High-temperature behavior and thermodynamic properties of the compounds Cu3P and CuP2

The Thermodynamic Properties of Phosphorus and Solid Binary Phosphides

“…The partial pressure of P 4 in equilibrium with CuP 2 and Cu 3 P has been measured by Haraldsen (873-1073 K) and by Ugai et al (963-1173 K) 133,222 using static method techniques; the agreement between the results is impressive. Combining the two results, for In addition to this, Gordienko and Viksman reported the partial pressure of P 4 generated by the decomposition of Cu 3 P. 221 However, the temperatures at which values are reported (1178, 1238, and 1292 K) are higher than the Cu/Cu 3 P eutectic in Figure 17, making the data unusable for calculating assessed thermodynamic properties for Cu 3 P (and thus for CuP 2 as well). No reported thermodynamic data are available for Cu 2 P 7 .…”

“…No lowtemperature heat capacity measurements have been made in the system, but high-temperature heat capacities were measured for Cu 3 P (298-1295 K) and CuP 2 (298-1164 K) by Gordienko and Viksman. 221 Two experimental determinations of ∆H°(red (I) reference state) were also made for Cu 3 P, using direct reaction calorimetry: Weibke and Schrag 46 reported a value of -133.9 kJ/mol at 903 K, and Boone and Kleppa 34 determined a value of -166.1 kJ/mol at 298 K. The unusual temperature used by Weibke and Schrag (discussed previously), along with other concerns over the accuracy of their calorimeter, 34 recommends the results of Boone and Kleppa as more accurate.…”

“…For the reaction, For the reaction, On the basis of these equations, second-law calculations can be made of the enthalpies and Gibbs energies of formation of AgP 2 and Au 2 P 3 ; these are listed in Table 36. It should be noted that eq 85 generates a unit-pressure decomposition temperature 4 Elliott and Gleiser 6 Kubaschewski et al 121 Myers et al 224 Boone and Kleppa 34 Weibke and Schrag 46 Karakaya and Thompson 228 Gordienko and Viksman 221 an Mey and The vapor pressure measurements by Haraldsen and Biltz also include measurement of the partial pressure of P 4 in equilibrium with AgP 2 and a phase identified as "AgP 3 ", which likely has the actual stoichiometry Ag 3 P 11 . 3 If the latter stoichiometry is used, for the reaction, This allows second-law calculation of thermodynamic values for Ag 3 P 11 , also shown in Table 36.…”

“…Of the three elements in this group, the most thermodynamic information exists for the Cu−P system, research interest being driven by the use of phosphorus in commercial copper alloys. No low-temperature heat capacity measurements have been made in the system, but high-temperature heat capacities were measured for Cu 3 P (298−1295 K) and CuP 2 (298−1164 K) by Gordienko and Viksman recommends the results of Boone and Kleppa as more accurate.…”

Semiconductor thermochemistry in density functional calculations

“…The elemental reference energies are then obtained by solving a set of linear equations, using as input the DFTcalculated total energies of the compounds and the experimental heats of formation. [10][11][12][13][14][15][16][17][18][19][20][21][22][23] The elemental reference energies that are found to minimize the root-mean-square ͑rms͒ deviation from the experimental heats of formation imply corrections up to 1 eV compared to the directly calculated LDA or GGA energies of the respective elements. Further, in compounds containing metals with shallow d states it is often desirable to use the LDA+ U or GGA+ U methodology 24 to correct for residual self-interaction effects within the cation d shell, e.g., in systems containing transition metals, 4,[25][26][27] or when shallow d states couple strongly to the valence band in semiconductors, as is the case in the photovoltaic chalcopyrites CuInSe 2 and CuGaSe 2 , 28 in Cu 2 O, 29,30 or in II-VI semiconductors such as ZnO.…”