EPR and optical investigations of manganese ions in alkali lead tetraborate glasses

Spectroscopic and dielectric studies on MnO doped PbO–Nb2O5–P2O5 glass system

“…By diagonalising the energy matrices for d 5 configuration, the clearly resolved band observed at 520 nm in the optical absorption spectra of PbO-Nb 2 O 5 -P 2 O 5 :MnO glasses (containing MnO up to 1.0 mol%) is assigned to 6 A 1g (S) → 4 T 1g (G) transitions and the crystal field parameter D q and Racah interelectronic repulsion parameter B have been determined as 695 and 780 cm −1 , respectively. The values of the D q and B obtained are consistent with the values reported in the literature for number of other glass systems [37,[50][51][52]. From these values, it may be concluded that in this concentration range divalent manganese ions occupy octahedral positions.…”

“…Further the growth of the band at about 420 nm at the cost of band at the 520 nm suggests the transformation of Mn 2+ (d 5 ) ions from octahedral to tetrahedral environment with increase in the concentrations of MnO up to 1.0 mol%. The appearance of a broad band in the spectra of the glasses containing MnO beyond 1.0 mol%, at about 490 nm (due to spin allowed 5 E g → 5 T 2g transition) indicates that a part of manganese ions exist in Mn 3+ (d 4 ) and occupy octahedral positions [5,49,52]. Normally, the octahedrally positioned ions (if they do not go in to substitutional positions) act as modifiers.…”

EPR and Optical Spectroscopy of Iron Doped Mixed Alkali Cadmium Phosphate Glasses

“…Table II. In the present LiNaCdP glasses, because of the ionic radii of iron ions [37], there is no such higher variation in g values with concentration variation of alkali content. From Table II it is also observed that when the lithium concentration increases the ironligand bonding covalency nature decreases to some extent.…”

Absorption Studies on Some Silicate and Cabal Glasses Containing NiO or Fe2O3or Mixed NiOi + Fe2O3

“…Although studies on iron in glass have attracted the attention of the majority of scientists interested in transition metal behavior in various glasses, yet much recent work by Sreekanth Chakradhar et al [16,17] have postulated that Fe 3+ ions exhibit an octahedral symmetry in contradiction with most previous published works. It is (471) evident, therefore, that further studies are still needed by different recent techniques to justify the exact coordination of both iron states in various glasses.…”

“…The majority of Fe ions are believed by many authors to occupy tetrahedral network-forming sites in silicate glasses [10,11,14], although this has been disputed. Conversely, the majority of Fe 2+ ions are thought to occupy octahedral network--modifying sites [15][16][17].…”