Thermodynamic investigation of the systems LnSe2–LnSe1.5 (Ln = La, Nd)

Thermodynamic investigation of the phase formation processes in the systems LnSe2–LnSe1.5 (Ln=La, Ce, Pr, Nd)

“…At that time we had not enough data for detecting PrSe 1.95 phase. But as far as LnSe 1.95 phase exists in the systems La-Se, Nd-Se [11] and Ce-Se, one more experiment was carried out for revealing this phase in the Pr-Se system. Data obtained together with data from [10] (figure 3a and b) prove the existence of PrSe 1.95 phase.…”

“…In our previous works [10,11], we had estimated of entropies and heat capacities of all selenides from the dependence of properties on the molar mass, taking into account C°p and S°both the lower (LnSe and LnSe 1.5 ) and the higher (LnSe 1.5 ) selenides. According to [22], the dependences of heat capacity (or entropy) of selenides from their molar mass were constructed.…”

“…Smoothed values of C p and S, including for one-and-a-half selenides, were taken at determining the thermodynamic characteristics of LnSe x dissociation. These values were listed in tables within [10,11].…”

“…Therefore we arrived at a conclusion that the estimation of the properties according to the equation (8) is more correct decision. For this reason, values from [22] were adjusted slightly and the results in [10,11] were recalculated in this work using the new technique of C°p and S°estimation.…”

“…Earlier we investigated the systems LnSe 2Àx -LnSe 1.5 (Ln = La, Nd, Pr, Gd) [10,11], where the intermediate individual phases LnSe 1.95 (Ln = La, Nd), LnSe 1.85 (Ln = La, Pr, Nd, Gd), LnSe 1.80 (Ln = La, Pr, Nd, Gd) and GdSe 1.71 were detected for the first time. The aim of this work is to obtain the reliable data on compositions and homogeneity regions of intermediate phases in the LnSe 2 -LnSe 1.5 (Ln = Ce, Pr) systems, calculate the thermodynamics of the dissociation processes and analyse the thermodynamic properties of light (La, Ce, Pr, Nd) rare-earth polyselenides as a function of the selenium content.…”