Standard enthalpies of formation of some borides of Ce, Pr, Nd and Gd by high-temperature reaction calorimetry
1995; Elsevier BV; Volume: 221; Issue: 1-2 Linguagem: Inglês
10.1016/0925-8388(94)01437-x
ISSN1873-4669
Autores Tópico(s)Intermetallics and Advanced Alloy Properties
ResumoThe standard enthalpies of formation of five lanthanide borides have been determined calorimetrically at 1473 ± 2 K. The following values of ΔHf0 are reported: PrB6, − 51.3 ± 5.7 kJ/g · atom (this value was determined by solute-solvent drop calorimetry); CeB4, − 53.5 ± 1.5 kJ/g · atom; PrB4, − 53.1 ± 1.6 kJ/g · atom; NdB4, − 53.3 ± 1.5 kJ/g · atom; Gd2B5, − 43.1 ± 1.4 kJ/g · atom (these four values were all obtained by direct synthesis calorimetry from the elements). The results are compared with earlier experimental data and with values predicted from Miedema's semi-empirical model. Finally, a systematic comparison is presented between the considered boride data and values for compounds of the rare-earth metals with Al, Ga, In and Tl taken from the published literature.
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