runs suggesting that Cd3Nd is only slightly more stable than a two-phase mixture of its neighboring compounds. Thus, the activities of Cd in the adjacent two-phase fields Cd2Nd + Cd3Nd and Cd3Nd + Cd45Nd11 are only slightly different (cf. Fig. 4). Moreover, it was found that a majority of data points fall into the composition range of the phase Cd2Nd indicating that this must be one of the relatively most stable compounds in the Cd–Nd system, in agreement with its congruent formation from the liquid [15].


A thermodynamic study of the cadmium-neodymium system.

Skołyszewska-Kühberger B, Reichmann TL, Ipser H - Monatsh. Chem. (2016)

Natural logarithm of the Cd activity in the Cd–Nd system at 873 K; standard state: Cd(l)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4863036&req=5

Fig4: Natural logarithm of the Cd activity in the Cd–Nd system at 873 K; standard state: Cd(l)
Mentions: The majority of the samples were single phase, namely CdNd, Cd2Nd, Cd45Nd11, and Cd6Nd. As in several other RE-Cd systems [21–23], no single phase samples of Cd3Nd could be obtained in any of the runs suggesting that Cd3Nd is only slightly more stable than a two-phase mixture of its neighboring compounds. Thus, the activities of Cd in the adjacent two-phase fields Cd2Nd + Cd3Nd and Cd3Nd + Cd45Nd11 are only slightly different (cf. Fig. 4). Moreover, it was found that a majority of data points fall into the composition range of the phase Cd2Nd indicating that this must be one of the relatively most stable compounds in the Cd–Nd system, in agreement with its congruent formation from the liquid [15].

Bottom Line: With these partial molar enthalpies, the Cd activities were converted to a common temperature of 873 K.By means of a Gibbs-Duhem integration Nd activities and integral Gibbs energies were calculated, using a literature value of Δf G for the phase Cd6Nd as integration constant.A minimum of Δf G ≈ -38 kJ g-atom(-1) at 873 K was obtained for the phase CdNd, a value that compares well with other CdRE compounds.

View Article: PubMed Central - PubMed

Affiliation: Department of Inorganic Chemistry (Materials Chemistry), University of Vienna, 1090 Vienna, Austria.

ABSTRACT

Abstract: Cd vapor pressures were determined over Cd-Nd samples by an isopiestic method. The measurements were carried out in the temperature range from about 690 to 1200 K and over a composition range between 48 and 92 at % Cd. From the vapor pressures, thermodynamic activities of Cd were derived for all samples at their respective sample temperatures, and partial molar enthalpies of Cd were obtained from the temperature dependence of the activities. With these partial molar enthalpies, the Cd activities were converted to a common temperature of 873 K. By means of a Gibbs-Duhem integration Nd activities and integral Gibbs energies were calculated, using a literature value of Δf G for the phase Cd6Nd as integration constant. A minimum of Δf G ≈ -38 kJ g-atom(-1) at 873 K was obtained for the phase CdNd, a value that compares well with other CdRE compounds.

No MeSH data available.


Related in: MedlinePlus