Structural, Optical and Dielectric Properties of Aluminoborosilicate Glasses

Doping impacts of La2O3 on physical, structural, optical and radiation shielding properties of (30-x)BaCO3–30TiO2–40SiO2-xLa2O3 (0 ≤ x ≤ 6) glasses for optoelectronic applications

“…The obtained values indicated the more structure defects on increasing the concentration of La 2 O 3. Davis and Mott suggested that the E u values lie between 0.045-0.66 eV for amorphous (semiconducting) materials [47]. Hence, in the present studied glasses the defects (disorder) increased due the incorporation of modifiers as well as former La 2 O 3 inside the glass system.…”

“…The Molar Refractivity (R m ) of the prepared glasses depends on V m and optical energy gap (E g ind ), evaluated by the following mentioned relation [43,47];…”

“…Where, N A (= 6.02214076 × 10 23 ) denotes Avogadro's number. However, the reflection loss (R L ) can be determined by the following relation [43,47]:…”

“…From figure 6(c) it is clear that as we increase the amount of La 2 O 3, the values of E g ind were decreased in this manner 3.920, 3.850, 3.810, and 3.770 for BTS0L, BTS2L, BTS4L, and BTS6L respectively. The possible reason for reduction of E g ind might be the enhancement of NBOs inside the glasses due to the increasing concentration of La 2 O 3 and also due to the decrease in the delocalization of e − s, donor centre increased which results in the lower energy gap [36,47,71] . The ionisation of oxygen atoms increases due to the conversion of BOs to NBOs which reduces the separation between valence band (VB) and conduction band (CB) by raising the top of VB towards CB [47,71].…”

“…The possible reason for reduction of E g ind might be the enhancement of NBOs inside the glasses due to the increasing concentration of La 2 O 3 and also due to the decrease in the delocalization of e − s, donor centre increased which results in the lower energy gap [36,47,71] . The ionisation of oxygen atoms increases due to the conversion of BOs to NBOs which reduces the separation between valence band (VB) and conduction band (CB) by raising the top of VB towards CB [47,71]. Moreover, a graph was plotted ln α versus hυ, well known as Urbach plot (figure 7(a)) and by taking the reciprocal slope of the tangent of each plotted curve (accordingly equation (11)), the values of E u (eV) were determined and found in increased order 0.304, 0.329, 0.349, and 0.359 respectively.…”