Influence of connectivity on the rigidity of the covalently bonded (GeTe4)100−x(As2Se3)x glasses

Evaluating Ovonic Threshold Switching Materials with Topological Constraint Theory

“… It should be noted that this peak may also have contributions due to a defective octahedral GeTe 4 structural unit . Previous experiments on various related material systems assign peaks near 200 and 240 cm –1 to GeSe 4 , AsSe 3 , and AsTe 3 structural units. ,,,,,, Our simulations indicate that the small peak at 280 cm –1 may be due to vibrations of Se atoms linking two GeSe 4 tetrahedra.…”

“…Raman peaks on the same frequency range have been observed in Ge 0.20 Te x Se 0.80– x alloys and AsSeTe alloys, so it is probable that both contribute. Other studies have also assigned the peak near 180 cm –1 to structural units related to GeTe 4 and AsTe 3 It should be noted that this peak may also have contributions due to a defective octahedral GeTe 4 structural unit .…”

Structure–property relationships in critically connected (GeTe4)100−x(As2Se3)x glasses

“…For a lower content of As 2 Se 3 , the Raman bands observed at 123 cm −1 and 157 cm −1 correspond to GeTe 4 and Te-Te vibrations. 34,35 In region II, new bands at 140, 169 and 195 cm −1 are observed, mainly characteristic of AsTe (3/2) , Se-Te and GeSe tetrahedral structures. 16,36,37 At higher concentrations of As 2 Se 3 , Raman bands at 167, 194 and 229 cm −1 are observed and are characteristic of As-Se based vibrational units.…”

“…4 have been prepared by a melt quenching technique. The activation energy of crystallization is observed to be minimum in region II (x =[30][31][32][33][34][35][36][37][38][39][40], which indicates that less energy is required by the material to change its state from amorphous to crystallization. The kinetic fragility shows variation between 13 and 50 indicating that all these glasses are kinetically strong except for x = 0 for which the fragility index is 50.…”

Investigation of the acousto‐optical properties of Ge–As–Te–(Se) chalcogenide glasses at 10.6 μm wavelength

“…50 Ge-Se bond (49.1 kcal/mol), Te-Se (44.2 kcal/mol), Se-Se (44 kcal/ mol), and As-Se bonds (41.69 kcal/mol) are generated in the order of reducing bond energies when Te element is replaced by Se element. 51 The increase in total bond energy leads to an increase in T g and T x . Since [GeSe 4 ] tetrahedron is more stable than [GeTe 4 ] tetrahedron, Ge 10 As 20 Te 70−y Se y glass has better rigidity and elastic properties than Ge 10 As 90−x Te x .…”