The structural and spectroscopic investigations of ternary tellurite glasses, doped with copper

Theoretical investigations of the spin Hamiltonian parameters and local tetragonal distortions for Cu2+in crystalline and amorphous TeO2and GeO2

“…In essence, the impurity may occupy suitable octahedral sites (e.g., the octahedral interstitial sites) capacious enough to accommodate it without breaking local stability for very low copper concentration (≈ 0.1% mol) at low temperature (77 K). Judging from the experimental EPR data [14,15] of the studied systems, the averageḡ ∼ 2.1 and the anisotropies (g // > g ⊥ > 2 and |A // | > |A ⊥ |) for g factors and hyperfine structure constants definitely indicate the impurity Cu 2 + occupying tetragonally elongated octahedral sites (e.g., octahedral interstitial sites), as supported by the extensive EPR studies for Cu 2 + in various tetragonally elongated octahedra (both crystalline [32][33][34][35][36] and amorphous [37][38][39][40][41][42] systems). Therefore, the impurity Cu 2 + may tend to occupy some octahedral sites available (e.g., the octahedral interstitial sites) in the studied systems and thus exhibit the tetragonally elongated [CuO 6 ] 10− units due to the JahnTeller distortions via the vibration interactions [11,16,43].…”

Thermal, IR, Raman characteristics, Raman gain coefficient and bandwidths in quaternary glasses

“…A weak band labeled (E) around at 750e779 cm À1 can be attributed to the stretching mode of [TeO 3 ] trigonal pyramid with nonbridging oxygen. A band labeled (F) at 803e857 cm À1 due to the formation of WO 4 groups has been observed with WeOeW vibration [25]. A band labeled (G) around 905e924 cm À1 assigned to the vibrations of NbO 6 octahedral group [15,20].…”

Theoretical studies of the electron paramagnetic resonance parameters and local structures for Cu2+ in (100-2x)TeO2-xAg2O-xWO3 glasses

“…In the light of the observed g factors (2 < g ⊥ < g [13]) for Cu 2+ in TAW glasses at all concentrations x, the impurities Cu 2+ are expected to locate at suitable octahedral sites, with the octahedral [CuO 6 ] 10− clusters showing the tetragonal elongation distortions due to the Jahn-Teller effect [14][15][16][17][18]. For a tetragonally elongated 3d 9 cluster, the original lower two-fold orbitally degenerated irreducible representation 2E g of cubic symmetry may be separated into two orbital singlets 2 B 1g and 2 A 1g , the former being the new ground state.…”

“…As a popular dopant in oxide glasses, Cu 2+ is widely used to probe the local structural properties due to the prominent EPR signals recordable at room temperature. Recently, d-d transition optical absorption and EPR experiments were performed for (100-2x)TeO 2−x Ag 2 O −x WO 3 (7.5 ≤ x ≤ 30 mol %) glasses with 1 mol % CuO dopants [13]. The measured EPR parameters (g factors g and g ⊥ and hyperfine structure constants A ) were analyzed for the various WO 3 or Ag 2 O concentrations by using the simple g formulas and some adjustable bonding parameters α 2 , β 2 1 , and β 2 (which are largely higher than unity) [13].…”

“…Recently, d-d transition optical absorption and EPR experiments were performed for (100-2x)TeO 2−x Ag 2 O −x WO 3 (7.5 ≤ x ≤ 30 mol %) glasses with 1 mol % CuO dopants [13]. The measured EPR parameters (g factors g and g ⊥ and hyperfine structure constants A ) were analyzed for the various WO 3 or Ag 2 O concentrations by using the simple g formulas and some adjustable bonding parameters α 2 , β 2 1 , and β 2 (which are largely higher than unity) [13]. However, the defect structure around impurity Cu 2+ in TAW glasses and its concentration dependence has not been theoretically obtained up to now.…”