Enhancing the electrical conduction in sodium borosilicate titanate glass doped with Nd or Gd ions to increase its optical absorption for smart windows applications

Abstract

There are many glass systems that have applications due to their advantages like high optical absorption, high ionic and electronic conductivities. In this work two groups of borosilicate titanate glass doped with one of rare earth oxides with composition in mol% 40 Na2B4O7-40 SiO2-(20–x) TiO2-x M2O3, where M is (Nd or Gd) and x=(0, 0.5, 1 or 1.5) were prepared by melt quenching technique at 1373 K. The prepared glasses were characterized using XRD, FTIR, UV- Vis spectroscopy and dc, ac conductivities. The dc electrical conductivity was investigated for all glass samples in the temperature range (298–523) K. The ac electrical conductivity was measured in the frequency range (50 Hz to 2 MHz) and temperature range (298–523) K. The XRD results confirmed the amorphous nature of the studied glasses. UV–vis measurements revealed that the titanium ions exist in two valance states. The FTIR analysis revealed the presence of non-bridging oxygen, trigonal and tetrahedral borate groups. The highest electrical conductivity reached 3.54 × 10−3 S cm−1. The electron hopping due to the presence of two titanium valances is responsible for electronic conduction while the presence of sodium ions, tetrahedral borate groups and non-bridging oxygen are responsible for ionic conduction, the samples that have optical absorption and the highest conductivity at relatively low temperature close to the room temperature are the samples (H and K) which are promising for smart windows application.