Valence states of Yb inYb5Si3

Thermochemistry of ytterbium silicides

“…Relevant data for the elements were taken from Hultgren's reference compilation [13]. In a recent paper Dhar et al [9] reported the heat capacities for the new phases Si 4 Yb 5 and Si 4 Yb 3 in the low-temperature range 1-30 K. A tentative extrapolation of these data to 300 K using both the Nernst-Lindemann [14] 4 and S o 298 (Tarasov)=54.7 J K À1 mol atoms À1 ]. Due to the limited temperature range for which experimental data are available no reliable extrapolation above 300 K could be performed.…”

“…As pointed out by Miedema [18] attention should be paid in applying this model to Yb alloys, because of the fluctuant valence state of this element. Several researches have been devoted to the study of the fluctuations of the Yb valence in four out of six Si-Yb phases (Si 3 Yb 5 , SiYb, Si 5 Yb 3 and Si 1.74 Yb) [1][2][3][4]: in these compounds both divalent and trivalent Yb atoms are present, depending on the crystal site. The average valence states of Yb were taken from the literature as follows: 3 (Si 3 Yb 5 ) [4], 2.72 (SiYb) [2], 2.52 (Si 5 Yb 3 ) [2] and 2.35 (Si 1.74 Yb) [1].…”

“…Several researches have been devoted to the study of the fluctuations of the Yb valence in four out of six Si-Yb phases (Si 3 Yb 5 , SiYb, Si 5 Yb 3 and Si 1.74 Yb) [1][2][3][4]: in these compounds both divalent and trivalent Yb atoms are present, depending on the crystal site. The average valence states of Yb were taken from the literature as follows: 3 (Si 3 Yb 5 ) [4], 2.72 (SiYb) [2], 2.52 (Si 5 Yb 3 ) [2] and 2.35 (Si 1.74 Yb) [1]. The D f H 298 predicted by Miedema's model are reported in Table 3: these formation enthalpies have been derived as the weighted average between those calculated using divalent and trivalent Yb parameters [17].…”

“…as high temperature structural materials and contact materials in microelectronics. This interest is even higher for the Si-Yb intermediate phases where Yb mixed valence fluctuations can be observed between bulk silicides and their surfaces [1][2][3][4]. The modelling of solid-state siliconmetal interaction, interface formation, etc.…”

Binary intermetallic phases formed by Ca, Sr, Ba, Eu and Yb: similarities and differences

“…The magnetic behaviour indicates a completely trivalent state in YbSi [54] and YbAu 2 [55], and a prevailing trivalency in YbPd [56], Yb 3 Si 4 [57] and Yb 5 Si 3 [58,59]. The cell volume of YbAs lies on the linear trend shown by the RAs compounds formed by the heavy rare earths (R ¼ Gd to Lu), while the point of Yb 5 Ge 3 is slightly higher than the corresponding trend of the R 5 Ge 3 phases.…”