Thermal stability and transport studies of (100−2x)TeO2–xAg2O–xWO3 (7.5≤x≤30) glass system

Abstract

Typical modulated DSC (NRHF and C p ) results during a heating scan in the 85TeO 2 –7.5Ag 2 O–7.5WO 3 glass sample. ▶ The addition of equal mol% of WO 3 and Ag 2 O to TeO 2 increases the thermal stability. ▶ The 55TeO 2 –22.5WO 3 –22.5Ag 2 O shows the highest thermal stability (Δ T = 237 °C). ▶ These glasses are more useful for drawing of optical fibers. ▶ The present glass system shows higher conductivity . Differential scanning calorimetry (DSC), infrared (IR) and direct current (DC) conductivity studies have been carried out on (100 − 2 x )TeO 2 – x Ag 2 O– x WO 3 (7.5 ≤ x ≤ 30) glass system. The IR studies show that the structure of glass network consists of [TeO 4 ], [TeO 3 ]/[TeO 3+1 ], [WO 4 ] units. Thermal properties such as the glass transition ( T g ), onset crystallization ( T o ), thermal stability (Δ T ), glass transition width (Δ T g ), heat capacities in the glassy and liquid state ( C pg and C pl ), heat capacity change (Δ C p ) and ratios C pl / C pg of the glass systems were calculated. The highest thermal stability (237 °C) obtained in 55TeO 2 –22.5Ag 2 O–22.5WO 3 glass suggests that this new glass may be a potentially useful candidate material host for rare earth doped optical fibers. The DC conductivity of glasses was measured in temperature region 27–260 °C, the activation energy ( E act ) values varied from 1.393 to 0.272 eV and for the temperature interval 170–260 °C, the values of conductivity ( σ ) of glasses varied from 8.79 × 10 −9 to 1.47 × 10 −6 S cm −1 .