Spectroscopic investigation of new manganese tellurite glasses synthesized by sol-gel method

New tellurite glasses of the xMnO(100-x)TeO2 system with x = 0–26.2 mol % were prepared by sol-gel method. X-ray diffraction and FTIR, UV–Vis, electron paramagnetic resonance (EPR) and photoluminescence (PL) spectroscopies were used to investigate the structural and behavioural properties of the samples. X-ray analysis confirms the amorphous nature of samples. FTIR spectra reveal the presence of TeO3, TeO4 and TeO6 vibrational modes. Addition of manganese ions to the samples produces the change of tellurium ions coordination, namely the conversion of TeO4 into TeO3 structural units up to x = 12.4 mol% MnO. UV-VIS spectroscopy data show the presence of Te=O bonds from [TeO3] structural units and of transitions characteristic of Mn2+ and Mn3+ ions. The EPR spectra of the xMnO(100-x)TeO2 glasses are due to the presence of Mn2+ ions and consist of two resonance absorptions, a weak one located at geff ≈ 4.3 and a strong one at geff ≈ 2.0. The nature of EPR absorption lines and the influence of manganese content on the evolution of EPR lines intensity and linewidth are discussed. The PL spectra are due to the presence of manganese and tellurium ions in the studied samples.