Anomalous X-Ray Scattering Studies on Glassy GexSe1−x across the Stiffness Threshold Composition x = 0.20

Abstract

Anomalous x-ray scattering experiments on glassy Ge x Se 1−x have been carried out at energies close to the Ge and Se K edges at concentrations close to the onset-and at the mid-point of the rigidity percolation threshold (x = 0.195 and 0.23). The total structure factors S(Q) show rapid variations in both the position and intensity of the prepeak around 11 nm −1 , while it stays almost unchanged in the remaining Q range. The differential structure factors ∆ i S(Q) comprise characteristic features. Comparing them suggests that the prepeak purely originates from the Ge-Ge correlation. The present structural results strongly support the chemically-ordered continuous-random-network model for the Ge-Se glasses. The origin of the prepeak was discussed from a comparison between the S GeGe (Q) of g-GeSe 2 obtained by Petri et al. and S(Q) of a-Ge. The concentration dependence of the prepeak is consistent with the Raman data, which reveal the diminishing of short Se chain connections between the Ge(Se 1/2 ) 4 tetrahedra near the stiffness transition composition.

Does the 8-N bonding rule break down in As 2 Se 3 glass?

“…Following the procedure given in Ref. [10], differential structure factors, ∆ k S(Q), were obtained from the difference between diffraction data with two different incident x-ray energies near each K edge of k element.…”

Partial structure of Pd42:5Ni7:5Cu30P20bulk metallic glass

“…[8], ∆ i S(Q) were calculated from the scattering data. For each ∆ i S(Q), the corresponding i-th edge element related partial structure factors, S ij (Q), dominates ∆ i S(Q).…”

Local Structure around Pd Atoms in Pd<SUB>42.5</SUB>Ni<SUB>7.5</SUB>Cu<SUB>30</SUB>P<SUB>20</SUB> Excellent Glass-Former Studied by Anomalous X-ray Scattering

“…8) Following the procedure given in Ref. 9), Á Pd SðQÞ was calculated from the scattering data. The large contributions of S ij ðQÞ (more than 0.05) to the Á Pd SðQÞ and SðQÞ in Pd 42:5 Ni 7:5 Cu 30 P 20 alloy at the first maximum around 29 nm À1 in SðQÞ are tabulated in Table 1.…”