Infrared and Raman spectroscopic studies of Mn 2+ ions doped in strontium alumino borate glasses: Describes the role of Al 2 O 3 .

Strontium alumino borate glasses doped with Mn2+ ions (SABM) have been prepared and characterized by XRD, density, Electron paramagnetic resonance (EPR), FT-IR and Raman to investigate the spectral and physical properties of the present glass samples. The FTIR spectra revealed the presence of BO3 and BO4 structural units in SABM glasses. The IR peak at ~467 and ~679 cm-1 assigned as the vibration of metal cations (Sr2+ ), MnO bond vibrations and bending vibration of AlO in [AlO4 ] units. The Raman band ~786 cm-1 establishes the presence of AlO4 units. It has been found that an increasing the Al2 O3 content increases the bond length of the AlO bond in AlO4 which leads to increase molar volume and decrease density. Differential scanning calorimetry (DSC) studies indicated that the glass transition temperature (Tg ) decreases with increase of Al2 O3 . Evaluated g and A values from EPR spectra gave the conformation about the ionic bonding between the Mn2+ and its neighbouring oxygen ions.