Local structure and conductivity of highly conductive vanadate glasses containing different metal oxides

• Published in: Journal of materials science. Materials in electronics Vol. 31; no. 24; pp. 22881 - 22892
• Main Authors: Nishida, Tetsuaki, Oka, Nobuto, Sakuragi, Takahisa, Matsusako, Shunsuke, Imamura, Ryota, Sato, Yasushi
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.12.2020; Springer Nature B.V
• Subjects: Aluminum oxide; Annealing; Carrier density; Characterization and Evaluation of Materials; Chemistry and Materials Science; Conduction bands; Conductivity; Copper oxides; Gallium oxides; Germanium oxides; Glass; Heat treatment; Manganese dioxide; Materials Science; Metal oxides; Molybdenum oxides; Molybdenum trioxide; N-type semiconductors; Optical and Electronic Materials; Reflectance; Room temperature; Tin dioxide; Vanadates; Zinc oxide
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-020-04815-4

Heat treatment of 20BaO· x M m O n ·(10− x )Fe 2 O 3 ·70V 2 O 5 glasses containing different metal oxides (M m O n ), such as Fe 2 O 3 , Al 2 O 3 , MnO 2 , CuO, Cu 2 O, ZnO, Ga 2 O 3 , GeO 2 , MoO 3 , SnO 2 and WO 3 , was accompanied by a remarkable decrease in DC -resistivity ( ρ ) at room temperature from the order of MΩ cm to Ω cm. N -type semiconductor model could be successfully applied to discuss the conduction mechanism. Introduction of CuO into network former (NWF) sites caused a remarkable change of ρ from 2.6 × 10 5 to 3.1 Ω cm when annealed at 450 °C for 30 min. Activation energy for conduction ( E a ) decreased from 0.16 to 0.10 eV, suggesting an increased carrier density in the conduction band. Diffuse reflectance spectra of this glass showed a decrease in the bandgap energy ( E g ) from 2.41 to 2.14 eV. Introduction of ZnO into network modifier (NWM) sites resulted in a remarkable decrease in ρ from 4.0 × 10 5 to 4.8 Ω cm after annealing at 450 °C for 30 min, together with a decrease in E a from 0.23 to 0.14 eV. Diffuse reflectance spectra showed a decrease in E g from 2.39 to 2.11 eV. These results prove that heat treatment of vanadate glass causes structural relaxation and concordant decrease in E a and E g which are responsible for the remarkable increase in the high conductivity.