EPR AND DSC STUDIES ON MgO–R₂O–B₂O₃–V₂O₅ ALKALI GLASSES

Abstract

EPR and DSC studies were carried out on MgO – R 2 O – B 2 O 3 – V 2 O 5 glasses. The electron paramagnetic resonance spectra of V 4+ ion in the ternary glass system x MgO –(30-x) R 2 O –70 B 2 O 3 ( R = Li, Na, K ) were recorded at X-band frequencies at 303 K. The V 4+ ions in the present glass system exists as VO 2+ ions in octahedral coordination with tetragonal compression. The site symmetry of vanadyl is C 4v and the ground state of 3d 1 ion is d xy . Tetragonality (Δg ‖ /Δg ⊥ ) of V 4+ ion sites show a nonlinear variation with MgO content in the glasses. The covalency rates indicate moderate covalency for σ and π-bonds. The optical basicity values were also reported. Glass transition temperatures (T g ) of the glasses were found to increase linearly with increasing MgO content.