Thermal, optical and electrical properties of MnO2-doped mixed sodium potassium phosphate glasses

• Published in: Journal of thermal analysis and calorimetry Vol. 146; no. 3; pp. 1077 - 1090
• Main Authors: Jerroudi, M., Bih, L., Yousfi, S., Bejjit, L., Haddad, M., Manoun, B., Lazor, P.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2021; Springer Nature B.V
• Subjects: Absorption spectra; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Conductivity; Crystallization; Density; Differential thermal analysis; Electrical properties; Electron paramagnetic resonance; Energy gap; Glass transition temperature; Glasses; Heat treatment; Inorganic Chemistry; Manganese dioxide; Manganese ions; Measurement Science and Instrumentation; Molar volume; Optical; Optical properties; Parameters; Phase transitions; Phosphate; Physical Chemistry; Polymer Sciences; Potassium phosphates; Structure; Temperature; Vibration mode; Vitreous materials; Glasses; Conductivity; Structure; Phosphate; Optical; Crystallization
• ISSN: 1388-6150; 1588-2926; 1588-2926
• DOI: 10.1007/s10973-020-10133-y

Glasses in the system (1 −  x )(0.5NaPO 3 –0.5KPO 3 )– x MnO 2 , with 0 ≤  x  ≤ 50 mol%, have been prepared using a melt-quench route. The glasses exhibit a yellow to dark color with the increase in manganese content owing to the presence of Mn 2+ and Mn 3+ ions in the network. The amorphous state of the glasses is evidenced by the X-ray diffraction. In order to get an insight into the physical and structural aspects of these vitreous materials, we have determined some of their parameters such as density, molar volume and glass transition temperature. From differential thermal analysis scan on heating, we evaluated the glass transition temperature ( T g ) of each glass, which corresponds to the phase transition temperature from solid to viscous liquid. The density ( ρ ) as a structural index is found to increase while the corresponding molar volume decreases with MnO 2 content. The structural approach of the studied glasses is evaluated by infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies. IR technique allowed us to identify the coexisting bond vibration modes in the glass network, and it has shown that many structural phosphates units coexist, mainly pyrophosphate and metaphosphate structural groups. EPR experiments have shown the presence of Mn 2+ centers in the glasses. The UV–Visible absorption is utilized to estimate the values of the optical band gap ( E g ) and Urbach energy (Δ E ). The optical band gap energy is determined from both the absorption spectrum fitting (ASF) and Tauc’s methods. These optical parameters are composition dependence. The dc conductivity of the glasses is determined in the temperature range from 303 to 473 K. It decreases with increasing manganese content. It is thermally activated and followed an Arrhenius behavior. The crystallization of glasses is realized by submitting them to heat treatments, and the crystallized phases are identified by XRD analysis. The crystallization kinetic was studied under non-isothermal conditions. The activation energy ( E c ) and the Avrami parameter ( n ) were determined.